阅读说明：本技术 一种降低接触电阻的led外延结构及其生长方法 (LED epitaxial structure capable of reducing contact resistance and growth method thereof ) 是由 冯磊 徐平 黄胜蓝 于 2020-07-22 设计创作，主要内容包括：本发明提供一种降低接触电阻的LED外延结构,包括基板及依次层叠设置在基板上的低温GaN缓冲层、不掺杂Si的GaN层、掺杂Si的GaN层、发光层、掺杂Mg的Al型GaN层、掺杂Mg的GaN层、接触层以及ITO层,在ITO层上设置P电极,在掺杂Si的GaN层上设置N电极；接触层包括至少一层接触单层,所述接触单层由掺杂In和Mg的GaN层以及掺杂Mg的GaN层构成。本发明的LED外延结构中由掺杂In和Mg的GaN层以及掺杂Mg的GaN层构成接触层位于掺杂Mg的GaN层和ITO层之间,它和ITO接触功函数比pGaN和ITO接触功函数要低很多,独特结构的接触层能有效降低pGaN外延层和ITO的接触电阻,有效地降低驱动电压,从而提高产品的光效品质。本发明还公开一种上述LED外延结构的生长方法,工艺精简,便于工业化生产。(The invention provides an LED epitaxial structure capable of reducing contact resistance, which comprises a substrate, and a low-temperature GaN buffer layer, a GaN layer without doped Si, a GaN layer doped with Si, a light emitting layer, an Al-type GaN layer doped with Mg, a contact layer and an ITO layer which are sequentially stacked on the substrate, wherein a P electrode is arranged on the ITO layer, and an N electrode is arranged on the GaN layer doped with Si; the contact layer includes at least one contact monolayer composed of an In-and Mg-doped GaN layer and an Mg-doped GaN layer. The contact layer formed by the GaN layer doped with In and Mg and the GaN layer doped with Mg In the LED epitaxial structure is positioned between the GaN layer doped with Mg and the ITO layer, the contact work function of the contact layer with ITO is much lower than that of pGaN and ITO, the contact resistance of the pGaN epitaxial layer and ITO can be effectively reduced by the contact layer with the unique structure, the driving voltage is effectively reduced, and the light effect quality of the product is improved. The invention also discloses a growth method of the LED epitaxial structure, which is simple in process and convenient for industrial production.)

1. The utility model provides a reduce contact resistance's LED epitaxial structure which characterized in that: the GaN-based light-emitting diode comprises a substrate (1), and a low-temperature GaN buffer layer (2), a GaN layer (3) without doped Si, a GaN layer (4) doped with Si, a light-emitting layer (5), an Al-type GaN layer (6) doped with Mg, a GaN layer (7) doped with Mg, a contact layer (8) and an ITO layer (9) which are sequentially stacked on the substrate (1), wherein a P electrode (11) is arranged on the ITO layer (9), and an N electrode (12) is arranged on the GaN layer (4) doped with Si;

The contact layer (8) comprises at least one contact monolayer consisting of an In and Mg doped GaN layer and an Mg doped GaN layer.

2. The LED epitaxial structure with reduced contact resistance according to claim 1, wherein: the contact single layer is formed by sequentially laminating the In-and Mg-doped GaN layer and the Mg-doped GaN layer, and the In-and Mg-doped GaN layer is In contact with the Mg-doped GaN layer (7);

or the contact single layer is formed by sequentially laminating the Mg-doped GaN layer and the In-and Mg-doped GaN layer, and the Mg-doped GaN layer is In contact with the Mg-doped GaN layer (7).

3. The LED epitaxial structure with reduced contact resistance according to claim 2, wherein: the contact layer (8) comprises 4-60 contact single layers which are sequentially stacked.

4. The LED epitaxial structure with reduced contact resistance according to any one of claims 1 to 3, wherein: the substrate (1) is a sapphire substrate;

the thickness of the low-temperature GaN buffer layer (2) is 20-40 nm;

the thickness of the GaN layer (3) without doping SI is 2-4 μm;

the thickness of the Si-doped GaN layer (4) is 200-400 nm;

the light-emitting layer (5) is formed by 7-15 stacked light-emitting single layers, and the light-emitting single layers are formed by In of 2.5-3.5nm _xGa_(1-x)N layer and GaN layer of 8-15nm, x is 0.20-0.25;

the thickness of the Mg-doped Al-type GaN layer (6) is 50-100 nm;

the thickness of the Mg-doped GaN layer (7) is 50-100 nm.

5. A growth method of an LED epitaxial structure for reducing contact resistance is characterized in that: comprises growing a GaN layer (7) doped with Mg and a contact layer (8);

the growing of the Mg-doped GaN layer (7) is specifically: keeping the pressure of the reaction cavity at 400-₃20-100sccm of TMGa, 100-₂1000-Cp of 3000sccm₂Mg, continuously growing a GaN layer (7) doped with Mg with the concentration of 50-100nm, wherein the doping concentration of Mg is 1E19-1E 20;

the growth contact layer (8) comprises a growth In and Mg-doped GaN layer (8a) and a growth Mg-doped GaN layer (8 b); the growth of the In-and Mg-doped GaN layer (8a) is specifically: keeping the pressure of the reaction chamber at 300-₂5000-7000sccm Cp₂Mg and TMIn of 1000-2000sccm, and growing a GaN layer (8a) doped with In and Mg with the thickness of 1-2 nm; the growth of the Mg-doped GaN layer (8b) is specifically: keeping the pressure of the reaction cavity at 300-600mbar and the temperature at 750-850 ℃, introducing 10-20sccm TMGa and 100-130L/min N ₂And 5000-7000sccm Cp₂And growing a 1-2nm Mg-doped GaN layer (8b), wherein the doping concentration of Mg is 1E21-5E 21.

6. The growing method according to claim 5, wherein: the method comprises the following steps of processing a substrate (1), growing a low-temperature GaN buffer layer (2), growing a GaN layer (3) without doped Si, growing a GaN layer (4) doped with Si, growing a light emitting layer (5), growing an Al type GaN layer (6) doped with Mg, manufacturing an ITO layer (9), manufacturing a P electrode (11) on the ITO layer (9), and manufacturing an N electrode (12) on the GaN layer (4) doped with Si;

the substrate (1) is specifically treated by: introducing H of 100L/min-130L/min under the hydrogen atmosphere of 1000-1100 DEG C₂The pressure of the reaction cavity is kept at 100-300mbar, and the sapphire substrate is processed for 8-10 minutes;

the growing low-temperature GaN buffer layer (2) is specifically as follows: cooling to 500-600 ℃, keeping the pressure of the reaction cavity at 300-20000 sccm, and introducing NH with the flow rate of 10000-20000sccm₃TMGa of 50-100sccm and H of 100-130L/min₂Growing a low-temperature GaN buffer layer (2) with the thickness of 20-40nm on the sapphire substrate;

the GaN layer (3) without doped Si is grown specifically as follows: raising the temperature to 1000-1200 ℃, keeping the pressure of the reaction cavity at 600mbar and introducing NH with the flow rate of 30000- ₃200-400sccm TMGa and 100-130L/min H₂Continuously growing a GaN layer (3) which is not doped with Si and has the thickness of 2-4 mu m;

the growth of the Si-doped GaN layer (4) is specifically: keeping the temperature at 1000-1200 ℃ and the pressure of the reaction chamber at 300-₃200-400sccm TMGa, 100-130L/min H₂And SiH of 20-50sccm₄Continuously growing a 3-4 μm Si-doped GaN layer (4) with a Si doping concentration of 5E18 atoms/cm³-1E19atoms/cm³；

Growing the light-emitting layer (5) comprises repeatedly growing 7-15 light-emitting monolayers, growing the light-emitting monolayers comprising growing In_xGa_(1-x)An N layer (5a) and a growth GaN layer (5 b); growing In_xGa_(1-x)The N layer (5a) is specifically: keeping the pressure of the reaction cavity at 300-400mbar and the temperature at 700-750 ℃, and introducing NH with the flow rate of 50000-70000sccm₃20-40sccm of TMGa, 1500-₂In of 2.5-3.5nm is grown_xGa_(1-x)An N layer (5a), wherein x is 0.20-0.25, and the light-emitting wavelength is 450-455 nm; growing a GaN layer(5b) The method comprises the following steps: raising the temperature to 750-850 ℃, keeping the pressure of the reaction cavity at 300-400mbar, and introducing NH with the flow rate of 50000-70000sccm₃20-100sccm of TMGa and 100-130L/min of N₂Growing a GaN layer (5b) with the thickness of 8-15 nm;

the growing Mg-doped Al-type GaN layer (6) is specifically as follows: keeping the pressure of the reaction cavity at 200-400mbar and the temperature at 900-950 ℃, and introducing NH with the flow rate of 50000-70000sccm ₃TMGa 30-60sccm, H100-130L/min₂100-130sccm TMAl and 1000-1300sccm Cp2Mg, and continuously growing a 50-100nm Mg-doped Al-type GaN layer (6), wherein: the doping concentration of Al is 1E20-3E20, and the doping concentration of Mg is 1E19-1E 20.

Technical Field

The invention relates to the technical field of LEDs, in particular to an LED epitaxial structure capable of reducing contact resistance and a growth method thereof.

Background

The LED is solid illumination, has the advantages of small volume, low power consumption, long service life, high brightness, environmental protection, firmness, durability and the like, is accepted by consumers, and the scale of domestic LED production is gradually enlarged; the market demands that the product quality is higher and higher, and customers pay attention to the LED more power-saving, the brightness is higher, the lighting effect is better, and therefore higher requirements are provided for the epitaxial growth of the LED.

The requirements of driving voltage and brightness of a high-power device are key points of current market demands, a P layer and ITO (indium tin oxide) are directly contacted in the traditional epitaxial growth method of the LED, and the contact work function of the P layer and the ITO is very large, so that the contact resistance is large, the driving voltage of the LED is high, and the lighting effect quality of a product is influenced.

Therefore, the design of the LED epitaxial structure for reducing the contact resistance and the growth method thereof have important significance.

Disclosure of Invention

The invention discloses an LED epitaxial structure for reducing contact resistance, which aims to solve the technical problems of large contact resistance and high LED driving voltage caused by direct contact between a P layer and ITO in the prior art, and the specific technical scheme is as follows:

an LED epitaxial structure capable of reducing contact resistance comprises a substrate, and a low-temperature GaN buffer layer, a GaN layer without doped Si, a GaN layer doped with Si, a light emitting layer, an Al-type GaN layer doped with Mg, a contact layer and an ITO layer which are sequentially stacked on the substrate, wherein a P electrode is arranged on the ITO layer, and an N electrode is arranged on the GaN layer doped with Si;

The contact layer includes at least one contact monolayer composed of an In-and Mg-doped GaN layer and an Mg-doped GaN layer.

Preferably, In the above technical solution, the contact single layer is formed by sequentially stacking the In-and Mg-doped GaN layer and the Mg-doped GaN layer, and the In-and Mg-doped GaN layer is In contact with the Mg-doped GaN layer;

or the contact single layer is formed by sequentially laminating the Mg-doped GaN layer and the In-and Mg-doped GaN layers, and the Mg-doped GaN layer is In contact with the Mg-doped GaN layer.

Preferably, in the above technical solution, the contact layer includes 4 to 60 contact monolayers sequentially stacked.

Preferably, in the above technical solution, the substrate is a sapphire substrate; the thickness of the low-temperature GaN buffer layer is 20-40 nm; the thickness of the GaN layer without doping SI is 2-4 μm; the thickness of the Si-doped GaN layer is 200-400 nm; the light-emitting layer is formed by 7-15 stacked light-emitting single layers, and the light-emitting single layers are formed by 2.5-3.5nm of In_xGa_(1-x)N layer and GaN layer of 8-15nm, x is 0.20-0.25; the thickness of the Mg-doped Al-type GaN layer is 50-100 nm; the thickness of the Mg-doped GaN layer is 50-100 nm.

The contact layer formed by the GaN layer doped with In and Mg and the GaN layer doped with Mg In the LED epitaxial structure is positioned between the GaN layer doped with Mg and the ITO layer, the contact work function of the contact layer with ITO is much lower than that of pGaN and ITO, the contact resistance of the pGaN epitaxial layer and ITO can be effectively reduced by the contact layer with the unique structure, the driving voltage is effectively reduced, and the light effect quality of the product is improved.

The invention discloses a growth method of the LED epitaxial structure, which specifically comprises the steps of growing a GaN layer doped with Mg and a contact layer;

the growth of the Mg-doped GaN layer is specifically: keeping the pressure of the reaction cavity at 400-₃20-100sccm of TMGa, 100-₂1000-Cp of 3000sccm₂Mg, doped Mg with 50-100nm of continuous growthThe GaN layer of (1), wherein the doping concentration of Mg is 1E19-1E 20;

the contact layer is grown and comprises a GaN layer doped with In and Mg and a GaN layer doped with Mg; the growth of the In and Mg doped GaN layer is specifically: keeping the pressure of the reaction chamber at 300-₂5000-7000sccm Cp₂Mg and 1000-2000sccm TMIn, and growing a GaN layer doped with In and Mg with the thickness of 1-2 nm; the growth of the Mg-doped GaN layer is specifically: keeping the pressure of the reaction cavity at 300-600mbar and the temperature at 750-850 ℃, introducing 10-20sccm TMGa and 100-130L/min N ₂And 5000-7000sccm Cp₂And growing a 1-2nm Mg-doped GaN layer, wherein the doping concentration of Mg is 1E21-5E 21.

Preferably, the method further comprises the steps of processing the substrate, growing a low-temperature GaN buffer layer, growing a GaN layer without doped Si, growing a GaN layer doped with Si, growing a light emitting layer, growing an Al-type GaN layer doped with Mg, manufacturing an ITO layer, manufacturing a P electrode on the ITO layer and manufacturing an N electrode on the GaN layer doped with Si;

the substrate treatment specifically comprises: introducing H of 100L/min-130L/min under the hydrogen atmosphere of 1000-1100 DEG C₂The pressure of the reaction cavity is kept at 100-300mbar, and the sapphire substrate is processed for 8-10 minutes;

the growing of the low-temperature GaN buffer layer is specifically as follows: cooling to 500-600 ℃, keeping the pressure of the reaction cavity at 300-20000 sccm, and introducing NH with the flow rate of 10000-20000sccm₃TMGa of 50-100sccm and H of 100-130L/min₂Growing a low-temperature GaN buffer layer with the thickness of 20-40nm on the sapphire substrate;

the growth of the Si-undoped GaN layer is specifically as follows: raising the temperature to 1000-1200 ℃, keeping the pressure of the reaction cavity at 600mbar and introducing NH with the flow rate of 30000-₃200-400sccm TMGa and 100-130L/min H₂Continuously growing a GaN layer which is not doped with Si and has the thickness of 2-4 mu m;

The growth of the Si-doped GaN layer is specifically: keeping the temperature at 1000-1200 ℃ and the pressure of the reaction chamber at 300-₃200-400sccm TMGa, 100-130L/min H₂And SiH of 20-50sccm₄Continuously growing a 3-4 μm Si-doped GaN layer with a Si doping concentration of 5E18 atoms/cm³-1E19atoms/cm³；

Growing the light emitting layer comprises repeatedly growing 7-15 light emitting monolayers, growing the light emitting monolayers comprises growing In_xGa_(1-x)N layer and growth GaN layer; the growing of the InxGa (1-x) N layer is specifically as follows: keeping the pressure of the reaction cavity at 300-400mbar and the temperature at 700-750 ℃, and introducing NH with the flow rate of 50000-70000sccm₃20-40sccm of TMGa, 1500-₂In of 2.5-3.5nm is grown_xGa_(1-x)N layer, x is 0.20-0.25, the luminescence wavelength is 450-; the growing GaN layer is specifically: raising the temperature to 750-850 ℃, keeping the pressure of the reaction cavity at 300-400mbar, and introducing NH with the flow rate of 50000-70000sccm₃20-100sccm of TMGa and 100-130L/min of N₂Growing a GaN layer with the thickness of 8-15 nm;

the growing of the Mg-doped Al-type GaN layer is specifically as follows: keeping the pressure of the reaction cavity at 200-400mbar and the temperature at 900-950 ℃, and introducing NH with the flow rate of 50000-70000sccm₃TMGa 30-60sccm, H100-130L/min ₂100-130sccm TMAl and 1000-1300sccm Cp2Mg, and continuously growing a 50-100nm Mg-doped Al-type GaN layer, wherein: the doping concentration of Al is 1E20-3E20, and the doping concentration of Mg is 1E19-1E 20.

The growth method has the advantages of simplified steps, easily controlled parameters, capability of being carried out by adopting the existing epitaxial manufacturing equipment, contribution to industrial production, reduction in the voltage of the finally obtained product, improvement in the light efficiency and improvement in the quality of the product.

In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic view of an epitaxial structure of an LED in example 1;

FIG. 2 is a schematic diagram of an epitaxial structure of an LED in a comparative example;

wherein: 1. substrate, 2, low-temperature GaN buffer layer, 3, GaN layer not doped with Si, 4, GaN layer doped with Si, 5, light-emitting layer, 5a, In_xGa_(1-x)N layer, 5b, GaN layer, 6, Mg-doped Al-type GaN layer, 7, Mg-doped GaN layer, 8, contact layer, 8a, In-and Mg-doped GaN layer, 8b, Mg-doped GaN layer, 9, ITO layer, 10, protective layer, 11, P electrode, 12 and N electrode.

Detailed Description

Embodiments of the invention will be described in detail below with reference to the drawings, but the invention can be implemented in many different ways, which are defined and covered by the claims.