Light-emitting diode epitaxial wafer and preparation method thereof

Abstract

The present invention relates to the field of semiconductor technology, and specifically discloses a light-emitting diode epitaxial wafer and a preparation method thereof. The epitaxial wafer comprises a substrate and an epitaxial layer, the epitaxial layer comprises an active layer, an electron blocking layer and a P-type layer, a hole injection layer is provided between the active layer and the electron blocking layer, the hole injection layer comprises a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer sequentially deposited along the epitaxial direction, the first superlattice layer is a periodic structure of alternately stacked unintentionally Mg-doped AlGaN layers and low-Mg-doped AlGaN layers, the second superlattice layer is a periodic structure of alternately stacked unintentionally Mg-doped GaN layers and high-Mg-doped InGaN layers, the Mg doping concentration of the high-Mg-doped InGaN layer is greater than the Mg doping concentration of the magnesium-carbon co-doped GaN composite layer, and the Mg doping concentration of the magnesium-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low-Mg-doped AlGaN layer. The present invention effectively reduces the self-compensation effect of Mg through the mutual cooperation of multiple material layers, increases the activated Mg concentration, increases the hole concentration, increases the effective hole injection efficiency, reduces electron overflow, thereby increasing the radiation recombination efficiency of electrons and holes in the active layer, and further improving the luminous efficiency of the light-emitting diode.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a light emitting diode epitaxial wafer and a preparation method thereof. Background Art

[0002] In the existing technology, p-type GaN has a very low carrier concentration due to the passivation and self-compensation effects of the acceptor, which also seriously restricts the application and development of GaN materials. So far, in industrial production or laboratory research, the dopants with high doping efficiency used in the growth of p-type GaN using the MOCVD method are almost all Mg (i.e. Cp2Mg, dicyclopentadienyl magnesium). Among them, Mg atoms enter the GaN lattice, and most of the Mg atoms will exist in the form of replacing Ga atoms, and only a few Mg atoms will exist in the form of interstitial atoms in the lattice gap of GaN. Since the outermost layer of Mg atoms has one less electron than the outermost layer of Ga atoms, the Mg atoms will form a negative charge center and become acceptors. However, on the one hand, the energy level of the Mg acceptor is relatively deep, about 170meV, and the ionization rate of Mg at room temperature is only about 1%; on the other hand, the mobility of electrons in the GaN material system is much greater than the mobility of holes, and the active region's ability to confine electrons is weakened. Some electrons can pass through the active region from the n-type side to the p-type side, causing electron leakage. The matching degree between electrons and holes in the active region decreases, resulting in a decrease in the efficiency of the LED device. Summary of the Invention

[0003] The purpose of the present invention is to provide a light emitting diode epitaxial wafer and a preparation method thereof in view of the existing technical status.

[0004] The present invention effectively reduces the self-compensation effect of Mg through the mutual cooperation of multiple material layers, increases the activated Mg concentration, increases the hole concentration, increases the effective hole injection efficiency, reduces electron overflow, thereby increasing the radiation recombination efficiency of electrons and holes in the active layer, and further improving the luminous efficiency of the light-emitting diode.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] First, the present invention provides a light-emitting diode epitaxial wafer, comprising a substrate and an epitaxial layer disposed on the substrate, wherein the epitaxial layer comprises a buffer layer, an undoped GaN layer, an N-type layer, an active layer, an electron blocking layer, and a P-type layer sequentially deposited on the substrate along an epitaxial direction.

[0007] A hole injection layer is provided between the active layer and the electron blocking layer, and the hole injection layer comprises a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer sequentially deposited along the epitaxial direction.

[0008] The first superlattice layer is a periodic structure of an AlGaN layer not intentionally doped with Mg and an AlGaN layer with low Mg doping alternately stacked.

[0009] The second superlattice layer is a periodic structure composed of GaN layers not intentionally doped with Mg and InGaN layers highly doped with Mg alternately stacked.

[0010] The Mg doping concentration of the high Mg-doped InGaN layer is greater than the Mg doping concentration of the Mg-carbon co-doped GaN composite layer, and the Mg doping concentration of the Mg-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0011] In some embodiments, the Mg doping concentration in the low Mg-doped AlGaN layer is 1×10 17 cm -3 ~1×10 18 cm -3 The Mg doping concentration of the highly Mg-doped InGaN layer is 1×10 20 cm -3 ~1×10 21 cm -3 .

[0012] In some embodiments, the magnesium-carbon co-doped GaN composite layer includes a first magnesium-carbon co-doped GaN layer, a second magnesium-carbon co-doped GaN layer, and a third magnesium-carbon co-doped GaN layer sequentially deposited on the first superlattice layer along the epitaxial direction.

[0013] The Mg doping concentration of the highly Mg-doped InGaN layer is greater than the Mg doping concentration of the second Mg-carbon co-doped GaN layer, the Mg doping concentration of the second Mg-carbon co-doped GaN layer is greater than the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer, and the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer are both greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0014] In some embodiments, the Mg doping concentration of the first MgC co-doped GaN layer and the Mg doping concentration of the third MgC co-doped GaN layer are both 1×10 18 cm -3 ~1×10 19 cm -3 The Mg doping concentration of the second MgC co-doped GaN layer is 1×10 19 cm -3 ~1×10 20 cm -3 .

[0015] In some embodiments, the carbon doping concentration of the first magnesium-carbon co-doped GaN layer, the second magnesium-carbon co-doped GaN layer, and the third magnesium-carbon co-doped GaN layer is 1×10 17 cm -3 ~8×10 17 cm -3 .

[0016] In some embodiments, the first MgC co-doped GaN layer, the second MgC co-doped GaN layer, and the third MgC co-doped GaN layer are all provided with V-shaped pits, and in the second superlattice layer, the non-intentionally Mg-doped GaN layer closest to the third MgC co-doped GaN layer fills and merges the V-shaped pits on the third MgC co-doped GaN layer.

[0017] In some embodiments, the number of periods of the first superlattice layer is 1 to 10, the thickness ratio a of the low Mg-doped AlGaN layer / the unintentionally Mg-doped AlGaN layer is 1≤a≤2, and the proportion of Al components in the unintentionally Mg-doped AlGaN layer and the low Mg-doped AlGaN layer is 0.01 to 0.1.

[0018] In some embodiments, the number of periods of the second superlattice layer is 1 to 30, the thickness ratio b of the highly Mg-doped InGaN layer / the non-intentionally Mg-doped GaN layer is 1≤b≤2, and the proportion of In component in the highly Mg-doped InGaN layer is 0.01 to 0.1.

[0019] Secondly, the present invention also provides a method for preparing a light-emitting diode epitaxial wafer, comprising:

[0020] providing a substrate,

[0021] depositing an epitaxial layer on the substrate,

[0022] The epitaxial layer includes a buffer layer, an undoped GaN layer, an N-type layer, an active layer, an electron blocking layer and a P-type layer sequentially deposited on the substrate along the epitaxial direction.

[0023] A hole injection layer is provided between the active layer and the electron blocking layer, and the hole injection layer comprises a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer sequentially deposited along the epitaxial direction.

[0024] The first superlattice layer is a periodic structure of an AlGaN layer not intentionally doped with Mg and an AlGaN layer with low Mg doping alternately stacked.

[0025] The second superlattice layer is a periodic structure composed of GaN layers not intentionally doped with Mg and InGaN layers highly doped with Mg alternately stacked.

[0026] The Mg doping concentration of the high Mg-doped InGaN layer is greater than the Mg doping concentration of the Mg-carbon co-doped GaN composite layer, and the Mg doping concentration of the Mg-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0027] In some embodiments, the magnesium-carbon co-doped GaN composite layer includes a first magnesium-carbon co-doped GaN layer, a second magnesium-carbon co-doped GaN layer, and a third magnesium-carbon co-doped GaN layer sequentially deposited on the first superlattice layer along the epitaxial direction.

[0028] The Mg doping concentration of the highly Mg-doped InGaN layer is greater than the Mg doping concentration of the second Mg-carbon co-doped GaN layer, the Mg doping concentration of the second Mg-carbon co-doped GaN layer is greater than the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer, and the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer are both greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0029] The beneficial effects of the present invention are:

[0030] In the present invention, a hole injection layer consisting of a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer is provided between the active layer and the electron blocking layer, wherein:

[0031] First, the first superlattice layer is a periodic structure composed of alternating layers of unintentionally Mg-doped AlGaN layers and low-Mg-doped AlGaN layers. Through the alternating stacking of the two materials, on the one hand, holes in the low-Mg-doped AlGaN layer can diffuse into the unintentionally Mg-doped AlGaN layer where ionized impurity scattering is weaker. Compared with the structural setting of a single low-Mg-doped AlGaN material layer, this alternating stacking structure has a higher effective hole mobility. At the same time, the Mg doping concentration of the low-Mg-doped AlGaN layer is low, which can reduce the self-compensation effect of Mg. On the other hand, this alternating stacking structure can optimize the band structure and is located close to the active layer, which can effectively reduce electron overflow.

[0032] Secondly, a magnesium-carbon co-doped GaN composite layer is deposited on the first superlattice layer, and the Mg doping concentration of the magnesium-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low-Mg-doped AlGaN layer, that is, the magnesium-carbon co-doped GaN composite layer increases the Mg doping concentration and introduces C. On the one hand, the increase in the Mg doping concentration can increase the concentration of holes diffused into the active layer. At the same time, the complex formed by C in the material layer exhibits acceptor properties, assists in replenishing holes, further increases the hole concentration, and reduces the formation of non-ideal complexes of Mg in the material layer (exhibiting donor properties), thereby reducing the number of self-compensation centers and effectively reducing the self-compensation effect of Mg. At the same time, it reduces the electron overflow problem caused by local energy band bending and changes in electric field distribution due to the memory effect of Mg, effectively reducing electron overflow.

[0033] Furthermore, after the epitaxial layer is improved by the first superlattice layer and the magnesium-carbon co-doped GaN composite layer, a second superlattice layer is deposited on the magnesium-carbon co-doped GaN composite layer. The second superlattice layer is a periodic structure of alternating GaN layers not intentionally doped with Mg and InGaN layers with high Mg doping, and the Mg doping concentration of the high Mg doping InGaN layer is greater than the Mg doping concentration of the magnesium-carbon co-doped GaN composite layer. The material layer containing the high Mg doping concentration is placed on the side of the hole injection layer away from the active layer, which not only ensures the crystal quality of the second superlattice layer when highly doped with Mg, but also increases the activated Mg concentration. In addition, the energy level of the Mg acceptor is deeper (about 170meV), and In atoms can reduce the activation energy of Mg and increase the activated Mg concentration.

[0034] Therefore, the present invention effectively reduces the self-compensation effect of Mg, increases the activated Mg concentration, increases the hole concentration, increases the effective hole injection efficiency, reduces electron overflow, and thus increases the radiation recombination efficiency of electrons and holes in the active layer, thereby improving the luminous efficiency of the light-emitting diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The figure is a structural schematic diagram of a light emitting diode epitaxial wafer of the present invention.

[0036] Figure 2 Schematic diagram of the structure of the hole injection layer of the present invention. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

[0038] First, see Figure 1As shown, the present invention provides a light-emitting diode epitaxial wafer, comprising a substrate 1 and an epitaxial layer provided on the substrate, wherein the epitaxial layer comprises a buffer layer 2, an undoped GaN layer 3, an N-type layer 4, an active layer 5, an electron blocking layer 7 and a P-type layer 8 sequentially deposited on the substrate along an epitaxial direction.

[0039] A hole injection layer 6 is provided between the active layer and the electron blocking layer. The hole injection layer comprises a first superlattice layer 61, a magnesium-carbon co-doped GaN composite layer 62 and a second superlattice layer 63 sequentially deposited along the epitaxial direction.

[0040] The first superlattice layer is a periodic structure of an AlGaN layer 611 not intentionally doped with Mg and an AlGaN layer 612 with low Mg doping, alternately stacked.

[0041] The second superlattice layer is a periodic structure composed of GaN layers 631 not intentionally doped with Mg and InGaN layers 632 highly doped with Mg alternately stacked.

[0042] The Mg doping concentration of the high Mg-doped InGaN layer is greater than the Mg doping concentration of the Mg-carbon co-doped GaN composite layer, and the Mg doping concentration of the Mg-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0043] In the present invention, a hole injection layer consisting of a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer is provided between the active layer and the electron blocking layer, wherein:

[0044] First, the first superlattice layer is a periodic structure composed of alternating layers of unintentionally Mg-doped AlGaN layers and low-Mg-doped AlGaN layers. Through the alternating stacking of the two materials, on the one hand, holes in the low-Mg-doped AlGaN layer can diffuse into the unintentionally Mg-doped AlGaN layer where ionized impurity scattering is weaker. Compared with the structural setting of a single low-Mg-doped AlGaN material layer, this alternating stacking structure has a higher effective hole mobility. At the same time, the Mg doping concentration of the low-Mg-doped AlGaN layer is low, which can reduce the self-compensation effect of Mg. On the other hand, this alternating stacking structure can optimize the band structure and is located close to the active layer, which can effectively reduce electron overflow.

[0045] Secondly, a magnesium-carbon co-doped GaN composite layer is deposited on the first superlattice layer, and the Mg doping concentration of the magnesium-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low-Mg-doped AlGaN layer, that is, the magnesium-carbon co-doped GaN composite layer increases the Mg doping concentration and introduces C. On the one hand, the increase in the Mg doping concentration can increase the concentration of holes diffused into the active layer. At the same time, the complex formed by C in the material layer exhibits acceptor properties, assists in replenishing holes, further increases the hole concentration, and reduces the formation of non-ideal complexes of Mg in the material layer (exhibiting donor properties), thereby reducing the number of self-compensation centers and effectively reducing the self-compensation effect of Mg. At the same time, it reduces the electron overflow problem caused by local energy band bending and changes in electric field distribution due to the memory effect of Mg, effectively reducing electron overflow.

[0046] Furthermore, after the epitaxial layer is improved by the first superlattice layer and the magnesium-carbon co-doped GaN composite layer, a second superlattice layer is deposited on the magnesium-carbon co-doped GaN composite layer. The second superlattice layer is a periodic structure of alternating GaN layers not intentionally doped with Mg and InGaN layers with high Mg doping, and the Mg doping concentration of the high Mg doping InGaN layer is greater than the Mg doping concentration of the magnesium-carbon co-doped GaN composite layer. The material layer containing the high Mg doping concentration is placed on the side of the hole injection layer away from the active layer, which not only ensures the crystal quality of the second superlattice layer when highly doped with Mg, but also increases the activated Mg concentration. In addition, the energy level of the Mg acceptor is deeper (about 170meV), and In atoms can reduce the activation energy of Mg and increase the activated Mg concentration.

[0047] Therefore, the present invention effectively reduces the self-compensation effect of Mg, increases the activated Mg concentration, increases the hole concentration, increases the effective hole injection efficiency, reduces electron overflow, and thus increases the radiation recombination efficiency of electrons and holes in the active layer, thereby improving the luminous efficiency of the light-emitting diode.

[0048] In some embodiments, the Mg doping concentration in the low Mg-doped AlGaN layer is 1×10 17 cm -3 ~1×10 18 cm -3 The Mg doping concentration of the highly Mg-doped InGaN layer is 1×10 20 cm -3 ~1×10 21 cm -3 .

[0049] For example, the Mg doping concentration in the low Mg-doped AlGaN layer is 1×10 17 cm -3 , 2×10 17 cm -3, 3×10 17 cm -3 , 4×10 17 cm -3 , 5×10 17 cm -3 , 6×10 17 cm -3 , 7×10 17 cm -3 , 8×10 17 cm -3 , 9×10 17 cm -3 or 1×10 18 cm -3 , but not limited to this.

[0050] For example, the Mg doping concentration of the highly Mg-doped InGaN layer is 1×10 20 cm -3 , 2×10 20 cm -3 , 3×10 20 cm -3 , 4×10 20 cm -3 , 5×10 20 cm -3 , 6×10 20 cm -3 , 7×10 20 cm -3 , 8×10 20 cm -3 , 9×10 20 cm -3 or 1×10 21 cm -3 , but not limited to this.

[0051] In some embodiments, see Figure 2 As shown, the MgC co-doped GaN composite layer includes a first MgC co-doped GaN layer 621, a second MgC co-doped GaN layer 622 and a third MgC co-doped GaN layer 623 sequentially deposited on the first superlattice layer along the epitaxial direction.

[0052] The Mg doping concentration of the highly Mg-doped InGaN layer is greater than the Mg doping concentration of the second Mg-carbon co-doped GaN layer, the Mg doping concentration of the second Mg-carbon co-doped GaN layer is greater than the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer, and the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer are both greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0053] By setting the Mg doping concentration between the first MgC co-doped GaN layer, the second MgC co-doped GaN layer and the third MgC co-doped GaN layer, while ensuring that the MgC co-doped GaN composite layer as a whole can replenish more holes, the lattice distortion and material degradation caused by high doping concentration are reduced, the effective hole mobility is improved, the leakage channel is reduced, and it is ensured that the holes in the subsequent epitaxial material layer can better diffuse to the active layer.

[0054] In some embodiments, the Mg doping concentration of the first MgC co-doped GaN layer and the Mg doping concentration of the third MgC co-doped GaN layer are both 1×10 18 cm -3 ~1×10 19 cm -3 The Mg doping concentration of the second MgC co-doped GaN layer is 1×10 19 cm -3 ~1×10 20 cm -3 .

[0055] Among them, the Mg doping concentration of the first MgC co-doped GaN layer, the second MgC co-doped GaN layer and the third MgC co-doped GaN layer should not be too low, which may easily lead to insufficient hole concentration in the overall MgC co-doped GaN composite layer. The Mg doping concentration of the first MgC co-doped GaN layer and the third MgC co-doped GaN layer should not be too high, which may easily aggravate the lattice distortion of the highly Mg-doped third MgC co-doped GaN layer and lead to an increase in leakage channels, and at the same time easily increase the self-compensation effect of Mg in the overall MgC co-doped GaN composite layer.

[0056] For example, the Mg doping concentration of the first Mg-C co-doped GaN layer is 1×10 18 cm -3 , 2×10 18 cm -3 , 3×10 18 cm -3 , 4×10 18 cm -3 , 5×10 18 cm -3 , 6×10 18 cm -3 , 7×10 18 cm -3 , 8×10 18 cm -3 , 9×10 18 cm -3 or 1×10 19 cm -3 , but not limited to this.

[0057] For example, the Mg doping concentration of the third MgC co-doped GaN layer is 1×10 18 cm -3 , 2×10 18 cm -3 , 3×10 18 cm -3 , 4×10 18 cm -3 , 5×10 18 cm -3 , 6×10 18 cm -3 , 7×10 18 cm -3 , 8×10 18 cm -3 , 9×10 18 cm -3 or 1×10 19 cm -3 , but not limited to this.

[0058] For example, the Mg doping concentration of the second Mg-C co-doped GaN layer is 1×10 19 cm -3 , 2×10 19 cm -3 , 3×10 19 cm -3 , 4×10 19 cm -3 , 5×10 19 cm -3 , 6×10 19 cm -3 , 7×10 19 cm -3 , 8×10 19 cm -3 , 9×10 19 cm -3 or 1×10 20 cm -3 , but not limited to this.

[0059] In some embodiments, the carbon doping concentration of the first magnesium-carbon co-doped GaN layer, the second magnesium-carbon co-doped GaN layer, and the third magnesium-carbon co-doped GaN layer is 1×10 17 cm -3 ~8×10 17 cm -3 .

[0060] Among them, the carbon doping concentration should not be too high. When the carbon doping concentration is too low, the compensation effect of carbon on the self-compensation effect of Mg is insufficient. When the carbon doping concentration is too high, carbon is more likely to form a complex with donor characteristics in the material layer, thereby forming self-compensation and affecting the hole concentration.

[0061] For example, the carbon doping concentration of the first magnesium-carbon co-doped GaN layer, the second magnesium-carbon co-doped GaN layer, and the third magnesium-carbon co-doped GaN layer is 1×10 17 cm -3 , 2×10 17 cm -3 , 3×10 17 cm -3 , 4×10 17 cm -3 , 5×10 17 cm -3 , 6×10 17 cm -3 , 7×10 17 cm -3 or 8×10 17 cm -3 , but not limited to this.

[0062] In some embodiments, the first MgC co-doped GaN layer, the second MgC co-doped GaN layer, and the third MgC co-doped GaN layer are all provided with V-shaped pits, and in the second superlattice layer, the non-intentionally Mg-doped GaN layer closest to the third MgC co-doped GaN layer fills and merges the V-shaped pits on the third MgC co-doped GaN layer.

[0063] V-shaped pits are provided in each sublayer of the magnesium-carbon co-doped GaN composite layer to enable carbon to be better incorporated into the material layer and to improve the hole injection efficiency.

[0064] In some embodiments, the number of periods of the first superlattice layer is 1 to 10, the thickness ratio a of the low Mg-doped AlGaN layer / the unintentionally Mg-doped AlGaN layer is 1≤a≤2, and the proportion of Al components in the unintentionally Mg-doped AlGaN layer and the low Mg-doped AlGaN layer is 0.01 to 0.1.

[0065] An exemplary number of periods of the first superlattice layer is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, but is not limited thereto.

[0066] The thickness ratio a of the low-Mg-doped AlGaN layer / the unintentionally Mg-doped AlGaN layer is 1, 1.2, 1.5, 1.7, 1.8 or 2, but is not limited thereto.

[0067] The proportion (molar fraction) of the Al component in the unintentionally Mg-doped AlGaN layer and the low-Mg-doped AlGaN layer is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1, but is not limited thereto.

[0068] When the Al component is too high, the leakage current is likely to increase. When the Al component is too low, the blocking effect of the material layer on electron overflow will be affected.

[0069] Preferably, a is 1.5≤a≤2, which can ensure that more Mg is doped in the first superlattice layer while ensuring that the holes in the low-Mg-doped AlGaN layer can diffuse into the non-intentionally Mg-doped AlGaN layer with weaker ionized impurity scattering, thereby obtaining a higher effective hole mobility.

[0070] In some embodiments, the number of periods of the second superlattice layer is 1 to 30, the thickness ratio b of the highly Mg-doped InGaN layer / the non-intentionally Mg-doped GaN layer is 1≤b≤2, and the proportion of In component in the highly Mg-doped InGaN layer is 0.01 to 0.1.

[0071] An exemplary number of periods of the second superlattice layer is 1, 3, 5, 8, 10, 12, 14, 15, 18, 20, 22, 25, 28 or 30, but is not limited thereto.

[0072] The thickness ratio b of the highly Mg-doped InGaN layer / the unintentionally Mg-doped GaN layer is 1, 1.2, 1.5, 1.7, 1.8 or 2, but is not limited thereto.

[0073] The proportion (molar fraction) of the In component in the highly Mg-doped InGaN layer is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1, but is not limited thereto.

[0074] When the In component is too low, it is easy to affect the increase of the activated Mg concentration. When the In component is too high, it is easy to increase the leakage current.

[0075] Among them, the electron blocking layer is AlInGaN, in which the proportion of Al component increases from 0.01 to 0.05 along the epitaxial direction, and the proportion of In component is 0.01, which can not only effectively limit electron overflow, but also reduce the blocking of holes, improve the injection efficiency of holes into the quantum well, reduce carrier Auger recombination, and improve the luminous efficiency of the light-emitting diode.

[0076] The P-type layer can be a P-type GaN layer, and the Mg doping concentration is 1×10 19 cm-3 ~1×10 21 cm -3 .

[0077] The N-type layer can be an N-type GaN layer, and the doping concentration of Si is 1×10 19 cm -3 ~5×10 19 cm -3 .

[0078] The active layer may be a periodic structure of alternately stacked InGaN quantum well layers and AlGaN quantum barrier layers.

[0079] Among them, the thickness of the first superlattice layer is 0.5nm~5nm, the thickness of the first magnesium-carbon co-doped GaN layer is 0.5nm~5nm, the thickness of the second magnesium-carbon co-doped GaN layer is 1nm~10nm, the thickness of the third magnesium-carbon co-doped GaN layer is 0.5nm~5nm, and the thickness of the second superlattice layer is 1nm~50nm.

[0080] Secondly, the present invention also provides a method for preparing a light-emitting diode epitaxial wafer, comprising:

[0081] providing a substrate,

[0082] depositing an epitaxial layer on the substrate,

[0083] The epitaxial layer includes a buffer layer, an undoped GaN layer, an N-type layer, an active layer, an electron blocking layer and a P-type layer sequentially deposited on the substrate along the epitaxial direction.

[0084] A hole injection layer is provided between the active layer and the electron blocking layer, and the hole injection layer comprises a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer sequentially deposited along the epitaxial direction.

[0085] The first superlattice layer is a periodic structure of an AlGaN layer not intentionally doped with Mg and an AlGaN layer with low Mg doping alternately stacked.

[0086] The second superlattice layer is a periodic structure composed of GaN layers not intentionally doped with Mg and InGaN layers highly doped with Mg alternately stacked.

[0087] The Mg doping concentration of the high Mg-doped InGaN layer is greater than the Mg doping concentration of the Mg-carbon co-doped GaN composite layer, and the Mg doping concentration of the Mg-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0088] In some embodiments, the magnesium-carbon co-doped GaN composite layer includes a first magnesium-carbon co-doped GaN layer, a second magnesium-carbon co-doped GaN layer, and a third magnesium-carbon co-doped GaN layer sequentially deposited on the first superlattice layer along the epitaxial direction.

[0089] The Mg doping concentration of the highly Mg-doped InGaN layer is greater than the Mg doping concentration of the second Mg-carbon co-doped GaN layer, the Mg doping concentration of the second Mg-carbon co-doped GaN layer is greater than the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer, and the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer are both greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0090] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0091] Example 1

[0092] First, the present invention provides a light-emitting diode epitaxial wafer, comprising a substrate and an epitaxial layer disposed on the substrate, wherein the epitaxial layer comprises a buffer layer, an undoped GaN layer, an N-type layer, an active layer, an electron blocking layer, and a P-type layer sequentially deposited on the substrate along an epitaxial direction.

[0093] A hole injection layer is provided between the active layer and the electron blocking layer, and the hole injection layer comprises a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer sequentially deposited along the epitaxial direction.

[0094] The first superlattice layer is a periodic structure of an AlGaN layer not intentionally doped with Mg and an AlGaN layer with low Mg doping alternately stacked.

[0095] The second superlattice layer is a periodic structure composed of GaN layers not intentionally doped with Mg and InGaN layers highly doped with Mg alternately stacked.

[0096] The Mg doping concentration of the high Mg-doped InGaN layer is greater than the Mg doping concentration of the Mg-carbon co-doped GaN composite layer, and the Mg doping concentration of the Mg-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0097] The Mg doping concentration in the low Mg-doped AlGaN layer is 3×10 17 cm -3 The Mg doping concentration of the highly Mg-doped InGaN layer is 1.6×10 20 cm -3 .

[0098] The magnesium-carbon co-doped GaN composite layer includes a first magnesium-carbon co-doped GaN layer, a second magnesium-carbon co-doped GaN layer, and a third magnesium-carbon co-doped GaN layer sequentially deposited on the first superlattice layer along the epitaxial direction.

[0099] The Mg doping concentration of the highly Mg-doped InGaN layer is greater than the Mg doping concentration of the second Mg-carbon co-doped GaN layer, the Mg doping concentration of the second Mg-carbon co-doped GaN layer is greater than the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer, and the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer are both greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0100] The Mg doping concentration of the first Mg-C co-doped GaN layer and the Mg doping concentration of the third Mg-C co-doped GaN layer are both 6×10 18 cm -3 The Mg doping concentration of the second MgC co-doped GaN layer is 4.6×10 19 cm -3 .

[0101] The carbon doping concentration of the first magnesium-carbon co-doped GaN layer, the second magnesium-carbon co-doped GaN layer and the third magnesium-carbon co-doped GaN layer is 3.5×10 17 cm -3 .

[0102] Among them, the number of periods of the first superlattice layer is 3, the thickness ratio a of the low Mg-doped AlGaN layer / the unintentionally Mg-doped AlGaN layer is 1.5, and the proportion of Al components in the unintentionally Mg-doped AlGaN layer and the low Mg-doped AlGaN layer is 0.06.

[0103] The number of periods of the second superlattice layer is 1 to 30, the thickness ratio b of the highly Mg-doped InGaN layer / the non-intentionally Mg-doped GaN layer is 1, and the proportion of In component in the highly Mg-doped InGaN layer is 0.05.

[0104] The electron blocking layer is AlInGaN, wherein the proportion of the Al component increases from 0.01 to 0.05 along the epitaxial direction, and the proportion of the In component is 0.01.

[0105] The P-type layer can be a P-type GaN layer, and the Mg doping concentration is 1×10 20 cm -3 .

[0106] The N-type layer can be an N-type GaN layer, and the doping concentration of Si is 5×10 19 cm -3 .

[0107] The active layer may be a periodic structure of alternately stacked InGaN quantum well layers and AlGaN quantum barrier layers.

[0108] Among them, the thickness of the first superlattice layer is 3.6nm, the thickness of the first magnesium-carbon co-doped GaN layer is 2.3nm, the thickness of the second magnesium-carbon co-doped GaN layer is 6.4nm, the thickness of the third magnesium-carbon co-doped GaN layer is 2.3nm, and the thickness of the second superlattice layer is 30nm.

[0109] Example 2

[0110] First, the present invention provides a light-emitting diode epitaxial wafer, comprising a substrate and an epitaxial layer disposed on the substrate, wherein the epitaxial layer comprises a buffer layer, an undoped GaN layer, an N-type layer, an active layer, an electron blocking layer, and a P-type layer sequentially deposited on the substrate along an epitaxial direction.

[0111] A hole injection layer is provided between the active layer and the electron blocking layer, and the hole injection layer comprises a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer sequentially deposited along the epitaxial direction.

[0112] The first superlattice layer is a periodic structure of an AlGaN layer not intentionally doped with Mg and an AlGaN layer with low Mg doping alternately stacked.

[0113] The second superlattice layer is a periodic structure composed of GaN layers not intentionally doped with Mg and InGaN layers highly doped with Mg alternately stacked.

[0114] The Mg doping concentration of the high Mg-doped InGaN layer is greater than the Mg doping concentration of the Mg-carbon co-doped GaN composite layer, and the Mg doping concentration of the Mg-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0115] The Mg doping concentration in the low Mg-doped AlGaN layer is 1×10 18 cm -3 The Mg doping concentration of the highly Mg-doped InGaN layer is 1×10 21 cm -3 .

[0116] The magnesium-carbon co-doped GaN composite layer includes a first magnesium-carbon co-doped GaN layer, a second magnesium-carbon co-doped GaN layer, and a third magnesium-carbon co-doped GaN layer sequentially deposited on the first superlattice layer along the epitaxial direction.

[0117] The Mg doping concentration of the highly Mg-doped InGaN layer is greater than the Mg doping concentration of the second Mg-carbon co-doped GaN layer, the Mg doping concentration of the second Mg-carbon co-doped GaN layer is greater than the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer, and the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer are both greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0118] The Mg doping concentration of the first Mg-C co-doped GaN layer and the Mg doping concentration of the third Mg-C co-doped GaN layer are both 1×10 19 cm -3 The Mg doping concentration of the second MgC co-doped GaN layer is 1×10 20 cm -3 .

[0119] The carbon doping concentration of the first magnesium-carbon co-doped GaN layer, the second magnesium-carbon co-doped GaN layer and the third magnesium-carbon co-doped GaN layer is 3.5×10 17 cm -3 .

[0120] Among them, the number of periods of the first superlattice layer is 3, the thickness ratio a of the low Mg-doped AlGaN layer / the unintentionally Mg-doped AlGaN layer is 1.5, and the proportion of Al components in the unintentionally Mg-doped AlGaN layer and the low Mg-doped AlGaN layer is 0.06.

[0121] The number of periods of the second superlattice layer is 1 to 30, the thickness ratio b of the highly Mg-doped InGaN layer / the non-intentionally Mg-doped GaN layer is 1, and the proportion of In component in the highly Mg-doped InGaN layer is 0.05.

[0122] The electron blocking layer is AlInGaN, wherein the proportion of the Al component increases from 0.01 to 0.05 along the epitaxial direction, and the proportion of the In component is 0.01.

[0123] The P-type layer can be a P-type GaN layer, and the Mg doping concentration is 1×10 20 cm -3 .

[0124] The N-type layer can be an N-type GaN layer, and the doping concentration of Si is 5×10 19 cm -3 .

[0125] The active layer may be a periodic structure of alternately stacked InGaN quantum well layers and AlGaN quantum barrier layers.

[0126] Among them, the thickness of the first superlattice layer is 3.6nm, the thickness of the first magnesium-carbon co-doped GaN layer is 2.3nm, the thickness of the second magnesium-carbon co-doped GaN layer is 6.4nm, the thickness of the third magnesium-carbon co-doped GaN layer is 2.3nm, and the thickness of the second superlattice layer is 30nm.

[0127] Example 3

[0128] First, the present invention provides a light-emitting diode epitaxial wafer, comprising a substrate and an epitaxial layer disposed on the substrate, wherein the epitaxial layer comprises a buffer layer, an undoped GaN layer, an N-type layer, an active layer, an electron blocking layer, and a P-type layer sequentially deposited on the substrate along an epitaxial direction.

[0129] A hole injection layer is provided between the active layer and the electron blocking layer, and the hole injection layer comprises a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer sequentially deposited along the epitaxial direction.

[0130] The first superlattice layer is a periodic structure of an AlGaN layer not intentionally doped with Mg and an AlGaN layer with low Mg doping alternately stacked.

[0131] The second superlattice layer is a periodic structure composed of GaN layers not intentionally doped with Mg and InGaN layers highly doped with Mg alternately stacked.

[0132] The Mg doping concentration of the high Mg-doped InGaN layer is greater than the Mg doping concentration of the Mg-carbon co-doped GaN composite layer, and the Mg doping concentration of the Mg-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0133] The Mg doping concentration in the low Mg-doped AlGaN layer is 5×10 17 cm -3 The Mg doping concentration of the highly Mg-doped InGaN layer is 5×10 20 cm -3 .

[0134] The magnesium-carbon co-doped GaN composite layer includes a first magnesium-carbon co-doped GaN layer, a second magnesium-carbon co-doped GaN layer, and a third magnesium-carbon co-doped GaN layer sequentially deposited on the first superlattice layer along the epitaxial direction.

[0135] The Mg doping concentration of the highly Mg-doped InGaN layer is greater than the Mg doping concentration of the second Mg-carbon co-doped GaN layer, the Mg doping concentration of the second Mg-carbon co-doped GaN layer is greater than the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer, and the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer are both greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0136] The Mg doping concentration of the first Mg-C co-doped GaN layer and the Mg doping concentration of the third Mg-C co-doped GaN layer are both 1×10 18 cm -3 The Mg doping concentration of the second MgC co-doped GaN layer is 1×10 19 cm -3 .

[0137] The carbon doping concentration of the first magnesium-carbon co-doped GaN layer, the second magnesium-carbon co-doped GaN layer and the third magnesium-carbon co-doped GaN layer is 3.5×10 17 cm -3 .

[0138] Among them, the number of periods of the first superlattice layer is 3, the thickness ratio a of the low Mg-doped AlGaN layer / the unintentionally Mg-doped AlGaN layer is 1.5, and the proportion of Al components in the unintentionally Mg-doped AlGaN layer and the low Mg-doped AlGaN layer is 0.06.

[0139] The number of periods of the second superlattice layer is 1 to 30, the thickness ratio b of the highly Mg-doped InGaN layer / the non-intentionally Mg-doped GaN layer is 1, and the proportion of In component in the highly Mg-doped InGaN layer is 0.05.

[0140] The electron blocking layer is AlInGaN, wherein the proportion of the Al component increases from 0.01 to 0.05 along the epitaxial direction, and the proportion of the In component is 0.01.

[0141] The P-type layer can be a P-type GaN layer, and the Mg doping concentration is 1×10 20 cm -3 .

[0142] The N-type layer can be an N-type GaN layer, and the doping concentration of Si is 5×10 19 cm -3 .

[0143] The active layer may be a periodic structure of alternately stacked InGaN quantum well layers and AlGaN quantum barrier layers.

[0144] Among them, the thickness of the first superlattice layer is 3.6nm, the thickness of the first magnesium-carbon co-doped GaN layer is 2.3nm, the thickness of the second magnesium-carbon co-doped GaN layer is 6.4nm, the thickness of the third magnesium-carbon co-doped GaN layer is 2.3nm, and the thickness of the second superlattice layer is 30nm.

[0145] Example 4

[0146] First, the present invention provides a light-emitting diode epitaxial wafer, comprising a substrate and an epitaxial layer disposed on the substrate, wherein the epitaxial layer comprises a buffer layer, an undoped GaN layer, an N-type layer, an active layer, an electron blocking layer, and a P-type layer sequentially deposited on the substrate along an epitaxial direction.

[0147] A hole injection layer is provided between the active layer and the electron blocking layer, and the hole injection layer comprises a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer sequentially deposited along the epitaxial direction.

[0148] The first superlattice layer is a periodic structure of an AlGaN layer not intentionally doped with Mg and an AlGaN layer with low Mg doping alternately stacked.

[0149] The second superlattice layer is a periodic structure composed of GaN layers not intentionally doped with Mg and InGaN layers highly doped with Mg alternately stacked.

[0150] The Mg doping concentration of the high Mg-doped InGaN layer is greater than the Mg doping concentration of the Mg-carbon co-doped GaN composite layer, and the Mg doping concentration of the Mg-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0151] The Mg doping concentration in the low Mg-doped AlGaN layer is 3×10 17 cm -3 The Mg doping concentration of the highly Mg-doped InGaN layer is 1.6×10 20 cm -3 .

[0152] The magnesium-carbon co-doped GaN composite layer includes a first magnesium-carbon co-doped GaN layer, a second magnesium-carbon co-doped GaN layer, and a third magnesium-carbon co-doped GaN layer sequentially deposited on the first superlattice layer along the epitaxial direction.

[0153] The Mg doping concentration of the highly Mg-doped InGaN layer is greater than the Mg doping concentration of the second Mg-carbon co-doped GaN layer, the Mg doping concentration of the second Mg-carbon co-doped GaN layer is greater than the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer, and the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer are both greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0154] The Mg doping concentration of the first Mg-C co-doped GaN layer and the Mg doping concentration of the third Mg-C co-doped GaN layer are both 6×10 18 cm -3 The Mg doping concentration of the second MgC co-doped GaN layer is 4.6×10 19 cm -3 .

[0155] The carbon doping concentration of the first magnesium-carbon co-doped GaN layer, the second magnesium-carbon co-doped GaN layer and the third magnesium-carbon co-doped GaN layer is 1×10 18 cm -3 .

[0156] Among them, the number of periods of the first superlattice layer is 3, the thickness ratio a of the low Mg-doped AlGaN layer / the unintentionally Mg-doped AlGaN layer is 1.5, and the proportion of Al components in the unintentionally Mg-doped AlGaN layer and the low Mg-doped AlGaN layer is 0.06.

[0157] The number of periods of the second superlattice layer is 1 to 30, the thickness ratio b of the highly Mg-doped InGaN layer / the non-intentionally Mg-doped GaN layer is 1, and the proportion of In component in the highly Mg-doped InGaN layer is 0.05.

[0158] The electron blocking layer is AlInGaN, wherein the proportion of the Al component increases from 0.01 to 0.05 along the epitaxial direction, and the proportion of the In component is 0.01.

[0159] The P-type layer can be a P-type GaN layer, and the Mg doping concentration is 1×10 20 cm -3 .

[0160] The N-type layer can be an N-type GaN layer, and the doping concentration of Si is 5×10 19 cm -3 .

[0161] The active layer may be a periodic structure of alternately stacked InGaN quantum well layers and AlGaN quantum barrier layers.

[0162] Among them, the thickness of the first superlattice layer is 3.6nm, the thickness of the first magnesium-carbon co-doped GaN layer is 2.3nm, the thickness of the second magnesium-carbon co-doped GaN layer is 6.4nm, the thickness of the third magnesium-carbon co-doped GaN layer is 2.3nm, and the thickness of the second superlattice layer is 30nm.

[0163] Example 5

[0164] First, the present invention provides a light-emitting diode epitaxial wafer, comprising a substrate and an epitaxial layer disposed on the substrate, wherein the epitaxial layer comprises a buffer layer, an undoped GaN layer, an N-type layer, an active layer, an electron blocking layer, and a P-type layer sequentially deposited on the substrate along an epitaxial direction.

[0165] A hole injection layer is provided between the active layer and the electron blocking layer, and the hole injection layer comprises a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer sequentially deposited along the epitaxial direction.

[0166] The first superlattice layer is a periodic structure of an AlGaN layer not intentionally doped with Mg and an AlGaN layer with low Mg doping alternately stacked.

[0167] The second superlattice layer is a periodic structure composed of GaN layers not intentionally doped with Mg and InGaN layers highly doped with Mg alternately stacked.

[0168] The Mg doping concentration of the high Mg-doped InGaN layer is greater than the Mg doping concentration of the Mg-carbon co-doped GaN composite layer, and the Mg doping concentration of the Mg-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0169] The Mg doping concentration in the low Mg-doped AlGaN layer is 3×10 17 cm -3 The Mg doping concentration of the highly Mg-doped InGaN layer is 1.6×10 20 cm -3 .

[0170] The magnesium-carbon co-doped GaN composite layer includes a first magnesium-carbon co-doped GaN layer, a second magnesium-carbon co-doped GaN layer, and a third magnesium-carbon co-doped GaN layer sequentially deposited on the first superlattice layer along the epitaxial direction.

[0171] The Mg doping concentration of the highly Mg-doped InGaN layer is greater than the Mg doping concentration of the second Mg-carbon co-doped GaN layer, the Mg doping concentration of the second Mg-carbon co-doped GaN layer is greater than the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer, and the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer are both greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0172] The Mg doping concentration of the first Mg-C co-doped GaN layer and the Mg doping concentration of the third Mg-C co-doped GaN layer are both 6×10 18 cm -3 The Mg doping concentration of the second MgC co-doped GaN layer is 4.6×10 19 cm -3 .

[0173] The carbon doping concentration of the first magnesium-carbon co-doped GaN layer, the second magnesium-carbon co-doped GaN layer and the third magnesium-carbon co-doped GaN layer is 8×10 17 cm -3 .

[0174] Among them, the number of periods of the first superlattice layer is 3, the thickness ratio a of the low Mg-doped AlGaN layer / the unintentionally Mg-doped AlGaN layer is 1.5, and the proportion of Al components in the unintentionally Mg-doped AlGaN layer and the low Mg-doped AlGaN layer is 0.06.

[0175] The number of periods of the second superlattice layer is 1 to 30, the thickness ratio b of the highly Mg-doped InGaN layer / the non-intentionally Mg-doped GaN layer is 1, and the proportion of In component in the highly Mg-doped InGaN layer is 0.05.

[0176] The electron blocking layer is AlInGaN, wherein the proportion of the Al component increases from 0.01 to 0.05 along the epitaxial direction, and the proportion of the In component is 0.01.

[0177] The P-type layer can be a P-type GaN layer, and the Mg doping concentration is 1×10 20 cm -3 .

[0178] The N-type layer can be an N-type GaN layer, and the doping concentration of Si is 5×10 19 cm -3 .

[0179] The active layer may be a periodic structure of alternately stacked InGaN quantum well layers and AlGaN quantum barrier layers.

[0180] Among them, the thickness of the first superlattice layer is 3.6nm, the thickness of the first magnesium-carbon co-doped GaN layer is 2.3nm, the thickness of the second magnesium-carbon co-doped GaN layer is 6.4nm, the thickness of the third magnesium-carbon co-doped GaN layer is 2.3nm, and the thickness of the second superlattice layer is 30nm.

[0181] Example 6

[0182] First, the present invention provides a light-emitting diode epitaxial wafer, comprising a substrate and an epitaxial layer disposed on the substrate, wherein the epitaxial layer comprises a buffer layer, an undoped GaN layer, an N-type layer, an active layer, an electron blocking layer, and a P-type layer sequentially deposited on the substrate along an epitaxial direction.

[0183] A hole injection layer is provided between the active layer and the electron blocking layer, and the hole injection layer comprises a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer sequentially deposited along the epitaxial direction.

[0184] The first superlattice layer is a periodic structure of an AlGaN layer not intentionally doped with Mg and an AlGaN layer with low Mg doping alternately stacked.

[0185] The second superlattice layer is a periodic structure composed of GaN layers not intentionally doped with Mg and InGaN layers highly doped with Mg alternately stacked.

[0186] The Mg doping concentration of the high Mg-doped InGaN layer is greater than the Mg doping concentration of the Mg-carbon co-doped GaN composite layer, and the Mg doping concentration of the Mg-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0187] The Mg doping concentration in the low Mg-doped AlGaN layer is 3×10 17 cm -3 The Mg doping concentration of the highly Mg-doped InGaN layer is 1.6×10 20 cm -3 .

[0188] The magnesium-carbon co-doped GaN composite layer includes a first magnesium-carbon co-doped GaN layer, a second magnesium-carbon co-doped GaN layer, and a third magnesium-carbon co-doped GaN layer sequentially deposited on the first superlattice layer along the epitaxial direction.

[0189] The Mg doping concentration of the highly Mg-doped InGaN layer is greater than the Mg doping concentration of the second Mg-carbon co-doped GaN layer, the Mg doping concentration of the second Mg-carbon co-doped GaN layer is greater than the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer, and the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer are both greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0190] The Mg doping concentration of the first Mg-C co-doped GaN layer and the Mg doping concentration of the third Mg-C co-doped GaN layer are both 6×10 18 cm -3 The Mg doping concentration of the second MgC co-doped GaN layer is 4.6×10 19 cm -3 .

[0191] Among them, the first magnesium-carbon co-doped GaN layer, the second magnesium-carbon co-doped GaN layer and the third magnesium-carbon co-doped GaN layer are all provided with V-shaped pits, and in the second superlattice layer, the non-intentionally Mg-doped GaN layer closest to the third magnesium-carbon co-doped GaN layer fills and merges the V-shaped pits on the third magnesium-carbon co-doped GaN layer.

[0192] The carbon doping concentration of the first magnesium-carbon co-doped GaN layer, the second magnesium-carbon co-doped GaN layer and the third magnesium-carbon co-doped GaN layer is 3.5×10 17 cm -3 .

[0193] Among them, the number of periods of the first superlattice layer is 3, the thickness ratio a of the low Mg-doped AlGaN layer / the unintentionally Mg-doped AlGaN layer is 1.5, and the proportion of Al components in the unintentionally Mg-doped AlGaN layer and the low Mg-doped AlGaN layer is 0.06.

[0194] The number of periods of the second superlattice layer is 1 to 30, the thickness ratio b of the highly Mg-doped InGaN layer / the non-intentionally Mg-doped GaN layer is 1, and the proportion of In component in the highly Mg-doped InGaN layer is 0.05.

[0195] The electron blocking layer is AlInGaN, wherein the proportion of the Al component increases from 0.01 to 0.05 along the epitaxial direction, and the proportion of the In component is 0.01.

[0196] The P-type layer can be a P-type GaN layer, and the Mg doping concentration is 1×10 20 cm -3 .

[0197] The N-type layer can be an N-type GaN layer, and the doping concentration of Si is 5×10 19 cm -3 .

[0198] The active layer may be a periodic structure of alternately stacked InGaN quantum well layers and AlGaN quantum barrier layers.

[0199] Among them, the thickness of the first superlattice layer is 3.6nm, the thickness of the first magnesium-carbon co-doped GaN layer is 2.3nm, the thickness of the second magnesium-carbon co-doped GaN layer is 6.4nm, the thickness of the third magnesium-carbon co-doped GaN layer is 2.3nm, and the thickness of the second superlattice layer is 30nm.

[0200] Example 7

[0201] First, the present invention provides a light-emitting diode epitaxial wafer, comprising a substrate and an epitaxial layer disposed on the substrate, wherein the epitaxial layer comprises a buffer layer, an undoped GaN layer, an N-type layer, an active layer, an electron blocking layer, and a P-type layer sequentially deposited on the substrate along an epitaxial direction.

[0202] A hole injection layer is provided between the active layer and the electron blocking layer, and the hole injection layer comprises a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer sequentially deposited along the epitaxial direction.

[0203] The first superlattice layer is a periodic structure of an AlGaN layer not intentionally doped with Mg and an AlGaN layer with low Mg doping alternately stacked.

[0204] The second superlattice layer is a periodic structure composed of GaN layers not intentionally doped with Mg and InGaN layers highly doped with Mg alternately stacked.

[0205] The Mg doping concentration of the high Mg-doped InGaN layer is greater than the Mg doping concentration of the Mg-carbon co-doped GaN composite layer, and the Mg doping concentration of the Mg-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

[0206] The Mg doping concentration in the low Mg-doped AlGaN layer is 3×10 17 cm -3 The Mg doping concentration of the highly Mg-doped InGaN layer is 1.6×10 20 cm -3 .

[0207] The Mg-C co-doped GaN composite layer comprises a first Mg-C co-doped GaN layer, a second Mg-C co-doped GaN layer and a third Mg-C co-doped GaN layer sequentially deposited on the first superlattice layer along the epitaxial direction, and the Mg doping concentrations of the first Mg-C co-doped GaN layer, the second Mg-C co-doped GaN layer and the third Mg-C co-doped GaN layer are all 1×10 19 cm -3 .

[0208] The carbon doping concentration of the first magnesium-carbon co-doped GaN layer, the second magnesium-carbon co-doped GaN layer and the third magnesium-carbon co-doped GaN layer is 3.5×10 17 cm -3 .

[0209] Among them, the number of periods of the first superlattice layer is 3, the thickness ratio a of the low Mg-doped AlGaN layer / the unintentionally Mg-doped AlGaN layer is 1.5, and the proportion of Al components in the unintentionally Mg-doped AlGaN layer and the low Mg-doped AlGaN layer is 0.06.

[0210] The number of periods of the second superlattice layer is 1 to 30, the thickness ratio b of the highly Mg-doped InGaN layer / the non-intentionally Mg-doped GaN layer is 1, and the proportion of In component in the highly Mg-doped InGaN layer is 0.05.

[0211] The electron blocking layer is AlInGaN, wherein the proportion of the Al component increases from 0.01 to 0.05 along the epitaxial direction, and the proportion of the In component is 0.01.

[0212] The P-type layer can be a P-type GaN layer, and the Mg doping concentration is 1×10 20 cm -3 .

[0213] The N-type layer can be an N-type GaN layer, and the doping concentration of Si is 5×10 19 cm -3 .

[0214] The active layer may be a periodic structure of alternately stacked InGaN quantum well layers and AlGaN quantum barrier layers.

[0215] Among them, the thickness of the first superlattice layer is 3.6nm, the thickness of the first magnesium-carbon co-doped GaN layer is 2.3nm, the thickness of the second magnesium-carbon co-doped GaN layer is 6.4nm, the thickness of the third magnesium-carbon co-doped GaN layer is 2.3nm, and the thickness of the second superlattice layer is 30nm.

[0216] Comparative Example 1

[0217] The difference between this comparative example and Example 1 is that in this comparative example, the Mg doping concentration of the low Mg-doped AlGaN layer, the Mg-carbon co-doped GaN composite layer, and the high Mg-doped InGaN layer in the hole injection layer is 1×10 19 cm -3 .

[0218] Comparative Example 2

[0219] The difference between this comparative example and Example 1 is that in this comparative example, the first superlattice layer is replaced by a low-Mg-doped AlGaN layer, and the Mg doping concentration of the low-Mg-doped AlGaN layer is 3×10 17 cm -3 , with a thickness of 3.6 nm, and the second superlattice layer is replaced by a highly Mg-doped InGaN layer, and the Mg doping concentration of the highly Mg-doped InGaN layer is 1.6×10 20 cm -3 , with a thickness of 30nm.

[0220] Comparative Example 3

[0221] The difference between this comparative example and Example 1 is that this comparative example does not include a hole injection layer.

[0222] Performance testing:

[0223] 1) Experimental group: Example 1 to Example 7, Comparative Example 1 to Comparative Example 3

[0224] 2) Test items:

[0225] The epitaxial wafers prepared in each experimental group were made into 10mil*24mil chips, and 300 LED chips were extracted from each group, and their brightness was tested at a current of 120mA.

[0226] 3) Test results:

[0227] The average brightness of each experimental group was calculated, and the brightness improvement rate of Examples 1 to 7 and Comparative Examples 1 to 2 relative to Comparative Example 3 was calculated to represent the improvement rate of luminous efficiency.

[0228] The test results are as follows:

[0229]

[0230]

[0231] By comparing Examples 1 to 3 with Comparative Example 1, it can be seen that the Mg doping concentration of the high Mg-doped InGaN layer is greater than the Mg doping concentration of the Mg-carbon co-doped GaN composite layer, and the Mg doping concentration of the Mg-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low Mg-doped AlGaN layer. The setting can effectively improve the luminous efficiency. By comparing Example 1, Comparative Example 2 and Comparative Example 3, it can be seen that there is a synergistic effect between the first superlattice layer, the Mg-carbon co-doped GaN composite layer and the second superlattice layer of the present application. By comparing Example 1, Example 4 and Example 5, it can be seen that the carbon doping concentration in the Mg-carbon co-doped GaN composite layer has an impact on the luminous efficiency. By comparing Example 1, Example 2 and Example 6, compared with Example 2, the Mg doping concentration in Example 6 is lower, but it can achieve a luminous efficiency equivalent to that of Example 2. It can be seen that the setting of the V-shaped pit in the Mg-carbon co-doped GaN composite layer can improve the luminous efficiency. By comparing Example 1 with Example 7, it can be seen that the different Mg doping concentration settings of each sublayer in the Mg-carbon co-doped GaN composite layer can improve the luminous efficiency.

[0232] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents suggested above. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the solution of the present invention.

Claims

1. A light emitting diode epitaxial wafer comprising a substrate and an epitaxial layer disposed on the substrate, characterized in that: The epitaxial layer includes a buffer layer, an undoped GaN layer, an N-type layer, an active layer, an electron blocking layer and a P-type layer sequentially deposited on the substrate along the epitaxial direction. A hole injection layer is provided between the active layer and the electron blocking layer, and the hole injection layer comprises a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer sequentially deposited along the epitaxial direction. The first superlattice layer is a periodic structure of an AlGaN layer not intentionally doped with Mg and an AlGaN layer with low Mg doping alternately stacked. The second superlattice layer is a periodic structure composed of GaN layers not intentionally doped with Mg and InGaN layers highly doped with Mg alternately stacked. The Mg doping concentration of the high Mg-doped InGaN layer is greater than the Mg doping concentration of the Mg-carbon co-doped GaN composite layer, and the Mg doping concentration of the Mg-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

2. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The Mg doping concentration in the low Mg-doped AlGaN layer is 1×10 17 cm -3 ~1×10 18 cm -3 The Mg doping concentration of the highly Mg-doped InGaN layer is 1×10 20 cm -3 ~1×10 21 cm -3 .

3. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The magnesium-carbon co-doped GaN composite layer includes a first magnesium-carbon co-doped GaN layer, a second magnesium-carbon co-doped GaN layer, and a third magnesium-carbon co-doped GaN layer sequentially deposited on the first superlattice layer along the epitaxial direction. The Mg doping concentration of the highly Mg-doped InGaN layer is greater than the Mg doping concentration of the second Mg-carbon co-doped GaN layer, the Mg doping concentration of the second Mg-carbon co-doped GaN layer is greater than the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer, and the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer are both greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

4. The light emitting diode epitaxial wafer according to claim 3, characterized in that: The Mg doping concentration of the first MgC co-doped GaN layer and the Mg doping concentration of the third MgC co-doped GaN layer are both 1×10 18 cm -3 ~1×10 19 cm -3 The Mg doping concentration of the second MgC co-doped GaN layer is 1×10 19 cm -3 ~1×10 20 cm -3 .

5. The light emitting diode epitaxial wafer according to claim 3, characterized in that: The carbon doping concentration of the first magnesium-carbon co-doped GaN layer, the second magnesium-carbon co-doped GaN layer, and the third magnesium-carbon co-doped GaN layer is 1×10 17 cm -3 ~8×10 17 cm -3 .

6. The light emitting diode epitaxial wafer according to claim 3, characterized in that: The first magnesium-carbon co-doped GaN layer, the second magnesium-carbon co-doped GaN layer and the third magnesium-carbon co-doped GaN layer are all provided with V-shaped pits. In the second superlattice layer, the non-intentionally Mg-doped GaN layer closest to the third magnesium-carbon co-doped GaN layer fills and merges the V-shaped pits on the third magnesium-carbon co-doped GaN layer.

7. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The number of periods of the first superlattice layer is 1 to 10, the thickness ratio a of the low Mg-doped AlGaN layer / the unintentionally Mg-doped AlGaN layer is 1≤a≤2, and the proportion of Al components in the unintentionally Mg-doped AlGaN layer and the low Mg-doped AlGaN layer is 0.01 to 0.

1.

8. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The number of periods of the second superlattice layer is 1 to 30, the thickness ratio b of the highly Mg-doped InGaN layer / the unintentionally Mg-doped GaN layer is 1≤b≤2, and the proportion of In component in the highly Mg-doped InGaN layer is 0.01 to 0.

1.

9. A method for preparing a light-emitting diode epitaxial wafer, characterized in that: include: providing a substrate, depositing an epitaxial layer on the substrate, The epitaxial layer includes a buffer layer, an undoped GaN layer, an N-type layer, an active layer, an electron blocking layer and a P-type layer sequentially deposited on the substrate along the epitaxial direction. A hole injection layer is provided between the active layer and the electron blocking layer, and the hole injection layer comprises a first superlattice layer, a magnesium-carbon co-doped GaN composite layer and a second superlattice layer sequentially deposited along the epitaxial direction. The first superlattice layer is a periodic structure of an AlGaN layer not intentionally doped with Mg and an AlGaN layer with low Mg doping alternately stacked. The second superlattice layer is a periodic structure composed of GaN layers not intentionally doped with Mg and InGaN layers highly doped with Mg alternately stacked. The Mg doping concentration of the high Mg-doped InGaN layer is greater than the Mg doping concentration of the Mg-carbon co-doped GaN composite layer, and the Mg doping concentration of the Mg-carbon co-doped GaN composite layer is greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

10. The preparation method according to claim 9, characterized in that The magnesium-carbon co-doped GaN composite layer includes a first magnesium-carbon co-doped GaN layer, a second magnesium-carbon co-doped GaN layer, and a third magnesium-carbon co-doped GaN layer sequentially deposited on the first superlattice layer along the epitaxial direction. The Mg doping concentration of the highly Mg-doped InGaN layer is greater than the Mg doping concentration of the second Mg-carbon co-doped GaN layer, the Mg doping concentration of the second Mg-carbon co-doped GaN layer is greater than the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer, and the Mg doping concentration of the first Mg-carbon co-doped GaN layer and the Mg doping concentration of the third Mg-carbon co-doped GaN layer are both greater than the Mg doping concentration of the low Mg-doped AlGaN layer.

Images