阅读说明：本技术 具有氮化硼镓三元合金层和第二iii族氮化物三元合金层的异质结的半导体器件 (Semiconductor device having a heterojunction with a boron-gallium-nitride ternary alloy layer and a second group-III-nitride ternary alloy layer ) 是由 李晓航 刘开锴 于 2018-10-10 设计创作，主要内容包括：提供了一种用于形成半导体器件的方法,所述半导体器件具有布置在第二III族氮化物三元合金层上的第一III族氮化物三元合金层的异质结。确定用于第一III族氮化物三元合金层和第二III族氮化物三元合金层的III族氮化物元素的浓度范围,使得在第一III族氮化物三元合金层和第二III族氮化物三元合金层的异质结的界面处的极化强度差的绝对值小于或等于0.007C/m<Sup>2</Sup>或大于或等于0.04C/m<Sup>2</Sup>。从确定的浓度范围中选择用于第一III族氮化物三元合金层和第二III族氮化物三元合金层的III族氮化物元素的特定浓度,使得在第一III族氮化物三元合金层和第二III族氮化物三元合金层的异质结的界面处的极化强度差的绝对值小于或等于0.007C/m<Sup>2</Sup>或大于或等于0.04C/m<Sup>2</Sup>。利用所选择的用于第一III族氮化物三元合金层和第二III族氮化物三元合金层的III族氮化物元素的特定浓度来形成半导体器件。第一III族氮化物三元合金层和第二III族氮化物三元合金层具有纤锌矿晶体结构。第一III族氮化物三元合金层是BGaN,并且第二III族氮化物三元合金层是InGaN、InAlN、BAlN或AlGaN。(A method is provided for forming a semiconductor device having a heterojunction with a first group III nitride ternary alloy layer disposed on a second group III nitride ternary alloy layer. Determining concentration ranges of group III nitride elements for the first and second group III nitride ternary alloy layers such that an absolute value of a difference in polarization intensity at an interface of a heterojunction of the first and second group III nitride ternary alloy layers is less than or equal to 0.007C/m 2 Or greater than or equal to 0.04C/m 2 . The specific concentrations of the group III nitride elements for the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer are selected from a determined concentration range such that the absolute value of the difference in polarization strength at the interface of the heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer is less than or equal to 0.007C/m 2 Or greater than or equal to 0.04C/m 2 . A semiconductor device is formed with a particular concentration of group III nitride element selected for the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer. The first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer have a wurtzite crystal structure. The first group III nitride ternary alloy layer is BGaN and the second group III nitride ternary alloy layer is InGaN, InAlN, BAlN, or AlGaN.)

1. A method for forming a semiconductor device (200, 400) comprising a heterojunction of a first group III nitride ternary alloy layer (205, 405) disposed on a second group III nitride ternary alloy layer (210, 410), the method comprising:

determining (105) that an absolute value of a difference in polarization strength at an interface (207, 407) of a heterojunction of the first group III nitride ternary alloy layer (205, 405) and the second group III nitride ternary alloy layer (210, 410) should be less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m²；

Determining (110) a concentration range of group III nitride elements of the first group III nitride ternary alloy layer (205, 405) and the second group III nitride ternary alloy layer (210, 410) such that an absolute value of a difference in polarization strength at an interface (207, 407) of a heterojunction of the first group III nitride ternary alloy layer (205, 405) and the second group III nitride ternary alloy layer (210, 410) is less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m²；

Selecting (115) a specific concentration of group III nitride elements of the first group III nitride ternary alloy layer (205, 405) and the second group III nitride ternary alloy layer (210, 410) from the determined concentration range such that an absolute value of a difference in polarization intensity at an interface (207, 407) of a heterojunction of the first group III nitride ternary alloy layer (205, 405) and the second group III nitride ternary alloy layer (210, 410) is less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m²(ii) a And

forming (120) the semiconductor device (200, 400) including a heterojunction with a particular concentration of group III nitride elements of the first group III nitride ternary alloy layer (205, 405) and the second group III nitride ternary alloy layer (210, 410) selected,

wherein the first group III-nitride ternary alloy layer (205, 405) and the second group III-nitride ternary alloy layer (210, 410) have a wurtzite crystal structure, and

wherein the first group III-nitride ternary alloy layer (205, 405) is boron gallium nitride, BGaN; and the second group III-nitride ternary alloy layer (205, 405) is indium gallium nitride (InGaN), indium aluminum nitride (InAIN), boron aluminum nitride (BAlN), or aluminum gallium nitride (AlGaN).

2. The method of claim 1, further comprising:

determining concentration ranges of group III nitride elements of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer based on a sum of a spontaneous polarization and a piezoelectric polarization of the first group III nitride ternary alloy layer, and based on a sum of a spontaneous polarization and a piezoelectric polarization of the second group III nitride ternary alloy layer.

3. The method of claim 2, wherein

The first group III nitride ternary alloy layer includes B_xGa_1-xN，

The second group III nitride ternary alloy layer includes In_yGa_1-yN，

The spontaneous polarization strength of the first III-nitride ternary alloy layer is C/m²Is a unit, and it is equal to 0.4383x²+0.3135x +1.3544, and

the spontaneous polarization strength of the second III-nitride ternary alloy layer is C/m²Is a unit, and it is equal to 0.1142y²-0.2892y+1.3424。

4. The method of claim 3, wherein

The first group III nitride ternary alloy layer has a piezoelectric polarization of

The second group III nitride ternary alloy layer has a piezoelectric polarization of

e₃₁(x) Is a layer of said first group III nitride ternary alloyInternal strain term of piezoelectric constant in C/m²And it is equal to 0.9809x²-0.4007x-0.3104，

e₃₃(x) A clamping ion term of the piezoelectric constant of the first III-nitride ternary alloy layer with the unit of C/m²And it is equal to-2.1887 x²+0.8174x+0.5393，

e₃₁(y) is an internal strain term of the piezoelectric constant of the second group III nitride ternary alloy layer, in units of C/m²And it is equal to 0.2396y²-0.4483y-0.3399，

e₃₃(y) a clamping ion term of the piezoelectric constant of the second group III nitride in the unit of C/m²And it is equal to-0.1402 y²+0.5902y+0.6080，

α (x) andis a unit and is the lattice constant of the first group III nitride ternary alloy layer,

α (y) andis a unit and is the lattice constant of the second aluminum nitride ternary alloy layer,

α_relax(x) To be provided withIs a unit and is the complete relaxed lattice constant of the first group III nitride ternary alloy layer,

α_relax(y) is prepared byIs a unit and is the complete relaxed lattice constant of the second group III nitride ternary alloy layer,

C₁₃(x) And C₃₃(x) In GPa and is the elastic constant of the first group III nitride ternary alloy layer,

C₁₃(y) and C₃₃(y)In GPa and is the elastic constant of the second group III nitride ternary alloy layer,

P_SP(x) Is the spontaneous polarization of the first group III nitride ternary alloy layer, an

P_SP(y) is the spontaneous polarization of the second group III nitride ternary alloy layer.

5. The method of claim 2, wherein

The first group III nitride ternary alloy layer includes B_xGa_1-xN，

The second group III nitride ternary alloy layer includes In_yAl_1-yN，

The spontaneous polarization strength of the first III-nitride ternary alloy layer is C/m²Is a unit, and it is equal to 0.4383x²+0.3135x +1.3544, and

the spontaneous polarization strength of the second III-nitride ternary alloy layer is C/m²Is in units, and it equals 0.1563y²-0.3323y+1.3402。

6. The method of claim 5, wherein

The first group III nitride ternary alloy layer has a piezoelectric polarization of

The second group III nitride ternary alloy layer has a piezoelectric polarization of

e₃₁(x) Is an internal strain term of the piezoelectric constant of the first group III nitride ternary alloy layer, and has a unit of C/m²And it is equal to 0.9809x²-0.4007x-0.3104，

e₃₃(x) Is a layer of said first group III nitride ternary alloyClamping ion term of piezoelectric constant in C/m²And it is equal to-2.1887 x²+0.8174x+0.5393，

e₃₁(y) is an internal strain term of the piezoelectric constant of the second group III nitride ternary alloy layer, in units of C/m²And it is equal to-0.0959 y²+0.239y-0.6699，

e₃₃(y) a clamping ion term of the piezoelectric constant of the second group III nitride in the unit of C/m²And it is equal to 0.9329y²-1.5036y+1.6443，

α (x) andis a unit and is the lattice constant of the first group III nitride ternary alloy layer,

α (y) andis a unit and is the lattice constant of the second aluminum nitride ternary alloy layer,

α_relax(x) To be provided withIs a unit and is the complete relaxed lattice constant of the first group III nitride ternary alloy layer,

α_relax(y) is prepared byIs a unit and is the complete relaxed lattice constant of the second group III nitride ternary alloy layer,

C₁₃(x) And C₃₃(x) In GPa and is the elastic constant of the first group III nitride ternary alloy layer,

C₁₃(y) and C₃₃(y) is in GPa and is the elastic constant of the second group III-nitride ternary alloy layer,

P_SP(x) Is the spontaneous polarization of the first group III nitride ternary alloy layer,and

P_SP(y) is the spontaneous polarization of the second group III nitride ternary alloy layer.

7. The method of claim 2, wherein

The first group III nitride ternary alloy layer includes B_xGa_1-xN，

The second group III nitride ternary alloy layer includes B_yAl_1-yN，

The spontaneous polarization strength of the first III-nitride ternary alloy layer is C/m²Is a unit, and it is equal to 0.4383x²+0.3135x +1.3544, and

the spontaneous polarization strength of the second III-nitride ternary alloy layer is C/m²Is in units, and it equals 0.6287y²+0.1217y+1.3542。

8. The method of claim 7, wherein

The first group III nitride ternary alloy layer has a piezoelectric polarization of

The second group III nitride ternary alloy layer has a piezoelectric polarization of

e₃₁(x) Is an internal strain term of the piezoelectric constant of the first group III nitride ternary alloy layer, and has a unit of C/m²And it is equal to 0.9809x²-0.4007x-0.3104，

e₃₃(x) A clamping ion term of the piezoelectric constant of the first III-nitride ternary alloy layer with the unit of C/m²And it is equal to-2.1887 x²+0.8174x+0.5393，

e₃₁(y) is the second group III nitride triadInternal strain term of piezoelectric constant of gold layer with unit of C/m²And it is equal to 1.7616y²-0.9003y-0.6016，

e₃₃(y) a clamping ion term of the piezoelectric constant of the second group III nitride in the unit of C/m²And it is equal to-4.0355 y²+1.6836y+1.5471，

α (x) andis a unit and is the lattice constant of the first group III nitride ternary alloy layer,

α (y) andis a unit and is the lattice constant of the second aluminum nitride ternary alloy layer,

α_relax(x) To be provided withIs a unit and is the complete relaxed lattice constant of the first group III nitride ternary alloy layer,

α_relax(y) is prepared byIs a unit and is the complete relaxed lattice constant of the second group III nitride ternary alloy layer,

C₁₃(x) And C₃₃(x) In GPa and is the elastic constant of the first group III nitride ternary alloy layer,

C₁₃(y) and C₃₃(y) is in GPa and is the elastic constant of the second group III-nitride ternary alloy layer,

P_SP(x) Is the spontaneous polarization of the first group III nitride ternary alloy layer, an

P_SP(y) is the spontaneous polarization of the second group III nitride ternary alloy layer.

9. The method of claim 2, wherein

The first group III nitride ternary alloy layer includes B_xGa_1-xN，

The second group III nitride ternary alloy layer includes Al_yGa_1-yN，

The spontaneous polarization strength of the first III-nitride ternary alloy layer is C/m²Is a unit, and it is equal to 0.4383x²+0.3135x +1.3544, and

the spontaneous polarization strength of the second III-nitride ternary alloy layer is C/m²Is a unit, and it is equal to 0.0072x²-0.0127x+1.3389。

10. The method of claim 9, wherein

The first group III nitride ternary alloy layer has a piezoelectric polarization of

The second group III nitride ternary alloy layer has a piezoelectric polarization of

e₃₁(x) Is an internal strain term of the piezoelectric constant of the first group III nitride ternary alloy layer, and has a unit of C/m²And it is equal to 0.9809x²-0.4007x-0.3104，

e₃₃(x) A clamping ion term of the piezoelectric constant of the first III-nitride ternary alloy layer with the unit of C/m²And it is equal to-2.1887 x²+0.8174x+0.5393，

e₃₁(y) is an internal strain term of the piezoelectric constant of the second group III nitride ternary alloy layer, in units of C/m²And it is equal to-0.0573 y²-0.2536y-0.3582，

e₃₃(y) is the second group III nitrideThe clamping ion term of the piezoelectric constant of (1), in the unit of C/m²And it is equal to 0.3949y²+0.6324y+0.6149，

α (x) andis a unit and is the lattice constant of the first group III nitride ternary alloy layer,

α (y) andis a unit and is the lattice constant of the second aluminum nitride ternary alloy layer,

α_relax(x) To be provided withIs a unit and is the complete relaxed lattice constant of the first group III nitride ternary alloy layer,

α_relax(y) is prepared byIs a unit and is the complete relaxed lattice constant of the second group III nitride ternary alloy layer,

C₁₃(x) And C₃₃(x) In GPa and is the elastic constant of the first group III nitride ternary alloy layer,

C₁₃(y) and C₃₃(y) is in GPa and is the elastic constant of the second group III-nitride ternary alloy layer,

P_SP(x) Is the spontaneous polarization of the first group III nitride ternary alloy layer, an

P_SP(y) is the spontaneous polarization of the second group III nitride ternary alloy layer.

11. A semiconductor device (200, 400) comprising:

a heterojunction comprising a first group III-nitride ternary alloy layer (205, 405) disposed on a second group III-nitride ternary alloy layer (210, 410), wherein

An absolute value of a difference in polarization strength at an interface (207, 407) of a heterojunction of the first group III nitride ternary alloy layer (205, 405) and the second group III nitride ternary alloy layer (210, 410) is less than or equal to 0.007C/m based on a concentration of a group III nitride element of the first group III nitride ternary alloy layer (205, 405) and the second group III nitride ternary alloy layer (210, 410)²Or greater than or equal to 0.04C/m²，

The first group III-nitride ternary alloy layer (205, 405) and the second group III-nitride ternary alloy layer (210, 410) have a wurtzite crystal structure, and

the first group III-nitride ternary alloy layer (205, 405) is boron gallium nitride BGaN; and the second group III-nitride ternary alloy layer (210, 410) is indium gallium nitride (InGaN), indium aluminum nitride (InAIN), boron aluminum nitride (BAlN), or aluminum gallium nitride (AlGaN).

12. The semiconductor device of claim 11, wherein the second group III nitride ternary alloy layer is a substrate of the semiconductor device.

13. The semiconductor device of claim 11, further comprising:

a substrate having the second III-nitride ternary layer disposed thereon.

14. The semiconductor device of claim 11, wherein an absolute value of a difference in polarization intensity at an interface of a heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer is less than or equal to 0.007C/m²And the semiconductor device is an optoelectronic device.

15. The semiconductor device of claim 11, wherein an absolute value of a difference in polarization strength at an interface of a heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer is greater than or equal to 0.04C ÷ orm²And the semiconductor device is a high electron mobility transistor, HEMT.

16. A method for forming a semiconductor device (400) on a substrate (415), the semiconductor device comprising a heterojunction of a first group III nitride ternary alloy layer (405) disposed on a second group III nitride ternary alloy layer (410), the method comprising:

determining (305) that an absolute value of a difference in polarization strength at an interface (407) of a heterojunction of the first group III nitride ternary alloy layer (405) and the second group III nitride ternary alloy layer (410) should be less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m²；

Determining (310) a concentration range of group III nitride elements of the first group III nitride ternary alloy layer (405) and the second group III nitride ternary alloy layer (410) and determining a lattice constant of the substrate (415) such that an absolute value of a difference in polarization strength at an interface (407) of a heterojunction of the first group III nitride ternary alloy layer (405) and the second group III nitride ternary alloy layer (410) is less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m²；

Selecting (315) a specific concentration of a group III nitride element of the first group III nitride ternary alloy layer (405) and the second group III nitride ternary alloy layer (410) and a specific substrate from the determined concentration range such that an absolute value of a difference in polarization strength at an interface (407) of a heterojunction of the first group III nitride ternary alloy layer (405) and the second group III nitride ternary alloy layer (410) is less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m²(ii) a And

forming (320) the semiconductor device comprising a heterojunction on a substrate (415) with a particular concentration of group III nitride elements of the first group III-nitride ternary alloy layer (405) and the second group III-nitride ternary alloy layer (410) selected and a particular substrate,

wherein the first group III-nitride ternary alloy layer (405) and the second group III-nitride ternary alloy layer (410) have a wurtzite crystal structure, an

Wherein the first group III-nitride ternary alloy layer (405) is boron gallium nitride (BGaN); and the second group III-nitride ternary alloy layer (410) is indium gallium nitride (InGaN), indium aluminum nitride (InAIN), boron aluminum nitride (BAlN), or aluminum gallium nitride (AlGaN).

17. The method of claim 16, further comprising:

determining a concentration range of a group III nitride element of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer based on a sum of a spontaneous polarization and a piezoelectric polarization of the first group III nitride ternary alloy layer, and based on a sum of a spontaneous polarization and a piezoelectric polarization of the second group III nitride ternary alloy layer, wherein

The first group III nitride ternary alloy layer includes B_xGa_1-xN，

The second group III nitride ternary alloy layer includes In_yGa_1-yN，

The spontaneous polarization strength of the first III-nitride ternary alloy layer is C/m²Is a unit, and it is equal to 0.4383x²+0.3135x+1.3544，

The spontaneous polarization strength of the second III-nitride ternary alloy layer is C/m²Is a unit, and it is equal to 0.1142y²-0.2892y+1.3424，

The first group III nitride ternary alloy layer has a piezoelectric polarization of

The second group III nitride ternary alloy layer has a piezoelectric polarization of

e₃₁(x) Is the first group III nitride ternary complexInternal strain term of piezoelectric constant of gold layer with unit of C/m²And it is equal to 0.9809x²-0.4007x-0.3104，

e₃₃(x) A clamping ion term of the piezoelectric constant of the first III-nitride ternary alloy layer with the unit of C/m²And it is equal to-2.1887 x²+0.8174x+0.5393，

e₃₁(y) is an internal strain term of the piezoelectric constant of the second group III nitride ternary alloy layer, in units of C/m²And it is equal to 0.2396y²-0.4483y-0.3399，

e₃₃(y) a clamping ion term of the piezoelectric constant of the second group III nitride in the unit of C/m²And it is equal to-0.1402 y²+0.5902y+0.6080，

α (x) andis a unit and is the lattice constant of the first group III nitride ternary alloy layer,

α (y) andis a unit and is the lattice constant of the second aluminum nitride ternary alloy layer,

α_relax(x) To be provided withIs a unit and is the complete relaxed lattice constant of the first group III nitride ternary alloy layer,

α_relax(y) is prepared byIs a unit and is the complete relaxed lattice constant of the second group III nitride ternary alloy layer,

C₁₃(x) And C₃₃(x) In GPa and is the elastic constant of the first group III nitride ternary alloy layer,

C₁₃(y) and C₃₃(y) is in GPa and is the elastic constant of the second group III-nitride ternary alloy layer,

P_SP(x) Is the spontaneous polarization of the first group III nitride ternary alloy layer, an

P_SP(y) is the spontaneous polarization of the second group III nitride ternary alloy layer.

18. The method of claim 16, further comprising:

determining a concentration range of a group III nitride element of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer based on a sum of a spontaneous polarization and a piezoelectric polarization of the first group III nitride ternary alloy layer, and based on a sum of a spontaneous polarization and a piezoelectric polarization of the second group III nitride ternary alloy layer, wherein

The first group III nitride ternary alloy layer includes B_xGa_1-xN，

The second group III nitride ternary alloy layer includes In_yAl_1-yN，

The spontaneous polarization strength of the first III-nitride ternary alloy layer is C/m²Is a unit, and it is equal to 0.4383x²+0.3135x+1.3544，

The spontaneous polarization strength of the second III-nitride ternary alloy layer is C/m²Is in units, and it equals 0.1563y²-0.3323y+1.3402，

The first group III nitride ternary alloy layer has a piezoelectric polarization of

The second group III nitride ternary alloy layer has a piezoelectric polarization of

e₃₁(x) Is an internal strain term of the piezoelectric constant of the first group III nitride ternary alloy layer, and has a unit of C/m²And it is equal to 0.9809x²-0.4007x-0.3104，

e₃₃(x) A clamping ion term of the piezoelectric constant of the first III-nitride ternary alloy layer with the unit of C/m²And it is equal to-2.1887 x²+0.8174x+0.5393，

e₃₁(y) is an internal strain term of the piezoelectric constant of the second group III nitride ternary alloy layer, in units of C/m²And it is equal to-0.0959 y²+0.239y-0.6699，

e₃₃(y) a clamping ion term of the piezoelectric constant of the second group III nitride in the unit of C/m²And it is equal to 0.9329y²-1.5036y+1.6443，

α (x) andis a unit and is the lattice constant of the first group III nitride ternary alloy layer,

α (y) andis a unit and is the lattice constant of the second aluminum nitride ternary alloy layer,

α_relax(x) To be provided withIs a unit and is the complete relaxed lattice constant of the first group III nitride ternary alloy layer,

α_relax(y) is prepared byIs a unit and is the complete relaxed lattice constant of the second group III nitride ternary alloy layer,

C₁₃(x) And C₃₃(x) In GPa and is the elastic constant of the first group III nitride ternary alloy layer,

C₁₃(y) and C₃₃(y) is in GPa and is the elastic constant of the second group III-nitride ternary alloy layer,

P_SP(x) Is the spontaneous polarization of the first group III nitride ternary alloy layer, an

P_SP(y) is the spontaneous polarization of the second group III nitride ternary alloy layer.

19. The method of claim 16, further comprising:

determining a concentration range of a group III nitride element of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer based on a sum of a spontaneous polarization and a piezoelectric polarization of the first group III nitride ternary alloy layer, and based on a sum of a spontaneous polarization and a piezoelectric polarization of the second group III nitride ternary alloy layer, wherein

The first group III nitride ternary alloy layer includes B_xGa_1-xN，

The second group III nitride ternary alloy layer includes B_yAl_1-yN，

The spontaneous polarization strength of the first III-nitride ternary alloy layer is C/m²Is a unit, and it is equal to 0.4383x²+0.3135x+1.3544，

The spontaneous polarization strength of the second III-nitride ternary alloy layer is C/m²Is in units, and it equals 0.6287y²+0.1217y+1.3542,

The first group III nitride ternary alloy layer has a piezoelectric polarization of

The second group III nitride ternary alloy layer has a piezoelectric polarization of

e₃₁(x) Is an internal strain term of the piezoelectric constant of the first group III nitride ternary alloy layer, and has a unit of C/m²And it is equal to 0.9809x²-0.4007x-0.3104，

e₃₃(x) A clamping ion term of the piezoelectric constant of the first III-nitride ternary alloy layer with the unit of C/m²And it is equal to-2.1887 x²+0.8174x+0.5393，

e₃₁(y) is an internal strain term of the piezoelectric constant of the second group III nitride ternary alloy layer, in units of C/m²And it is equal to 1.7616y²-0.9003y-0.6016，

e₃₃(y) a clamping ion term of the piezoelectric constant of the second group III nitride in the unit of C/m²And it is equal to-4.0355 y²+1.6836y+1.5471，

α (x) andis a unit and is the lattice constant of the first group III nitride ternary alloy layer,

α (y) andis a unit and is the lattice constant of the second aluminum nitride ternary alloy layer,

α_relax(x) To be provided withIs a unit and is the complete relaxed lattice constant of the first group III nitride ternary alloy layer,

α_relax(y) is prepared byIs a unit and is the complete relaxed lattice constant of the second group III nitride ternary alloy layer,

C₁₃(x) And C₃₃(x) In units of GPa and is the first IThe elastic constant of the group II nitride ternary alloy layer,

C₁₃(y) and C₃₃(y) is in GPa and is the elastic constant of the second group III-nitride ternary alloy layer,

P_SP(x) Is the spontaneous polarization of the first group III nitride ternary alloy layer, an

P_SP(y) is the spontaneous polarization of the second group III nitride ternary alloy layer.

20. The method of claim 16, further comprising:

determining a concentration range of a group III nitride element of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer based on a sum of a spontaneous polarization and a piezoelectric polarization of the first group III nitride ternary alloy layer, and based on a sum of a spontaneous polarization and a piezoelectric polarization of the second group III nitride ternary alloy layer, wherein

The first group III nitride ternary alloy layer includes B_xGa_1-xN，

The second group III nitride ternary alloy layer includes Al_yGa_1-yN，

The spontaneous polarization strength of the first III-nitride ternary alloy layer is C/m²Is a unit, and it is equal to 0.4383x²+0.3135x+1.3544，

The spontaneous polarization strength of the second III-nitride ternary alloy layer is C/m²Is in units, and it equals 0.0072y²-0.0127y+1.3389,

The first group III nitride ternary alloy layer has a piezoelectric polarization of

The second group III nitride ternary alloy layer has a piezoelectric polarization of

e₃₁(x) Is an internal strain term of the piezoelectric constant of the first group III nitride ternary alloy layer, and has a unit of C/m²And it is equal to 0.9809x²-0.4007x-0.3104，

e₃₃(x) A clamping ion term of the piezoelectric constant of the first III-nitride ternary alloy layer with the unit of C/m²And it is equal to-2.1887 x²+0.8174x+0.5393，

e₃₁(y) is an internal strain term of the piezoelectric constant of the second group III nitride ternary alloy layer, in units of C/m²And it is equal to-0.0573 y²-0.2536y-0.3582，

e₃₃(y) a clamping ion term of the piezoelectric constant of the second group III nitride in the unit of C/m²And it is equal to 0.3949y²+0.6324y+0.6149，

α (x) andis a unit and is the lattice constant of the first group III nitride ternary alloy layer,

α (y) andis a unit and is the lattice constant of the second aluminum nitride ternary alloy layer,

α_relax(x) To be provided withIs a unit and is the complete relaxed lattice constant of the first group III nitride ternary alloy layer,

α_relax(y) is prepared byIs a unit and is the complete relaxed lattice constant of the second group III nitride ternary alloy layer,

C₁₃(x) And C₃₃(x) In GPa and is the elastic constant of the first group III nitride ternary alloy layer,

C₁₃(y) and C₃₃(y) is in GPa and is the elastic constant of the second group III-nitride ternary alloy layer,

P_SP(x) Is the spontaneous polarization of the first group III nitride ternary alloy layer, an

P_SP(y) is the spontaneous polarization of the second group III nitride ternary alloy layer.

Technical Field

Embodiments of the disclosed subject matter generally relate to semiconductor devices having a heterojunction of wurtzite group III nitride ternary alloy, wherein the heterojunction exhibits a difference in polarization strength that is either small or large based on the composition of the elements forming the two wurtzite group III nitride ternary alloy layers forming the heterojunction.

Background

Disclosure of Invention

According to an embodiment, there is a method for forming a semiconductor device including a heterojunction of a first group III nitride ternary alloy layer disposed on a second group III nitride ternary alloy layer. First, it was determined that the absolute value of the difference in polarization strength at the interface of the heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer should be less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m². The concentration ranges of the group III nitride elements of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer are determined such that the absolute value of the difference in polarization intensity at the interface of the heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer is less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m². The specific concentrations of the group III nitride elements of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer are selected from a determined concentration range such that the absolute value of the difference in polarization strength at the interface of the heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer is less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m². A semiconductor device including a heterojunction is formed utilizing the selected particular concentrations of group III nitride elements of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer. The first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer have a wurtzite crystal structure. The first group III nitride ternary alloy layer is boron gallium nitride (BGaN), and the second group III nitride ternary alloy layer is indium gallium nitride (InGaN), indium aluminum nitride (InAlN), boron aluminum nitride (BAlN), or aluminum gallium nitride (AlGaN).

According to another embodiment, there is a semiconductor device comprising a heterojunction including a first group III nitride ternary alloy layer disposed on a second group III nitride ternary alloy layer. An absolute value of a difference in polarization strength at an interface of heterojunctions of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer is less than or equal to 0.007C/m based on concentrations of group III nitride elements of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer²Or greater than or equal to 0.04C/m². The first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer have a wurtzite crystal structure. The first group III nitride ternary alloy layer is boron gallium nitride (BGaN), and the second group III nitride ternary alloy layer is indium gallium nitride (InGaN), indium aluminum nitride (InAlN), boron aluminum nitride (BAlN), or aluminum gallium nitride (AlGaN))。

According to further embodiments, there is a method for forming a semiconductor device on a substrate that includes a heterojunction of a first group III nitride ternary alloy layer disposed on a second group III nitride ternary alloy layer. First, it was determined that the absolute value of the difference in polarization strength at the interface of the heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer should be less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m². Determining a concentration range of group III nitride elements of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer and determining a lattice constant of the substrate such that an absolute value of a difference in polarization strength at an interface of a heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer is less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m². Selecting specific concentrations of group III nitride elements of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer from the determined concentration ranges and selecting a specific substrate such that an absolute value of a difference in polarization intensity at an interface of a heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer is less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m². A semiconductor device including a heterojunction is formed on the substrate using the selected group III nitride element specific concentrations of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer and the specific substrate. The first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer have a wurtzite crystal structure. The first group III nitride ternary alloy layer is boron gallium nitride (BGaN), and the second group III nitride ternary alloy layer is indium gallium nitride (InGaN), indium aluminum nitride (InAlN), aluminum gallium nitride (AlGaN), or boron aluminum nitride (BAlN).

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments and, together with the description, explain these embodiments. In the drawings:

FIG. 1 is a flow diagram of a method of forming a semiconductor device including a heterojunction of two wurtzite group III nitride ternary alloy layers, according to an embodiment;

FIG. 2 is a schematic view of a semiconductor device including a heterojunction of two wurtzite group III nitride ternary alloy layers, according to an embodiment;

FIG. 3 is a flow diagram of a method of forming a semiconductor device comprising a heterojunction of two wurtzite group III nitride ternary alloy layers on a substrate according to an embodiment;

FIG. 4 is a schematic view of a semiconductor device including a heterojunction of two wurtzite group III nitride ternary alloy layers on a substrate according to an embodiment;

FIG. 5A is a graph of calculated lattice constant versus boron composition of wurtzite aluminum gallium nitride (AlGaN) according to an embodiment;

FIG. 5B is a graph of calculated lattice constant versus boron composition of wurtzite indium gallium nitride (InGaN) according to an embodiment;

FIG. 5C is a graph of calculated lattice constant versus aluminum composition of wurtzite aluminum indium nitride (InAlN), in accordance with an embodiment;

FIG. 5D is a graph of calculated lattice constant versus indium composition of wurtzite boron aluminum nitride (BAlN) according to an embodiment; and

fig. 5E is a graph of calculated lattice constant versus indium composition of wurtzite boron gallium nitride (BGaN) according to an embodiment.

Detailed Description

Exemplary embodiments are described below with reference to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Rather, the scope of the invention is defined by the appended claims. For simplicity, the following embodiments are discussed with respect to the terminology and structure of wurtzite group III nitride ternary alloys.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Fig. 1 is a flow diagram of a method for forming a semiconductor device including a heterojunction of a first group III nitride ternary alloy layer disposed on a second group III nitride ternary alloy layer according to an embodiment. First, it was determined that the absolute value of the difference in polarization strength at the interface of the heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer should be less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m²(step 105). The concentration ranges of the group III nitride elements of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer are determined such that the absolute value of the difference in polarization intensity at the interface of the heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer is less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m²(step 110).

The specific concentrations of the group III nitride elements of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer are selected from a determined concentration range such that the absolute value of the difference in polarization strength at the interface of the heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer is less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m²(step 115). Finally, a semiconductor device including a heterojunction is formed utilizing the selected particular concentrations of the group III nitride elements of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer (step 120). The first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer have a wurtzite crystal structure. The first group III nitride ternary alloy layer is boron gallium nitride (BGaN), and the second group III nitride ternary alloy layer is indium gallium nitride (InGaN), indium aluminum nitride (InAlN), boron aluminum nitride (BAlN), or aluminum gallium nitride (AlGaN). The formation of the layers can be performed using any technique including, but not limited to, metal organic chemical vapor deposition, molecular beam epitaxy, and high temperature post deposition annealing。

For certain semiconductor devices, such as optoelectronic devices comprising L ED and a laser diode, the absolute value of the difference in polarization intensity at the interface 207 between the first III-nitride ternary alloy layer 105 and the second III-nitride ternary alloy layer 110 is less than or equal to 0.007C/m²Is advantageous. On the other hand, for certain semiconductor devices such as High Electron Mobility Transistors (HEMTs), the absolute value of the difference in polarization intensity at the interface 207 between the first group III nitride ternary alloy layer 105 and the second group III nitride ternary alloy layer 110 is greater than or equal to 0.04C/m²Is advantageous.

Fig. 2 shows a schematic view of a semiconductor device comprising a heterojunction of two wurtzite group III nitride ternary alloy layers according to the method of fig. 1. As shown, the semiconductor device 200 includes a heterojunction that includes a first III-nitride ternary alloy layer 205 disposed on a second III-nitride ternary alloy layer 210. The absolute value of the difference in polarization strength at the interface 207 of the heterojunction of the first group III nitride ternary alloy layer 205 and the second group III nitride ternary alloy layer 210 is less than or equal to 0.007C/m based on the concentration of the group III nitride element of the first group III nitride ternary alloy layer 205 and the second group III nitride ternary alloy layer 210²Or greater than or equal to 0.04C/m². The first group III nitride ternary alloy layer 205 and the second group III nitride ternary alloy layer 210 have a wurtzite crystal structure. The first group III nitride ternary alloy layer 205 is boron gallium nitride (BGaN). The second group III nitride ternary alloy layer 210 is indium gallium nitride (InGaN), indium aluminum nitride (InAlN), boron aluminum nitride (BAlN), or aluminum gallium nitride (AlGaN).

Fig. 3 is a flow diagram of a method for forming a semiconductor device on a substrate including a heterojunction of a first group III nitride ternary alloy layer disposed on a second group III nitride ternary alloy layer. First, it was determined that the absolute value of the difference in polarization strength at the interface of the heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer should be less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m²(step 305). Then, the first group III nitrogen is determinedConcentration ranges of group III nitride elements of the compound ternary alloy layer and the second group III nitride ternary alloy layer, and lattice constants of the substrate are determined such that an absolute value of a difference in polarization intensity at an interface of a heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer is less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m²(step 310).

Selecting specific concentrations of group III nitride elements of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer from the determined concentration ranges and selecting a specific substrate such that an absolute value of a difference in polarization intensity at an interface of a heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer is less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m²(step 315). A semiconductor device including a heterojunction is then formed on the substrate using the selected specific concentrations of the group III nitride elements of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer and the specific substrate (step 320). The first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer have a wurtzite crystal structure. The first group III nitride ternary alloy layer is boron gallium nitride (BGaN), and the second group III nitride ternary alloy layer is indium gallium nitride (InGaN), indium aluminum nitride (InAlN), boron aluminum nitride (BAlN), or aluminum gallium nitride (AlGaN).

The formation of the layers can be performed using any technique including, but not limited to, metal organic chemical vapor deposition, molecular beam epitaxy, and high temperature post deposition annealing.

Fig. 4 shows a schematic view of a semiconductor device comprising a heterojunction of two wurtzite group III nitride ternary alloy layers on a substrate according to the method of fig. 3. As shown, a heterojunction including a first group III-nitride ternary alloy layer 405 is disposed on a second group III-nitride ternary alloy layer 410. A substrate 415 is disposed below the second group III-nitride ternary alloy layer 410. The first group III nitride ternary alloy layer 405 and the second group III nitride ternary alloy layer 410 are based on the concentration of the group III nitride element and the lattice constant of the substrate 415The absolute value of the difference in polarization strength at the interface 407 of the heterojunction of the gold layer 405 and the second group III nitride ternary alloy layer 410 is less than or equal to 0.007C/m²Or greater than or equal to 0.04C/m². The first group III nitride ternary alloy layer 405 and the second group III nitride ternary alloy layer 410 have a wurtzite crystal structure. The first group III nitride ternary alloy layer 405 is boron gallium nitride (BGaN), and the second group III nitride ternary alloy layer 410 is indium gallium nitride (InGaN), indium aluminum nitride (InAlN), boron aluminum nitride (BAlN), or aluminum gallium nitride (AlGaN).

Substrate 415 can be any type of substrate having a lattice constant such that a concentration of group III nitride element less than or equal to 0.007C/m is achieved when the first group III nitride ternary alloy layer 405 and the second group III nitride ternary alloy layer 410 are combined²Or greater than or equal to 0.04C/m²Of the first group III nitride ternary alloy layer 405 and the second group III nitride ternary alloy layer 410, the absolute value of the difference in polarization strength at the interface 407 of the heterojunction. For example, the substrate 415 can be a silicon substrate, a sapphire substrate, a group III nitride binary substrate. Substrate 415 can also be a group III nitride ternary or quaternary alloy virtual substrate with a relaxed or partially relaxed lattice constant grown on another substrate.

As described above, the composition ranges of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer are based on the difference in polarization at the interface between the two layers. Assuming that the first group III nitride ternary alloy layer has a composition A_xC_{1- x}The N, second group III nitride ternary alloy layer has a composition D_yE_1-yN, and the first group III nitride ternary alloy layer is disposed on top of the second group III nitride ternary alloy layer, the difference in polarization at the interface of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer can be calculated as follows:

ΔP(x，y)＝P(A_xC_1-xN)-P(D_yE_1-yN)＝D (1)

wherein P (A)_xC_1-xN) is the polarization of the first group III nitride ternary alloy layer, and P (D)_yE_1-yN) is the polarization of the second group III nitride ternary alloy layer.

The polarization of each layer is based on the sum of the Spontaneous Polarization (SP) of the layer and the piezoelectric Polarization (PZ) of the layer:

P(A_xC_1-xN)＝P_SP(x)+P_PZ(x) (2)

P(D_yE_1-yN)＝P_SP(y)+P_PZ(y) (3)

where x is the percentage of the composition of element a relative to element C in the group III nitride ternary alloy layer in the upper portion of the heterojunction, and y is the percentage of the composition of element D relative to element E in the group III nitride ternary alloy layer in the lower portion of the heterojunction.

More specifically, the polarization of each layer is:

wherein e is₃₁Is the internal-strain term of the piezoelectric constant, e₃₃Is the clamping ion (clamped-ion) term of the piezoelectric constant (determined using the fixed internal parameter μ), e₃₁(x) And e₃₃(x) Is the piezoelectric constant of the III-nitride ternary alloy layer at the upper part of the heterojunction and has the unit of C/m²，e₃₁(y) and e₃₃(y) is the piezoelectric constant of the group III nitride ternary alloy layer at the lower part of the heterojunction, with the unit of C/m²，C₁₃(x) And C₃₃(x) Is the elastic constant of the III-nitride ternary alloy layer at the upper part of the heterojunction, and the unit is GPa and C₁₃(y) and C₃₃(y) is the elastic constant of the group III nitride ternary alloy layer below the heterojunction, with the unit of GPa, where & -lTtT transition = α "& -gTt α & -lTt/T & -gTt (x) is A_xC_1-xLattice constant of the N layer inα (y) is D_yE_1-yLattice constant of the N layer inAnd α_relax(x) Is A_xC_1-xThe complete relaxation lattice constant of the N layer is given byα_relax(y) is D_yE_1-yThe complete relaxation lattice constant of the N layer is given by

It should be appreciated that when the lower group III-nitride ternary alloy layer of the heterojunction is the substrate or is fully relaxed on the substrate, the termBecomes zero, the group III nitride ternary alloy layer at the lower portion of the heterojunction will not exhibit piezoelectric polarization. Furthermore, when the lower group III nitride ternary alloy layer of the heterojunction is fully strained on the substrate, both layers have a lattice constant equal to that of the substrate. When the lower group III-nitride ternary alloy layer of the heterojunction is neither fully relaxed nor fully strained on the substrate, the lattice constants of both the upper group III-nitride ternary alloy layer and the lower group III-nitride ternary alloy layer are affected by the lattice constant of the substrate. When the lower group III nitride ternary alloy layer of the heterojunction is neither fully relaxed nor fully strained on the substrate, the lattice constants of the upper and lower group III nitride ternary alloy layers can be determined based on experiments using, for example, X-ray diffraction (XRD) imaging. This will involve routine experimentation by one of ordinary skill in the art.

The spontaneous polarization of the aluminum gallium nitride (AlGaN) layer is:

the spontaneous polarization of the indium gallium nitride (InGaN) layer is:

the spontaneous polarization of the indium aluminum nitride (InAlN) layer is:

the spontaneous polarization of the boron aluminum nitride (BAlN) layer is:

the spontaneous polarization of the boron nitride gallium (BGaN) layer is:

it should be appreciated that if the layer is the lower layer of a group III nitride ternary alloy heterojunction, the x subscripts in equations (6) - (10) will be the y subscripts.

As shown in the above equations (4) and (5), the determination of the piezoelectric polarization requires the piezoelectric constant e₃₁And e₃₃Applied strain due to lattice mismatch (∈)₃Or ∈₁) And crystal deformation can cause piezoelectric polarization intensity which is mainly composed of two piezoelectric constants e₃₃And e₃₁Characterized, and given by the following equation:

the piezoelectric constant, also known as the relaxation term, includes two components:is used as a fixingDetermining a clamp ion item obtained by an internal parameter u; and isIs an internal strain term caused by bond changes caused by external strain. P₃Is the microscopic polarization along the c-axis, u is an internal parameter, Z^*Is the zz component of the Born effective charge tensor, e is the electronic charge, and α is the lattice constant.

Piezoelectric constant e of aluminum gallium nitride (AlGaN) layer₃₁And e₃₃Comprises the following steps:

e₃₁(Al_xGa_1-xN)＝-0.0573x²-0.2536x-0.3582 (13)

e₃₃(Al_xGa_1-xN)＝0.3949x²+0.6324x+0.6149 (14)

piezoelectric constant e of indium gallium nitride (InGaN) layer₃₁And e₃₃Comprises the following steps:

e₃₁(In_xGa_1-xN)＝0.2396x²-0.4483x-0.3399 (15)

e₃₃(In_xGa_1-xN)＝-0.1402x²+0.5902x+0.6080 (16)

piezoelectric constant e of indium aluminum nitride (InAlN) layer₃₁And e₃₃Comprises the following steps:

e₃₁(In_xAl_1-xN)＝-0.0959x²+0.239x-0.6699 (17)

e₃₃(In_xAl_1-xN)＝0.9329x²-1.5036x+1.6443 (18)

piezoelectric constant e of boron aluminum nitride (BAlN) layer₃₁And e₃₃Comprises the following steps:

e₃₁(B_xAl_1-xN)＝1.7616x²-0.9003x-0.6016 (19)

e₃₃(B_xAl_1-xN)＝-4.0355x²+1.6836x+1.5471(20)

piezoelectric constant e of boron gallium nitride (BGaN) layer₃₁And e₃₃Comprises the following steps:

e₃₁(B_xGa_1-xN)＝0.9809x²-0.4007x-0.3104 (21)

e₃₃(B_xGa_1-xN)＝-2.1887x²+0.8174x+0.5393 (22)

it should be appreciated that if the layer is the lower layer of a group III nitride ternary alloy heterojunction, the x subscripts in equations (13) - (22) will be the y subscripts.

As shown in the above equations (4) and (5), the determination of the piezoelectric polarization further requires the elastic constant C of the upper and lower group III nitride ternary alloy layers of the heterojunction₁₃And C₃₃. These elastic constants can be determined using Vegard's law and the following binary constants. They can also be obtained by directly calculating the ternary constants.

C₁₃(B_xAl_1-xN)＝xC₁₃(BN)+(1-x)C₁₃(AlN) (23)

C₁₃(B_xGa_1-xN)＝xC₁₃(BN)+(1-x)C₁₃(GaN) (24)

C₁₃(Al_xGa_1-xN)＝xC₁₃(AlN)+(1-x)C₁₃(GaN) (25)

C₁₃(In_xGa_1-xN)＝xC₁₃(InN)+(1-x)C₁₃(GaN) (26)

C₁₃(In_xAl_1-xN)＝xC₁₃(InN)+(1-x)C₁₃(AlN) (27)

C₃₃(B_xAl_1-xN)＝xC₃₃(BN)+(1-x)C₃₃(AlN) (28)

C₃₃(B_xGa_1-xN)＝xC₃₃(BN)+(1-x)C₃₃(GaN) (29)

C₃₃(Al_xGa_1-xN)＝xC₃₃(AlN)+(1-x)C₃₃(GaN) (30)

C₃₃(In_xGa_1-xN)＝xC₃₃(InN)+(1-x)C₃₃(GaN) (31)

C₃₃(In_xAl_1-xN)＝xC₃₃(InN)+(1-x)C₃₃(AlN) (32)

As shown in equations (4) and (5) above, the determination of piezoelectric polarization also requires the lattice constant α of the upper and lower III-nitride ternary alloy layers of the heterojunction for which the cations are randomly distributed among the cation sites and the anion sites are always occupied by nitrogen atoms.

Previous studies of spontaneous polarization and piezoelectric constants of conventional group III nitride ternary alloys containing AlGaN, InGaN, and AlInN have shown that spontaneous polarization and piezoelectric constants of supercells with differently ordered cation atoms can vary greatly.a special quasi-random structure (SQS) can effectively represent the microstructure of random alloys under periodic conditions, however, a special quasi-random structure is only applicable to ternary alloys with two cations of the same composition (i.e., 50% each). on the other hand, chalcopyrite-type (CH) structures defined by two cations of one species surrounding each anion and two cations of the other species (thus 50%), and chalcopyrite-type (L Z) structures defined by three cations of one species surrounding each anion and one cation of the other species (thus 25% or 75%), can represent well the microstructure of random alloys used to calculate spontaneous polarization and piezoelectric constants.a microstructure of chalcopyrite-type (50%) and chalcopyrite-type (25%, 75%) structures is employed and then a 16 atom supercell nitride group III nitride is calculated using 0%, 25%, and 100% of the ternary group III nitride elements as follows:

the remaining values of the lattice constants for the four different compositional percentages of the group III nitride element were determined using quadratic regression, the results of which are shown in fig. 5A-5E, specifically, fig. 5A-5E show the lattice constants (a) and the concentrations of the group III nitride element for an aluminum gallium nitride (AlGaN) layer, an indium gallium nitride (InGaN) layer, an indium aluminum nitride (InAlN) layer, an aluminum boron nitride (BAlN) layer, and a gallium boron nitride (BGaN) layer, respectively, wherein the layers are in a fully relaxed state.

The above equation for calculating the difference in polarization at the interface of the heterojunction of the first group III nitride ternary alloy layer and the second group III nitride ternary alloy layer assumes that the interface of the heterojunction is a clear boundary. Although in practice there may not be a perfectly sharp boundary at the interface of the heterojunction, it is common practice to calculate the difference in polarization at the interface of the heterojunction of the two layers assuming a sharp boundary at the interface. An unclear boundary at the interface of the heterojunction will act as an additive or subtractive factor in the calculation of the difference in polarization strength. Nonetheless, since the disclosed embodiments provide a concentration range of group III nitride elements from which a particular concentration of group III nitride elements can be selected, the disclosed embodiments can be used to select from farther away from the boundary conditions (i.e., than 0.007C/m when a small difference in polarization is desired²Closer to zero and higher than 0.04C/m when large differences in polarization are desired²Of the heterojunction) to counteract the effect of an unclear boundary at the interface of the heterojunction.

As described above, the conventional polarization constant used to determine the difference in polarization at the interface of the heterojunction of two group III nitride ternary alloy layers having a wurtzite structure is based on linear interpolation of group III nitride binary elements, which may be inaccurate. Thus, conventional techniques based on calculations using these interpolated polarization constants may indicate that the interface between two III-nitride ternary alloy layers has a particular difference in polarization, while in practice, semiconductor devices constructed using the calculated values can exhibit different differences in polarization at the heterojunction interface.

Using the formulas disclosed herein, the polarization difference can be determined more accurately for any composition of the layer comprising the AlGaN, InGaN, InAlN, BAlN, and/or BGaN layers. In particular, these formulas allow for the first time the identification of the compositional range of the group III nitride element in the above-described group III nitride ternary alloy layer to achieve low polarization intensity differences (i.e., less than or equal to 0.007C/m) useful for optoelectronic devices²) Or to achieve a high difference in polarization (i.e., greater than or equal to 0.04C/m) useful for high electron mobility transistors²). The determined compositional ranges of the group III-nitride elements provide great flexibility in selecting the particular compositions of the group III-nitride elements to achieve the desired difference in polarization. For example, some of the component values in the component ranges may not be practical for practical formation of a layer having a wurtzite structure, such as a high concentration of boron, which is difficult to form in practice. Thus, in this example, it is possible to select different boron concentrations and adjust the concentration of the group III nitride element in the other layers to maintain the desired difference in polarization at the heterojunction interface. In contrast, prior to this disclosure, achieving a high or low difference in polarization at the interface of the heterojunction of the group III nitride ternary alloy layer was the best trial-and-error method to adjust the composition of the two group III nitride ternary alloy layers to achieve the desired difference in polarization.

The above discussion is with respect to certain group III nitride ternary alloys. It should be appreciated that this is intended to encompass both alloys having both group III nitride elements, as well as alloys having additional elements that may be present in insignificant concentrations due to, for example, contaminants or impurities becoming part of one or both layers during the process of forming the layers. These contaminants or impurities typically comprise less than group III nitride ternary0.1% of the total composition of the alloy layer. Further, when there are other elements in addition to the two types of group III elements in insignificant amounts including other types of group III elements, one skilled in the art also treats the group III nitride alloy as a ternary alloy. One skilled in the art would consider concentrations of 0.1% or less of an element to be insignificant amounts. Thus, for example, one skilled in the art would include Al_xGa_1-x-yIn_yA layer of N (where y ≦ 0.1%) is considered a ternary alloy because it contains an insignificant amount of indium.

The disclosed embodiments provide semiconductor devices including heterojunctions of wurtzite group III nitride ternary alloys and methods for forming such semiconductor devices. It should be understood that this description is not intended to limit the invention. On the contrary, the exemplary embodiments are intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a thorough understanding of the claimed invention. However, it will be understood by those skilled in the art that various embodiments may be practiced without such specific details.

Although the features and elements of the present exemplary embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein.

This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the subject matter, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to fall within the scope of the claims.