CN103681985B - Epitaxial wafer of a kind of light emitting diode and preparation method thereof - Google Patents

Abstract

The invention discloses an epitaxial wafer of a light-emitting diode and a manufacturing method thereof, belonging to the technical field of semiconductors. The epitaxial wafer includes a substrate, a low-temperature buffer layer grown on the substrate, a non-doped gallium nitride layer, an N-type gallium nitride layer, a multi-quantum well layer and a P-type gallium nitride layer. At least one quantum barrier layer from the side of the gallium layer is grown by Al _x Ga _1-x N, 0<x<0.3, and at least one quantum barrier layer from the side of the P-type gallium nitride layer is grown by In _z Ga _1-z N growth, 0<z<0.15, the P-type gallium nitride layer is directly grown on the multi-quantum well layer. In the present invention, the potential barrier of the quantum barrier layer close to the N-type GaN layer is relatively high, and the potential barrier of the quantum barrier layer close to the P-type GaN layer is relatively low, thereby reducing the overflow phenomenon of electrons and increasing the hole density. The high injection efficiency allows more electrons and holes to recombine into the quantum well layer, thereby improving the internal quantum efficiency of the light-emitting diode.

Description

A kind of epitaxial wafer of light-emitting diode and its manufacturing method

technical field

The invention relates to the technical field of semiconductors, in particular to an epitaxial wafer of a light emitting diode and a manufacturing method thereof.

Background technique

GaN (gallium nitride) is a typical representative of the third-generation wide-bandgap semiconductor materials. Its excellent high thermal conductivity, high temperature resistance, acid and alkali resistance, and high hardness make it widely used in the production of blue, green, and UV LEDs. GaN-based light emitting diodes generally include an epitaxial wafer and electrodes disposed on the epitaxial wafer.

An existing GaN-based semiconductor light-emitting epitaxial wafer, which includes a substrate, and an N-type layer, a multi-quantum well layer, an electron blocking layer, and a P-type layer grown sequentially on the substrate, wherein the structure of the multi-quantum well is InGaN/GaN, which confines the carriers, when the forward current passes, the electrons in the N-type layer and the holes in the P-type layer are confined to emit light in the quantum well layer. The electron blocking layer can reduce the overflow phenomenon of electrons, thereby improving the injection efficiency of carriers, and further improving the brightness of the light-emitting diode.

In the process of realizing the present invention, the inventor finds that there are at least the following problems in the prior art:

While blocking electron overflow, the electron blocking layer also blocks holes from being injected into the quantum well, so that the internal quantum efficiency of the light-emitting diode is still low, and the improvement of the brightness of the light-emitting diode is limited.

Contents of the invention

In order to solve the problems in the prior art, an embodiment of the present invention provides an epitaxial wafer of a light emitting diode and a manufacturing method thereof. Described technical scheme is as follows:

On the one hand, an embodiment of the present invention provides an epitaxial wafer of a light emitting diode, the epitaxial wafer includes a substrate, a low-temperature buffer layer grown on the substrate, a non-doped gallium nitride layer, an N-type nitride Gallium layer, multi-quantum well layer and P-type gallium nitride layer, the multi-quantum well layer is a superlattice structure, and the superlattice structure includes alternately grown quantum well layers and quantum barrier layers, from the N-type At least one quantum barrier layer starting from one side of the gallium nitride layer is grown by Al _x Ga _1-x N, 0<x<0.3, and at least one quantum barrier layer starting from the side of the P-type gallium nitride layer is grown by In _z Ga _1-z N growth, 0<z<0.15, the P-type gallium nitride layer is directly grown on the multiple quantum well layer.

Preferably, at least two quantum barrier layers starting from one side of the N-type gallium nitride layer are grown using Al _x Ga _1-x N, and at least two quantum barrier layers starting from the side of the N-type gallium nitride layer The Al component content in the layers is fixed or increases or decreases layer by layer.

Preferably, at least two quantum barrier layers starting from one side of the P-type gallium nitride layer are grown using In _z Ga _1-z N, and at least two quantum barrier layers starting from the side of the P-type gallium nitride layer The content of the In component in the layers is fixed or increases or decreases layer by layer.

Preferably, the barrier height of the middle quantum barrier layer of the multi-quantum well layer is greater than or equal to the barrier height of at least one quantum barrier layer starting from the side of the P-type gallium nitride layer, and the middle quantum The barrier height of the barrier layer is less than or equal to the barrier height of at least one quantum barrier layer starting from the side of the N-type gallium nitride layer, and the intermediate quantum barrier layer is, except for the N-type gallium nitride layer The at least one quantum barrier layer starting from one side of the gallium nitride layer and the quantum barrier layer other than the at least one quantum barrier layer starting from the side of the p-type gallium nitride layer.

Further, the intermediate quantum barrier layer is an AlxGa1 _{- xN} layer, an InzGa1 _{-zN layer} or a GaN layer.

Preferably, the thickness of each quantum well layer of the multiple quantum well layer is 2-3 nm, and the thickness of each quantum barrier layer is 10-20 nm.

Further, the thicknesses of the quantum barrier layers in the multiple quantum well layers are equal or unequal.

Preferably, the quantum well layer is an InGaN layer, and the composition content of In in the quantum barrier layer is smaller than the composition content of In in each quantum well layer.

Optionally, each quantum barrier layer in the multiple quantum well layer is doped with silicon.

On the other hand, an embodiment of the present invention provides a method for manufacturing an epitaxial wafer of a light emitting diode, the method comprising:

providing a substrate;

growing a low-temperature buffer layer, a non-doped gallium nitride layer, an n-type gallium nitride layer, a multi-quantum well layer and a p-type gallium nitride layer on the substrate, and the multi-quantum well layer is a superlattice structure , the superlattice structure includes alternately grown quantum well layers and quantum barrier layers, at least one quantum barrier layer starting from one side of the N-type gallium nitride layer is grown by Al _x Ga _1-x N, 0<x <0.3, at least one quantum barrier layer from one side of the P-type GaN layer is grown using In _z Ga _1-z N, 0<z<0.15, the P-type GaN layer is directly grown on the multiple quantum well layer.

The beneficial effects brought by the technical solution provided by the embodiments of the present invention are:

By growing at least one quantum barrier layer in the multi-quantum well layer close to the N-type gallium nitride layer using Al _x Ga _1-x N, the barrier height of the quantum barrier layer is increased, electrons are decelerated, and electron overflow is reduced . At least one quantum barrier layer in the multi-quantum well layer close to the P-type gallium nitride layer is grown with In _z Ga _1-z N, thereby reducing the blocking effect on holes and improving the injection efficiency of holes, and finally makes the More electrons and holes are confined in the quantum well to recombine and emit light, thereby improving the internal quantum efficiency of the LED.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

FIG. 1 is a schematic structural view of an epitaxial wafer of a light emitting diode provided in Embodiment 1 of the present invention;

Fig. 1 a is a partial energy band structure schematic diagram of a kind of multi-quantum well layer in the epitaxial wafer shown in Fig. 1;

Fig. 1 b is a partial energy band structure schematic diagram of another multi-quantum well layer in the epitaxial wafer shown in Fig. 1;

FIG. 2 is a schematic structural view of an epitaxial wafer of a light-emitting diode provided in Embodiment 2 of the present invention;

3 is a flow chart of a method for manufacturing an epitaxial wafer of a light-emitting diode provided in Embodiment 3 of the present invention;

Fig. 3a is a schematic diagram of a growth structure of a multi-quantum well layer provided in Embodiment 3.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Embodiment one

An embodiment of the present invention provides an epitaxial wafer of a light-emitting diode. Referring to FIG. Gallium nitride layer 4, multi-quantum well layer 5 and P-type gallium nitride layer 6, multi-quantum well layer 5 is a superlattice structure, and the superlattice structure includes quantum well layer 51 and quantum barrier layer 52 (see Figure 1a and 1b), quantum well layers 51 and quantum barrier layers 52 are grown alternately, wherein at least one quantum barrier layer 52a starting from the side of the N-type gallium nitride layer is grown by Al _x Ga _1-x N, 0<x<0.3 , at least one quantum barrier layer 52b starting from one side of the P-type gallium nitride layer is grown by In _z Ga _1-z N, 0<z<0.15, and the P-type gallium nitride layer 6 is directly grown on the multi-quantum well layer 5 superior.

Preferably, the number of periods of the multi-quantum well layer is 5-15, but it is not limited thereto and can be set according to actual needs. There are preferably two or three quantum barrier layers 52a, and one or two quantum barrier layers 52b.

Further, when there are at least two quantum barrier layers 52a (grown using AlxGa1 _{-xN )} , the Al component content in at least two quantum barrier layers 52a can be fixed or increased layer by layer or layer by layer decrease; when there are at least two quantum barrier layers 52b (grown using In _z Ga _1-z N), the In composition content in at least two quantum barrier layers 52b can be fixed or increased layer by layer or decreased layer by layer . Wherein, the content is fixed, that is, the values of x and Z do not change along the direction from the N-type gallium nitride layer 4 to the P-type gallium nitride layer 6; the content increases or decreases layer by layer, that is, along the direction from the N-type gallium nitride layer The values of the directions x and Z from the GaN layer 4 to the P-type GaN layer 6 increase or decrease layer by layer.

In this embodiment, the multi-quantum well layer 5 also includes an intermediate quantum barrier layer 52c, the potential barrier height of the intermediate quantum barrier layer 52c is greater than or equal to the potential barrier height of the quantum barrier layer 52b, and the potential barrier height of the intermediate quantum barrier layer 52c is less than Or equal to the barrier height of the quantum barrier layer 52a, the intermediate quantum barrier layer 52c is, except at least one quantum barrier layer 52a starting from the side of the N-type gallium nitride layer and at least one starting from the side of the P-type gallium nitride layer Quantum barrier layers other than the quantum barrier layer 52b. The potential barrier height of the quantum barrier layer 5a is relatively high, which can slow down the electrons and reduce the overflow of electrons, so that more electrons can be concentrated into the multiple quantum wells. The potential barrier height of the quantum barrier layer 52b is low, which can reduce the interference The resistance of holes is conducive to the injection of holes, and finally more electrons and holes can recombine and emit light in the quantum well.

Further, the intermediate quantum barrier layer 52c may be an AlxGa1 _{- xN} layer, an InzGa1 _{-zN layer} or a GaN layer.

Furthermore, the quantum well layer 51 is an InGaN layer, and the composition content of In in the quantum barrier layer 52b is smaller than that of In in each quantum well layer 51, to ensure that the forbidden band width of the quantum barrier layer is greater than that of the quantum well layer Bandwidth. It is easy to know that the quantum well layer 51 is grown by InGaN, but not limited to other doping.

As an example of this embodiment, referring to FIG. 1a, the multiple quantum well layer may include three quantum barrier layers 52a, three quantum barrier layers 52b and three quantum barrier layers 52c. The content of the Al component in the quantum barrier layer 52a and the content of the In component in the quantum barrier layer 52b are all fixed. As can be seen from FIG. The component contents are equal so the barrier height is the same; the barrier height of the quantum barrier layer 52b is the lowest, and the three quantum barrier layers 52b are also the same because the In component content is equal; the quantum barrier layer of the quantum barrier layer 52c The potential barrier height is smaller than the potential barrier height of the quantum barrier layer 52a, and the potential barrier height of the quantum barrier layer 52c is greater than the potential barrier height of the quantum barrier layer 52b.

As another example of this embodiment, referring to FIG. 1b, the multiple quantum well layer may include three quantum barrier layers 52a, three quantum barrier layers 52c and three quantum barrier layers 52b. In this structure, the content of the Al component in the quantum barrier layer 52a decreases layer by layer, and the content of the In component in the quantum barrier layer 52b increases layer by layer. It can be seen from FIG. 1b that the barrier height of the quantum barrier layer 52a is the highest. And the three quantum barrier layers 52a also gradually reduce the barrier height because the Al component content decreases layer by layer; the potential barrier height of the quantum barrier layer 52b is the lowest, and the In component content in the three quantum barrier layers 52b increases layer by layer, so The barrier height gradually decreases; the barrier height of the quantum barrier layer 52c is smaller than that of the quantum barrier layer 52a, and the barrier height of the quantum barrier layer 52c is greater than that of the quantum barrier layer 52b.

It is easy to know that under the premise that the barrier height of the quantum barrier layer 52c is greater than or equal to the barrier height of the quantum barrier layer 52b, and the barrier height of the quantum barrier layer 52c is less than or equal to the barrier height of the quantum barrier layer 52a, the above-mentioned For example, the content of the Al component in the quantum barrier layer 52a is fixed, and the content of the In component in the quantum barrier layer 52b increases layer by layer; or, the content of the Al component in the quantum barrier layer 52a decreases layer by layer, and the content of the In component in the quantum barrier layer 52b The content of the In component is fixed; or, the content of the Al component in the quantum barrier layer 52a increases layer by layer, and the content of the In component in the quantum barrier layer 52b decreases layer by layer; or, the content of the Al component in the quantum barrier layer 52a is fixed and the quantum The content of the In component in the barrier layer 52b decreases layer by layer; or, the content of the Al component in the quantum barrier layer 52a increases layer by layer, and the content of the In component in the quantum barrier layer 52b is fixed.

Wherein, preferably, the content of the Al component in the quantum barrier layer 52a decreases layer by layer, and the content of the In component in the quantum barrier layer 52b increases layer by layer. In this structure, as the content of the Al component in the quantum barrier layer 52a changes from more to less, the barrier height of the multi-quantum barrier layer gradually decreases along the direction from the N-type gallium nitride layer to the P-type gallium nitride layer, which is beneficial to The electrons that migrate from the N gallium nitride type direction to the quantum well layer are decelerated to reduce the overflow; the In in the quantum barrier layer 52b changes from less to more, and the barrier height of the multi-quantum barrier layer is along the direction from the P-type gallium nitride layer. Gradually rising toward the N-type GaN layer is beneficial to reduce the resistance of holes migrating from the P-type GaN layer to the quantum well.

Preferably, the thickness of each quantum well layer of the multi-quantum well layer 5 is 2-3 nm, and the thickness of each quantum barrier layer is 10-20 nm. Because the In of the quantum well layer 51 formed by InGaN growth is easy to diffuse, if the quantum barrier layer 52 is thinner, the diffusion of In of the InGaN quantum well layer 51 cannot be blocked well, and may cause the InGaN quantum well layer 51. Coupling; the thickness of quantum barrier layer 52 is too thick, and hole is difficult for entering in the InGaN quantum well layer 51, therefore, limit the thickness of quantum barrier layer 52, can guarantee that hole is easy while blocking the In diffusion of quantum well layer 51. into the quantum well layer 51. In addition, the thickness setting of the quantum barrier layer 52 will also affect the migration of electrons and holes and crystal quality. For example, when the quantum barrier layer is thickened, although the crystal quality can be improved, it will also increase the blocking effect on electrons and holes, especially the blocking of holes, which will make there are not enough electrons and holes in the quantum well layer. If the quantum barrier layer is thinned, the quality of the crystal will be poor, resulting in poor antistatic energy. Therefore, the thickness of the quantum barrier layer needs to be controlled within an appropriate range.

Further, the thicknesses of the quantum barrier layers in the multiple quantum well layer 5 may be equal or unequal. Each quantum barrier layer in the multi-quantum well layer 5 can be doped with Si (silicon), and the multi-quantum well layer doped with Si is beneficial to reduce the resistance of the light emitting diode.

Optionally, the substrate 1 includes but not limited to a sapphire substrate.

Optionally, the low-temperature buffer layer 2 may be made of materials such as gallium nitride, aluminum nitride, or aluminum gallium nitride.

Optionally, the multi-quantum well layer 5 can be directly grown on the N-type gallium nitride layer 4 , or the multi-quantum well layer 5 can be grown after inserting other buffer layers or stress release layers. In this embodiment, the N-type GaN layer 4 may be a Si-doped GaN layer, but not limited to Si-doped, and the N-type GaN layer may be a single layer or a multi-layer.

Optionally, the P-type gallium nitride layer 6 uses Mg (magnesium) doped GaN as the growth material. It is easy to know that the P-type gallium nitride layer 6 in this embodiment is not limited to Mg doping, and the P-type gallium nitride layer 6 can be a single layer or multiple layers.

Optionally, the epitaxial wafer structure may also include a P-type contact layer 7 grown on the P-type GaN layer 6 .

The beneficial effects brought by the technical solution provided by the embodiments of the present invention are:

By growing at least one quantum barrier layer in the multi-quantum well layer close to the N-type gallium nitride layer using Al _x Ga _1-x N, the barrier height of the quantum barrier layer is increased, electrons are decelerated, and electron overflow is reduced . At least one quantum barrier layer in the multi-quantum well layer close to the P-type gallium nitride layer is grown with In _z Ga _1-z N, thereby reducing the blocking effect on holes and improving the injection efficiency of holes, and finally makes the More electrons and holes are confined in the quantum well to recombine and emit light, thereby improving the internal quantum efficiency of the LED.

Embodiment two

An embodiment of the present invention provides an epitaxial wafer of a light-emitting diode. The structure of the epitaxial wafer in this embodiment is basically the same as that of the epitaxial wafer in Embodiment 1. The difference is that the multi-quantum well layer 5 of the epitaxial wafer does not include The middle quantum barrier layer 52c.

Referring to FIG. 2, the epitaxial wafer includes a substrate 1, a low-temperature buffer layer 2, an undoped gallium nitride layer 3, an N-type gallium nitride layer 4, a multi-quantum well layer 5, and a P-type gallium nitride layer from bottom to top. Layer 6, multi-quantum well layer 5 is a superlattice structure, each period includes quantum well layer 51 and quantum barrier layer 52, quantum well layer 51 and quantum barrier layer 52 grow alternately, wherein, from N-type gallium nitride layer- At least one quantum barrier layer 52a starting from the P-type gallium nitride layer is grown using Al _x Ga _1-x N, 0<x<0.3, and at least one quantum barrier layer 52b starting from the side of the P-type gallium nitride layer is grown using In _z Ga _1-z N growth, 0<z<0.15, and the P-type gallium nitride layer 6 is directly grown on the multi-quantum well layer 5 .

Except that the epitaxial wafer in this embodiment does not include the intermediate quantum barrier layer 52c, other structures and characteristics are the same as those in Embodiment 1, and will not be repeated here.

The beneficial effects brought by the technical solution provided by the embodiments of the present invention are:

By growing at least one quantum barrier layer in the multi-quantum well layer close to the N-type gallium nitride layer using AlxGa1 _{-xN ,} the potential barrier height of the quantum barrier layer is increased, electrons are decelerated, and electron overflow is reduced. At least one quantum barrier layer in the multi-quantum well layer close to the P-type gallium nitride layer is grown with In _z Ga _1-z N, thereby reducing the blocking effect on holes and improving the injection efficiency of holes, and finally makes the More electrons and holes are confined in the quantum well to recombine and emit light, thereby improving the internal quantum efficiency of the LED.

Embodiment three

An embodiment of the present invention provides a method for manufacturing an epitaxial wafer of a light-emitting diode. Referring to FIG. 3 , the method includes:

Step 301: providing a substrate;

Optionally, in this embodiment, the substrate includes but not limited to a sapphire substrate.

At the time of implementation, the substrate can be heat-treated at 1300 °C for 10 minutes under _H2 atmosphere to clean the surface.

Step 302: growing a low-temperature buffer layer, a non-doped gallium nitride layer, and an N-type gallium nitride layer sequentially on the substrate;

Optionally, in this embodiment, the low-temperature buffer layer may be a gallium nitride layer, or may be an aluminum nitride layer or an aluminum gallium nitride layer. Specifically, at a temperature of 550° C., a low-temperature buffer layer made of GaN is grown on the surface of the substrate with a thickness of 20-30 nm.

Specifically, growing the non-doped gallium nitride layer may be to raise the temperature to 1100° C., and grow a non-doped GaN layer with a thickness of 3 μm on the low-temperature buffer layer, that is, the high-temperature buffer layer.

Optionally, the multi-quantum well layer can be directly grown on the N-type gallium nitride layer, or the multi-quantum well layer can be grown after inserting other buffer layers or stress release layers. In this embodiment, the N-type GaN layer may be a silicon-doped GaN layer, but not limited to Si-doped, and the N-type GaN layer may be a single layer or a multi-layer. Specifically, a layer of Si-doped GaN with a thickness of 2 μm is grown on the buffer layer. It is easy to know that the N-type GaN layer is not limited to Si doping.

Step 303: growing a multi-quantum well layer on the N-type gallium nitride layer, the multi-quantum well layer is a superlattice structure, and the superlattice structure includes alternately grown quantum well layers and quantum barrier layers;

Among them, at least one quantum barrier layer starting from the side of the N-type gallium nitride layer is grown by Al _x Ga _1-x N, 0<x<0.3, and at least one quantum barrier layer starting from the side of the P-type gallium nitride layer The layer is grown by In _z Ga _1-z N, 0<z<0.15, and the P-type gallium nitride layer is directly grown on the uppermost quantum barrier layer of the multiple quantum well layer.

Preferably, the number of periods of the multi-quantum well layer is 5-15, but it is not limited thereto and can be set according to actual needs. There are preferably two or three quantum barrier layers starting from the side of the N-type gallium nitride layer, and preferably one or two quantum barrier layers starting from the side of the P-type gallium nitride layer.

Further, when there are at least two quantum barrier layers (grown by Al _x Ga _1-x N) starting from one side of the N-type gallium nitride layer, the Al component content in at least two quantum barrier layers can be fixed or Increase layer by layer or decrease layer by layer; when there are at least two quantum barrier layers (grown with In _z Ga _1-z N) from the side of the P-type gallium nitride layer, the In in at least two quantum barrier layers The component content can be fixed or increased or decreased layer by layer. Among them, the content is fixed, that is, the values of x and Z do not change along the direction from the N-type GaN layer to the P-type GaN layer; the content increases or decreases layer by layer, that is, along the direction from the N-type GaN layer The values of x and Z in the direction from the layer to the P-type gallium nitride layer gradually increase or decrease gradually.

Among them, it is preferable that the Al component content in at least one quantum barrier layer starting from the side of the N-type gallium nitride layer decreases layer by layer, and the content of the In composition in the at least one quantum barrier layer starting from the side of the P-type gallium nitride layer The component content increases layer by layer. In this structure, as the content of the Al component changes from more to less, the barrier height of the multi-quantum barrier layer gradually decreases along the direction from the N-type gallium nitride layer to the P-type gallium nitride layer, which is conducive to making the transition from N-type GaN layer to P-type GaN layer. The electrons migrating to the quantum well layer in the direction of gallium decelerate, reducing overflow; the In in the quantum barrier layer of the second quantum well layer changes from less to more, and the barrier height of the multi-quantum barrier layer increases from the P-type gallium nitride layer Gradually rising toward the N-type GaN layer is beneficial to reduce the resistance of holes migrating from the P-type GaN layer to the quantum well.

Furthermore, the quantum well layer is an InGaN layer, and the composition content of In in the quantum barrier layer is smaller than that of In in each quantum well layer, so as to ensure that the forbidden band width of the quantum barrier layer is greater than that of the quantum well layer width. It is easy to know that the quantum well layer is grown by InGaN, but not limited to other doping.

In this implementation, the multi-quantum well layer 5 of the epitaxial wafer also includes an intermediate quantum barrier layer, that is, in addition to at least one quantum barrier layer starting from the side of the N-type gallium nitride layer and starting from the side of the P-type gallium nitride layer at least one quantum barrier layer other than the quantum barrier layer.

In this embodiment, the barrier height of the intermediate quantum barrier layer is less than or equal to the barrier height of at least one quantum barrier layer starting from the side of the N-type gallium nitride layer, and greater than or equal to the barrier height of at least one quantum barrier layer starting from the side of the P-type gallium nitride layer. The initial barrier height of at least one quantum barrier layer. The barrier height of at least one quantum barrier layer starting from the side of the N-type gallium nitride layer is relatively high, which can slow down the electrons and reduce the overflow of electrons, so that more electrons can be concentrated in the multiple quantum wells. From the P-type The barrier height of at least one quantum barrier layer starting from one side of the gallium nitride layer is lower, which can reduce the resistance to holes, facilitate the injection of holes, and finally make more electrons and holes in the quantum well Composite glow.

Further, the growth of the intermediate quantum barrier layer may be a GaN layer, an In _z Ga _1-z N layer or an Al _x Ga _1-x N layer.

In other embodiments, the multiple quantum well layer 5 of the epitaxial wafer may not include an intermediate quantum barrier layer.

Preferably, the thickness of each quantum well layer of the multi-quantum well layer is 2-3 nm, and the thickness of each quantum barrier layer is 10-20 nm. Because the In of the quantum well layer can diffuse, if the quantum barrier layer is thinner, the diffusion of the In of the quantum well layer cannot be blocked well, and may cause the coupling between the quantum well layers; the thickness of the quantum barrier layer is too thick, and the hole It is not easy to enter the quantum well layer. Therefore, the thickness of the quantum barrier layer is limited to prevent the In diffusion of the InGaN quantum well layer and ensure that holes can easily enter the quantum well layer. In addition, the thickness setting of the quantum barrier layer 52 will also affect the migration of electrons and holes and crystal quality. For example, when the quantum barrier layer is thickened, although the crystal quality can be improved, it will also increase the blocking effect on electrons and holes, especially the blocking of holes, which will make there are not enough electrons and holes in the quantum well layer. If the quantum barrier layer is thinned, the quality of the crystal will be poor, resulting in poor antistatic energy. Therefore, the thickness of the quantum barrier layer needs to be controlled within an appropriate range.

Further, the thicknesses of the quantum barrier layers in the multiple quantum well layers may be equal or unequal. Each quantum barrier layer in a multiple quantum well layer includes, but is not limited to, Si doping. Doping Si is beneficial to reduce the resistance of light-emitting diodes.

3a, for example, first grow four multi-quantum well layers on the N-type gallium nitride layer, that is, alternately grow four quantum well layers 51 and quantum barrier layers 52a, and then grow two multi-quantum well layers, that is, alternately grow two quantum well layers. A quantum well layer 51 and a quantum barrier layer 52c, and then grow two multi-quantum well layers, that is, alternately grow two quantum well layers 51 and quantum barrier layers 52b, and then form a multi-quantum well layer. Wherein, the quantum well layers are all grown by InGaN, and the composition of In in each quantum well layer is the same. The quantum barrier layer 52a is grown by AlGaN, wherein the Al components are 25%, 20%, 15% and 10% respectively. The quantum barrier layer 52c is grown by GaN, and the quantum barrier layer 52b is grown by InGaN, wherein the components of In are 5% and 10% respectively. The thickness of each quantum well layer is 2.5nm, and the thickness of each quantum barrier layer can be 2-3nm.

It should be noted that the number of quantum well layers and quantum barrier layers in the multi-quantum well layer in this example is only an example of this embodiment, and is not intended to limit the present invention.

Step 304: growing a P-type gallium nitride layer on the last quantum barrier layer of the multi-quantum well layer;

Optionally, the P-type gallium nitride layer uses Mg (magnesium) doped GaN as the growth material. It is easy to know that the P-type gallium nitride layer in this embodiment is not limited to Mg doping, and other doping can also be used. The GaN-type GaN layer can be a single layer or a multi-layer. Specifically, P-type Mg-doped GaN is grown on the last quantum barrier layer of the multi-quantum well layer, and its thickness is about 300 nm.

In this embodiment, the method further includes step 305: growing a P-type contact layer on the P-type GaN layer.

It should be noted that in specific implementation, the embodiment of the present invention can use high-purity _H2 or _N2 as the carrier gas, and use TMGa, TMAl, TMIn and _NH3 as Ga source, Al source, In source and N source respectively, Use SiH ₄ and Cp ₂ Mg as N-type and P-type dopants respectively, and use metal-organic chemical vapor deposition equipment or other equipment to complete epitaxial wafer growth.

The beneficial effects brought by the technical solution provided by the embodiments of the present invention are:

By growing at least one quantum barrier layer in the multi-quantum well layer close to the N-type gallium nitride layer using AlxGa1 _{-xN ,} the potential barrier height of the quantum barrier layer is increased, electrons are decelerated, and electron overflow is reduced. At least one quantum barrier layer in the multi-quantum well layer close to the P-type gallium nitride layer is grown with In _z Ga _1-z N, thereby reducing the blocking effect on holes and improving the injection efficiency of holes, and finally making the More electrons and holes are confined in the quantum well to recombine and emit light, thereby improving the internal quantum efficiency of the LED.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (10)

1. an epitaxial wafer for light emitting diode, described epitaxial wafer comprises substrate, is grown on described substrateGallium nitride layer, n type gallium nitride layer, multiple quantum well layer and the P type gallium nitride layer of low temperature buffer layer, non-doping,Described multiple quantum well layer is superlattice structure, and described superlattice structure comprises quantum well layer and the amount of alternating growthSon is built layer, it is characterized in that,

At least one quantum barrier layer starting from described n type gallium nitride layer one side adopts Al_xGa_1-xN growth,0 < x < 0.3, at least one quantum barrier layer starting from described P type gallium nitride layer one side adopts In_zGa_1-zN growth,0 < z < 0.15, described P type gallium nitride layer is grown directly upon on described multiple quantum well layer.

2. epitaxial wafer according to claim 1, is characterized in that, from described n type gallium nitride layer one sideAt least two quantum barrier layers that start adopt Al_xGa_1-xN growth, starts from described n type gallium nitride layer one sideAl constituent content at least two quantum barrier layers immobilizes or successively raises or successively reduce.

3. epitaxial wafer according to claim 1, is characterized in that, from described P type gallium nitride layer one sideAt least two quantum barrier layers that start adopt In_zGa_1-zN growth, starts from described P type gallium nitride layer one sideIn constituent content at least two quantum barrier layers immobilizes or successively raises or successively reduce.

4. epitaxial wafer according to claim 1, is characterized in that, the intermediate quantity of described multiple quantum well layerThe barrier height that son is built layer is more than or equal to described at least one amount starting from described P type gallium nitride layer one sideSon is built the barrier height of layer, and the barrier height of described middle quantum barrier layer is less than or equal to described from described N-typeThe barrier height of at least one quantum barrier layer that gallium nitride layer one side starts, described middle quantum barrier layer is to removeDescribed at least one quantum barrier layer starting from described n type gallium nitride layer one side and described from described P type nitrogenQuantum barrier layer beyond at least one quantum barrier layer that change gallium layer one side starts.

5. epitaxial wafer according to claim 4, is characterized in that, described middle quantum barrier layer isAl_xGa_1-xN layer, In_zGa_1-zN layer or GaN layer.

6. epitaxial wafer according to claim 1, is characterized in that, each quantum of described multiple quantum well layerThe thickness of trap layer is respectively 2～3nm, and the thickness of each quantum barrier layer is respectively 10～20nm.

7. epitaxial wafer according to claim 1, is characterized in that, the each amount in described multiple quantum well layerThe thickness that son is built layer is equal or unequal.

8. epitaxial wafer according to claim 1, is characterized in that, described quantum well layer is InGaN layer,And in described quantum barrier layer, the constituent content of In is less than the constituent content of In in each quantum well layer.

9. epitaxial wafer according to claim 1, is characterized in that, the each amount in described multiple quantum well layerSon is built layer silicon doping.

10. a preparation method for the epitaxial wafer of light emitting diode, described method comprises:

One substrate is provided;

In gallium nitride layer, n type gallium nitride layer, the volume of described Grown low temperature buffer layer, non-dopingSub-trap layer and P type gallium nitride layer, described multiple quantum well layer is superlattice structure, described superlattice structure comprisesThe quantum well layer of alternating growth and quantum barrier layer, is characterized in that,

At least one quantum barrier layer starting from described n type gallium nitride layer one side adopts Al_xGa_1-xN growth,0 < x < 0.3, at least one quantum barrier layer starting from described P type gallium nitride layer one side adopts In_zGa_1-zN growth,0 < z < 0.15, described P type gallium nitride layer is grown directly upon on described multiple quantum well layer.