Gallium nitride-based light emitting diode epitaxial wafer and preparation method thereof

文档序号:117386 发布日期:2021-10-19 浏览:50次 中文

阅读说明:本技术 氮化镓基发光二极管外延片及其制备方法 (Gallium nitride-based light emitting diode epitaxial wafer and preparation method thereof ) 是由 王群 郭炳磊 葛永晖 王江波 董彬忠 李鹏 于 2021-05-21 设计创作,主要内容包括:本公开提供了一种氮化镓基发光二极管外延片及其制备方法,属于半导体技术领域。发光二极管外延片包括衬底、以及依次层叠在衬底上的缓冲层、未掺杂的氮化镓层、N型层、有源层、复合P型层以及P型接触层;复合P型层包括依次层叠在有源层上的第一复合层和第二复合层,第一复合层为氮化镓层,第二复合层为P型氮化镓层,有源层的与第一复合层接触的一面上具有多个凸起,且多个凸起穿过第一复合层,位于第二复合层内,多个凸起为氧化镓材料。该发光二极管外延片可以减少Mg的掺杂,改善小电流下空穴的扩展和有效注入,提高外延片的发光效率。(The disclosure provides a gallium nitride-based light emitting diode epitaxial wafer and a preparation method thereof, belonging to the technical field of semiconductors. The light-emitting diode epitaxial wafer comprises a substrate, and a buffer layer, an undoped gallium nitride layer, an N-type layer, an active layer, a composite P-type layer and a P-type contact layer which are sequentially stacked on the substrate; the composite P-type layer comprises a first composite layer and a second composite layer which are sequentially stacked on the active layer, the first composite layer is a gallium nitride layer, the second composite layer is a P-type gallium nitride layer, a plurality of bulges are arranged on one surface of the active layer, which is in contact with the first composite layer, and the bulges penetrate through the first composite layer and are located in the second composite layer, and the bulges are made of gallium oxide materials. The light-emitting diode epitaxial wafer can reduce the doping of Mg, improve the expansion and effective injection of a cavity under low current and improve the luminous efficiency of the epitaxial wafer.)

1. The GaN-based light-emitting diode epitaxial wafer is characterized by comprising a substrate, and a buffer layer, an undoped GaN layer, an N-type layer, an active layer, a composite P-type layer and a P-type contact layer which are sequentially stacked on the substrate;

the composite P-type layer comprises a first composite layer and a second composite layer which are sequentially stacked on the active layer, the first composite layer is a gallium nitride layer, the second composite layer is a P-type gallium nitride layer, a plurality of bulges are arranged on one surface of the active layer, which is in contact with the first composite layer, and penetrate through the first composite layer and are positioned in the second composite layer, and the bulges are made of gallium oxide materials.

2. The light emitting diode epitaxial wafer according to claim 1, wherein the protrusions are rectangular parallelepiped, trapezoidal or pyramidal.

3. The light-emitting diode epitaxial wafer according to claim 2, wherein the height of each protrusion is 5-10 nm.

4. The light-emitting diode epitaxial wafer according to claim 1, wherein the thickness of the first composite layer is 3-8 nm.

5. The light-emitting diode epitaxial wafer according to claim 1, wherein the second composite layer comprises a first sub-layer and a second sub-layer sequentially stacked on the first composite layer, the doping concentration of Mg in the first sub-layer is greater than that in the second sub-layer, the thickness of the first sub-layer is 2-5 nm, and the thickness of the second sub-layer is 5-50 nm.

6. The light-emitting diode epitaxial wafer according to claim 5, wherein the doping concentration of Mg in the first sub-layer is 1 x 1020cm-3~4*1020cm-3Doping concentration of Mg in the second sublayerIs 1 x 1019cm-3~6*1019cm-3

7. A preparation method of a gallium nitride-based light emitting diode epitaxial wafer is characterized by comprising the following steps:

providing a substrate;

growing a buffer layer, an undoped gallium nitride layer, an N-type layer and an active layer on the substrate in sequence;

forming a plurality of protrusions on the active layer, the plurality of protrusions being of gallium oxide material;

growing a composite P-type layer on the active layer, wherein the composite P-type layer comprises a first composite layer and a second composite layer which are sequentially laminated on the active layer, the first composite layer is a gallium nitride layer, the second composite layer is a P-type gallium nitride layer, and the plurality of protrusions penetrate through the first composite layer and are positioned in the second composite layer;

and growing a P-type contact layer on the composite P-type layer.

8. The method of claim 7, wherein the forming a plurality of protrusions on the active layer comprises:

preparing a mask plate on the active layer, wherein the mask plate is provided with a pattern;

growing a gallium nitride layer in the pattern of the mask plate to copy the pattern on the mask plate onto the active layer and form a plurality of bulges on the active layer;

and removing the mask plate, and carrying out oxygen plasma treatment on the plurality of protrusions to change the plurality of protrusions from gallium nitride into gallium oxide materials.

9. The method of claim 8, wherein the subjecting the plurality of protrusions to an oxygen plasma treatment comprises:

and placing the epitaxial wafer with the plurality of protrusions into plasma processing equipment, introducing ozone into the plasma processing equipment, controlling the temperature in the plasma processing equipment to be 300-600 ℃ and the radio frequency power to be 15-50W, and performing oxygen plasma processing on the surface of the P-type gallium nitride layer for 30-500 s to bond the gallium nitride materials with oxygen to form gallium oxide materials.

10. The method according to claim 7, wherein the second composite layer comprises a first sub-layer and a second sub-layer sequentially stacked on the first composite layer, and the growing the P-type layer on the active layer comprises:

growing the first composite layer on the active layer;

growing the first sub-layer on the first composite layer, wherein the thickness of the first sub-layer is 2-5 nm;

and growing the second sublayer on the first sublayer, wherein the thickness of the second sublayer is 5-50 nm, and the doping concentration of Mg in the first sublayer is greater than that of Mg in the second sublayer.

Technical Field

The disclosure relates to the technical field of semiconductors, in particular to a gallium nitride-based light emitting diode epitaxial wafer and a preparation method thereof.

Background

A Light Emitting Diode (LED) is a semiconductor Diode that can convert electrical energy into Light energy. The LED has the advantages of high efficiency, energy conservation and environmental protection, and has wide application in the fields of traffic indication, outdoor full-color display and the like.

At present, the gallium nitride-based LED receives more and more attention and research, and the epitaxial structure main body of the gallium nitride-based LED is as follows: a substrate (sapphire substrate), a gallium nitride or aluminum-doped gallium nitride buffer layer, an undoped GaN layer, an N-type layer, a current active layer, a P-type layer, and a P-type contact layer. Wherein, the P-type layer and the P-type contact layer are both Mg-doped gallium nitride layers. When current flows, electrons in the N-type region and holes in the P-type region enter the active layer and recombine to emit visible light in a required waveband.

In the process of implementing the invention, the inventor finds that the prior art has at least the following problems:

because of the low effective ionization rate of Mg, more Mg is doped to reach the required effective concentration. Therefore, Mg heavy doping of the P-type layer is often required to increase the effective concentration of holes. However, additional defects and impurities are introduced by heavy doping of Mg, so that holes with low mobility are more difficult to inject, and particularly in a micro display LED, the problems of low working current and low hole injection efficiency are more prominent.

Disclosure of Invention

The embodiment of the disclosure provides a gallium nitride-based light emitting diode epitaxial wafer and a preparation method thereof, which can reduce the doping of Mg, improve the expansion and effective injection of a cavity under a small current and improve the luminous efficiency of the epitaxial wafer. The technical scheme is as follows:

the embodiment of the disclosure provides a gallium nitride-based light emitting diode epitaxial wafer, which comprises a substrate, and a buffer layer, an undoped gallium nitride layer, an N-type layer, an active layer, a composite P-type layer and a P-type contact layer which are sequentially stacked on the substrate;

the composite P-type layer comprises a first composite layer and a second composite layer which are sequentially stacked on the active layer, the first composite layer is a gallium nitride layer, the second composite layer is a P-type gallium nitride layer, a plurality of bulges are arranged on one surface of the active layer, which is in contact with the first composite layer, and penetrate through the first composite layer and are positioned in the second composite layer, and the bulges are made of gallium oxide materials.

Optionally, the protrusion is a cuboid, a trapezoid, or a cone.

Optionally, the height of each protrusion is 5-10 nm.

Optionally, the thickness of the first composite layer is 3-8 nm.

Optionally, the second composite layer includes a first sub-layer and a second sub-layer sequentially stacked on the first composite layer, a doping concentration of Mg in the first sub-layer is greater than a doping concentration of Mg in the second sub-layer, a thickness of the first sub-layer is 2-5 nm, and a thickness of the second sub-layer is 5-50 nm.

Optionally, the doping concentration of Mg in the first sublayer is 1 x 1020cm-3~4*1020cm-3The doping concentration of Mg in the second sub-layer is 1 x 1019cm-3~6*1019cm-3

In another aspect, a method for preparing a gallium nitride-based light emitting diode epitaxial wafer is provided, the method comprising:

providing a substrate;

growing a buffer layer, an undoped gallium nitride layer, an N-type layer and an active layer on the substrate in sequence;

forming a plurality of protrusions on the active layer, the plurality of protrusions being of gallium oxide material;

growing a composite P-type layer on the active layer, wherein the composite P-type layer comprises a first composite layer and a second composite layer which are sequentially laminated on the active layer, the first composite layer is a gallium nitride layer, the second composite layer is a P-type gallium nitride layer, and the plurality of protrusions penetrate through the first composite layer and are positioned in the second composite layer;

and growing a P-type contact layer on the composite P-type layer.

Optionally, the forming a plurality of protrusions on the active layer includes:

preparing a mask plate on the active layer, wherein the mask plate is provided with a pattern;

growing a gallium nitride layer in the pattern of the mask plate to copy the pattern on the mask plate onto the active layer and form a plurality of bulges on the active layer;

and removing the mask plate, and carrying out oxygen plasma treatment on the plurality of protrusions to change the plurality of protrusions from gallium nitride into gallium oxide materials.

Optionally, the performing oxygen plasma treatment on the plurality of protrusions includes:

and placing the epitaxial wafer with the plurality of protrusions into plasma processing equipment, introducing ozone into the plasma processing equipment, controlling the temperature in the plasma processing equipment to be 300-600 ℃ and the radio frequency power to be 15-50W, and performing oxygen plasma processing on the surface of the P-type gallium nitride layer for 30-500 s to bond the gallium nitride materials with oxygen to form gallium oxide materials.

Optionally, the second composite layer includes a first sub-layer and a second sub-layer sequentially stacked on the first composite layer, and the growing the P-type layer on the active layer includes:

growing the first composite layer on the active layer;

growing the first sub-layer on the first composite layer, wherein the thickness of the first sub-layer is 2-5 nm;

and growing the second sublayer on the first sublayer, wherein the thickness of the second sublayer is 5-50 nm, and the doping concentration of Mg in the first sublayer is greater than that of Mg in the second sublayer.

The technical scheme provided by the embodiment of the disclosure has the following beneficial effects:

the effective injection of carriers is realized by arranging a composite P-type layer, wherein the composite P-type layer comprises a first composite layer and a second composite layer. The first composite layer is a gallium nitride layer, and the gallium nitride material is beneficial to the expansion and injection of holes. The second composite layer is a P-type gallium nitride layer which is a main hole providing layer and is used for providing holes. The active layer is provided with a plurality of bulges on the surface contacting with the first composite layer, and the bulges are made of gallium oxide materials, so that the band gap of the gallium oxide is wide, the planar expansion of a cavity is favorably realized, the lattice stress is released, and the crystal quality of the composite P-type layer is improved. And the plurality of bulges penetrate through the first composite layer and are positioned in the second composite layer, so that the plurality of bulges can be used as a plurality of transmission channels, partial holes provided by the second composite layer can be transmitted to the active layer through the plurality of channels, the hole transmission with different dimensionalities is regulated and controlled, and the hole injection efficiency is improved. And only the second composite layer in the composite P-type layer is doped with Mg, so that the doping of Mg in the P-type layer can be reduced, the expansion and effective injection of holes under low current are improved, and the luminous efficiency of the epitaxial wafer is improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a gallium nitride-based light emitting diode epitaxial wafer according to an embodiment of the present disclosure;

fig. 2 is a flowchart of a method for manufacturing an epitaxial wafer of a gallium nitride-based light emitting diode according to an embodiment of the present disclosure;

fig. 3 is a flowchart of another method for manufacturing an epitaxial wafer of a gallium nitride-based light emitting diode according to an embodiment of the present disclosure.

Detailed Description

To make the objects, technical solutions and advantages of the present disclosure more apparent, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of a gan-based led epitaxial wafer according to an embodiment of the present disclosure, and as shown in fig. 1, the led epitaxial wafer includes a substrate 1, and a buffer layer 2, an undoped gan layer 3, an N-type layer 4, an active layer 5, a composite P-type layer 6, and a P-type contact layer 7 sequentially stacked on the substrate 1.

The composite P-type layer 6 includes a first composite layer 61 and a second composite layer 62 sequentially laminated on the active layer. The first composite layer 61 is a gallium nitride layer, the second composite layer 62 is a P-type gallium nitride layer, the active layer 5 has a plurality of protrusions 6a on the surface contacting with the first composite layer 61, and the plurality of protrusions 6a penetrate through the first composite layer 61 and are located in the second composite layer 62, and the plurality of protrusions 6a are all gallium oxide materials.

The embodiment of the disclosure realizes effective injection of carriers by arranging the composite P-type layer, wherein the composite P-type layer comprises a first composite layer and a second composite layer. The first composite layer is a gallium nitride layer, and the gallium nitride material is beneficial to the expansion and injection of holes. The second composite layer is a P-type gallium nitride layer which is a main hole providing layer and is used for providing holes. The active layer is provided with a plurality of bulges on the surface contacting with the first composite layer, and the bulges are made of gallium oxide materials, so that the band gap of the gallium oxide is wide, the planar expansion of a cavity is favorably realized, the lattice stress is released, and the crystal quality of the composite P-type layer is improved. And the plurality of bulges penetrate through the first composite layer and are positioned in the second composite layer, so that the plurality of bulges can be used as a plurality of transmission channels, partial holes provided by the second composite layer can be transmitted to the active layer through the plurality of channels, the hole transmission with different dimensionalities is regulated and controlled, and the hole injection efficiency is improved. And only the second composite layer in the composite P-type layer is doped with Mg, so that the doping of Mg in the P-type layer can be reduced, the expansion and effective injection of holes under low current are improved, and the luminous efficiency of the epitaxial wafer is improved.

Alternatively, the projections 6a are rectangular parallelepiped, trapezoidal body, or pyramidal body.

Wherein, when arch 6a is the cuboid, the light-emitting effect of chip is better. The trapezoidal body and the cone are convenient to manufacture, and the trapezoidal body can provide different crystal faces for epitaxial growth, so that defects are reduced, and stress is relieved. The projections 6a shown in fig. 1 of the embodiment of the present disclosure are rectangular parallelepipeds.

Optionally, the height of each protrusion 6a is 5-10 nm.

Because the Mo source is difficult to deposit among the protrusions, if the height of each protrusion 6a is too high, the first composite layer and the second composite layer are difficult to heal and grow, so that the plurality of protrusions 6a cannot be covered, and the finally grown epitaxial wafer has uneven appearance; if the height of each protrusion 6a is too low, the effect of improving the injection of holes cannot be obtained.

Optionally, the thickness of the first composite layer 61 is 3 to 8 nm. If the thickness of the first composite layer 61 is too thin, the thickness of the second composite layer 62 needs to be set thicker to ensure the leveling effect for the plurality of protrusions. The second composite layer 62 is a P-type GaN layer, and if the thickness is too thick, additional defects and impurities are introduced, thereby reducing Mg implantation. Therefore, setting the thickness of the first composite layer 61 within the above value range can improve the crystal quality of the grown composite P-type layer.

Alternatively, the second composite layer 62 includes a first sub-layer 621 and a second sub-layer 622 sequentially laminated on the first composite layer 61. The doping concentration of Mg in the first sub-layer 621 is greater than that of Mg in the second sub-layer 622, the thickness of the first sub-layer 621 ranges from 2 nm to 5nm, and the thickness of the second sub-layer 622 ranges from 5nm to 50 nm.

By arranging the second composite layer in a structure comprising two sub-layers, wherein the first sub-layer is a heavily Mg-doped layer, the main hole providing layer. And the second sublayer is in contact with the P-type contact layer, and the doping concentration of Mg in the P-type contact layer is lower, so that the doping concentration of Mg in the second sublayer is lower, and a transition effect can be realized. Meanwhile, the second sublayer can also be used as a hole accumulation layer to provide continuous hole supply.

Optionally, the doping concentration of Mg in the first sub-layer 621 is 1 × 1020cm-3~4*1020cm-3The doping concentration of Mg in the second sub-layer 622 is 1 x 1019cm-3~6*1019cm-3

Since Mg is doped as an impurity, if the doping concentration of Mg in the first sublayer is too high, the crystal quality of the grown composite P-type layer 6 may be poor, and even cracks may be generated. Meanwhile, the doping concentration of Mg in the first sub-layer and the second sub-layer is too low to provide sufficient holes. Therefore, when the doping concentration of Mg in the first sublayer and the second sublayer is within the value range, the crystal quality of the finally formed composite P-type layer can be ensured, and meanwhile, the effect of providing holes is ensured.

Alternatively, the substrate 1 is a sapphire substrate, a Si or SiC substrate.

Optionally, the buffer layer 2 is a GaN layer with a thickness of 15-35 nm.

Optionally, the thickness of the undoped GaN layer 3 is 1-5 um.

Optionally, the N-type layer 4 is a Si-doped GaN layer with a thickness of 1um to 2 um. The doping concentration of Si in the N-type layer 4 may be 1018cm-3~1020cm-3

Optionally, the active layer 5 comprises n InGaN well layers and n GaN barrier layers alternately grown in cycles, and n is greater than or equal to 2 and less than or equal to 10. And n is a positive integer. The thickness of each InGaN well layer is 2-3 nm, and the thickness of each GaN barrier layer is 7-10 nm.

Optionally, the P-type contact layer 7 is a Mg-doped gallium nitride layer with a thickness of 10-25 nm and a Mg doping concentration of 5 x 1019cm-3~1*1020cm-3

Fig. 2 is a flowchart of a method for preparing a gallium nitride-based light emitting diode epitaxial wafer according to an embodiment of the present disclosure, and as shown in fig. 2, the method includes:

step 201, a substrate is provided.

Illustratively, the substrate may be a sapphire, Si, or SiC substrate.

Step 202, growing a buffer layer, an undoped gallium nitride layer, an N-type layer and an active layer on the substrate in sequence.

Wherein, the buffer layer is the GaN layer, and thickness is 15 ~ 35 nm. The thickness of the undoped GaN layer is 1-5 um. The N-type layer is a GaN layer doped with Si and has a thickness of 1 um-2 um. The doping concentration of Si in the N-type layer may be 1018cm-3~1020cm-3

The active layer comprises n InGaN well layers and n GaN barrier layers which alternately grow in cycles, wherein n is more than or equal to 2 and less than or equal to 10. And n is a positive integer.

Illustratively, the thickness of each InGaN well layer is 2-3 nm, and the thickness of each GaN barrier layer is 7-10 nm.

Step 203, forming a plurality of protrusions on the active layer.

Wherein, the plurality of bulges are made of gallium oxide materials.

Step 204, a composite P-type layer is grown on the active layer.

The composite P-type layer comprises a first composite layer and a second composite layer which are sequentially stacked on the active layer, the first composite layer is a gallium nitride layer, the second composite layer is a P-type gallium nitride layer, a plurality of bulges are arranged on one surface of the active layer, which is in contact with the first composite layer, and the bulges penetrate through the first composite layer and are positioned in the second composite layer.

And step 205, growing a P-type contact layer on the composite P-type layer.

The embodiment of the disclosure realizes effective injection of carriers by arranging the composite P-type layer, wherein the composite P-type layer comprises a first composite layer and a second composite layer. The first composite layer is a gallium nitride layer, and the gallium nitride material is beneficial to the expansion and injection of holes. The second composite layer is a P-type gallium nitride layer which is a main hole providing layer and is used for providing holes. The active layer is provided with a plurality of bulges on the surface contacting with the first composite layer, and the bulges are made of gallium oxide materials, so that the band gap of the gallium oxide is wide, the planar expansion of a cavity is favorably realized, the lattice stress is released, and the crystal quality of the composite P-type layer is improved. And the plurality of bulges penetrate through the first composite layer and are positioned in the second composite layer, so that the plurality of bulges can be used as a plurality of transmission channels, partial holes provided by the second composite layer can be transmitted to the active layer through the plurality of channels, the hole transmission with different dimensionalities is regulated and controlled, and the hole injection efficiency is improved. And only the second composite layer in the composite P-type layer is doped with Mg, so that the doping of Mg in the P-type layer can be reduced, the expansion and effective injection of holes under low current are improved, and the luminous efficiency of the epitaxial wafer is improved.

Fig. 3 is a flowchart of another method for preparing an epitaxial wafer of a gallium nitride-based light emitting diode according to an embodiment of the present disclosure, and as shown in fig. 3, the method for preparing the epitaxial wafer of the gallium nitride-based light emitting diode includes:

step 301, a substrate is provided.

The substrate can be a sapphire flat sheet substrate.

Further, step 301 may further include:

controlling the temperature to be 1000-1200 ℃, and annealing the substrate for 6-10 minutes in a hydrogen atmosphere;

the substrate is subjected to a nitridation process.

The surface of the substrate is cleaned through the steps, impurities are prevented from being doped into the epitaxial wafer, and the growth quality of the epitaxial wafer is improved.

In this embodiment, a Veeco K465i or C4 or RB MOCVD (Metal Organic Chemical Vapor Deposition) apparatus is used to realize the epitaxial wafer growth method. By using high-purity H2(Hydrogen) or high purity N2(Nitrogen) or high purity H2And high purity N2The mixed gas of (2) is used as a carrier gas, high-purity NH3As the nitrogen source, trimethyl gallium (TMGa) and triethyl gallium (TEGa) as gallium sources, trimethyl indium (TMIn) as indium source, silane (SiH4) as N-type dopant, i.e., Si source, trimethyl aluminum (TMAl) as aluminum source, and magnesium diclocide (CP)2Mg) as a P-type dopant, i.e., a Mg source. The pressure in the reaction chamber is 100-600 torr.

Step 302, growing a buffer layer on the substrate.

Illustratively, the temperature of the reaction chamber is controlled to be 400-600 ℃, the pressure is controlled to be 200-500 torr, and a buffer layer with the thickness of 15-35 nm is grown.

Step 303, performing in-situ annealing treatment on the buffer layer.

Illustratively, the temperature of the reaction chamber is controlled to be 1000-1200 ℃, the pressure is 100-300 mbar, and the nucleation layer is subjected to in-situ annealing treatment for 5-10 minutes.

Step 304, growing an undoped gallium nitride layer on the buffer layer.

Illustratively, the temperature of the reaction chamber is controlled to be 1000-1100 ℃, the pressure is controlled to be 100-500 torr, and an undoped GaN layer with the thickness of 1-5 um is grown.

Step 305, an N-type layer is grown on the undoped gallium nitride layer.

Wherein, the thickness of the N-type layer can be 1-5 um, and the doping concentration of Si in the N-type layer can be 1018/cm3~1020/cm3

Illustratively, the temperature in the reaction chamber is controlled to be 1000-1200 ℃, the pressure is controlled to be 100-500 torr, and an N-type layer with the thickness of 1-5 um is grown on the undoped GaN layer.

Step 306, an active layer is grown on the N-type layer.

The active layer comprises n InGaN well layers and n GaN barrier layers which alternately grow in cycles, wherein n is more than or equal to 2 and less than or equal to 10. And n is a positive integer.

Optionally, the thickness of each InGaN well layer is 2-3 nm, and the thickness of each GaN barrier layer is 7-10 nm.

Step 307, forming a plurality of bumps on the active layer.

Wherein, the plurality of bulges are made of gallium oxide materials.

Optionally, the protrusions are cuboids, trapezoids, or pyramids.

Illustratively, step 307 may comprise:

firstly, preparing a mask on an active layer, wherein the mask has a pattern.

Wherein the mask can be SiO2A coating layer of (2).

And secondly, growing a gallium nitride layer in the pattern of the mask plate to copy the pattern on the mask plate onto the active layer and form a plurality of bulges on the active layer.

And thirdly, removing the mask and carrying out oxygen plasma treatment on the plurality of protrusions to change the plurality of protrusions from gallium nitride into gallium oxide materials.

Wherein the oxygen plasma treatment is performed on the plurality of protrusions, including:

and placing the epitaxial wafer with the plurality of protrusions into plasma processing equipment, introducing ozone into the plasma processing equipment, controlling the temperature in the plasma processing equipment to be 300-600 ℃ and the radio frequency power to be 15-50W, and performing oxygen plasma processing on the surface of the P-type gallium nitride layer for 30-500 s to bond the gallium nitride material with the oxygen to form a gallium oxide material.

Illustratively, the flow rate of the ozone introduced into the plasma treatment equipment is 5-500 ml.

Optionally, the height of each protrusion is 5-10 nm.

Step 308, a composite P-type layer is formed on the active layer.

The composite P-type layer comprises a first composite layer and a second composite layer which are sequentially stacked on the active layer, the first composite layer is a gallium nitride layer, and the second composite layer is a P-type gallium nitride layer. The plurality of protrusions penetrate through the first composite layer and are located in the second composite layer.

Optionally, the thickness of the first composite layer is 3-8 nm.

Optionally, the second composite layer includes a first sub-layer and a second sub-layer sequentially stacked on the first composite layer, a doping concentration of Mg in the first sub-layer is greater than a doping concentration of Mg in the second sub-layer, the thickness of the first sub-layer is 2-5 nm, and the thickness of the second sub-layer is 5-50 nm.

Optionally, the doping concentration of Mg in the first sublayer is 1 x 1020cm-3~4*1020cm-3The doping concentration of Mg in the second sublayer is 1 x 1019cm-3~6*1019cm-3

Illustratively, step 308 may include:

the first step, growing a first composite layer on an active layer;

wherein the growth temperature of the first composite layer is 800-1000 ℃, and the growth pressure is 200-500 torr.

And growing a first sub-layer on the first composite layer.

Wherein the thickness of the first sub-layer is 2-5 nm, the growth temperature of the first sub-layer is 800-900 ℃, and the growth pressure is 200-500 torr.

And thirdly, growing a second sublayer on the first sublayer.

Wherein the thickness of the second sub-layer is 5-50 nm. The growth temperature of the second sublayer is 800-1000 ℃, and the growth pressure is 200-500 torr.

Step 309, grow P-type contact layer on the composite P-type layer.

Wherein the P-type contact layer is a Mg-doped gallium nitride layer with the thickness of 10-25 nm and the doping concentration of Mg of 5 x 1019cm-3~1*1020cm-3. The growth temperature of the P-type contact layer is 700-900 ℃, and the growth pressure is 200-400 torr.

And after the epitaxial structure growth is finished, reducing the temperature of the reaction cavity, annealing in a nitrogen atmosphere, wherein the annealing temperature range is 650-850 ℃, annealing for 5-15 minutes, and finishing the epitaxial growth after the temperature is reduced to room temperature.

The embodiment of the disclosure realizes effective injection of carriers by arranging the composite P-type layer, wherein the composite P-type layer comprises a first composite layer and a second composite layer. The first composite layer is a gallium nitride layer, and the gallium nitride material is beneficial to the expansion and injection of holes. The second composite layer is a P-type gallium nitride layer which is a main hole providing layer and is used for providing holes. The active layer is provided with a plurality of bulges on the surface contacting with the first composite layer, and the bulges are made of gallium oxide materials, so that the band gap of the gallium oxide is wide, the planar expansion of a cavity is favorably realized, the lattice stress is released, and the crystal quality of the composite P-type layer is improved. And the plurality of bulges penetrate through the first composite layer and are positioned in the second composite layer, so that the plurality of bulges can be used as a plurality of transmission channels, partial holes provided by the second composite layer can be transmitted to the active layer through the plurality of channels, the hole transmission with different dimensionalities is regulated and controlled, and the hole injection efficiency is improved. And only the second composite layer in the composite P-type layer is doped with Mg, so that the doping of Mg in the P-type layer can be reduced, the expansion and effective injection of holes under low current are improved, and the luminous efficiency of the epitaxial wafer is improved.

The above description is intended to be exemplary only and not to limit the present disclosure, and any modification, equivalent replacement, or improvement made without departing from the spirit and scope of the present disclosure is to be considered as the same as the present disclosure.

12页详细技术资料下载
上一篇:一种医用注射器针头装配设备
下一篇:微型发光二极管及显示面板

网友询问留言

已有0条留言

还没有人留言评论。精彩留言会获得点赞!

精彩留言,会给你点赞!

技术分类