CN109755362B

CN109755362B - Nitride light-emitting diode with high luminous efficiency

Info

Publication number: CN109755362B
Application number: CN201910033337.5A
Authority: CN
Inventors: 顾伟
Original assignee: Jiangxi Zhao Chi Semiconductor Co Ltd
Current assignee: Jiangxi Zhao Chi Semiconductor Co Ltd
Priority date: 2019-01-14
Filing date: 2019-01-14
Publication date: 2021-10-01
Anticipated expiration: 2039-01-14
Also published as: CN109755362A

Abstract

The invention discloses a nitride light-emitting diode with high luminous efficiency, which comprises a substrate, and a buffer layer, a non-doped nitride layer, an n-type nitride layer, an active layer, an electron blocking layer and a p-type nitride layer which are sequentially arranged on the substrate; wherein: the active layer is a multi-quantum well structure formed by alternately stacking a plurality of well layers and barrier layers, and the plurality of well layers and barrier layers are positive integers greater than 2. The invention has the advantages that: the barrier layer of the nitride light emitting diode active layer is divided into a first barrier layer, a second barrier layer and a third barrier layer according to different Si doping concentrations, lower Si doping is used for the first barrier layer to obtain low crystal surface roughness, smooth covering of the well layer is achieved, moderate Si doping is used for the second barrier layer to achieve high crystal quality and low resistance value, higher Si doping is used for the third barrier layer to obtain more stress release, and low operating voltage and high light emitting efficiency of the nitride light emitting diode are achieved.

Description

Nitride light-emitting diode with high luminous efficiency

Technical Field

The invention relates to the technical field of semiconductors, in particular to a nitride light-emitting diode with high luminous efficiency.

Background

Light Emitting Diodes (LEDs) have gradually replaced conventional illumination light sources as a highly efficient and reliable solid-state lighting device, and become the mainstream of the market. The existing white light source of LED illumination mainly uses blue light nitride light emitting diode to excite yellow fluorescent powder to mix light, an epitaxial structure of the nitride light emitting diode is generally that a buffer layer, a non-doped nitride layer, an n-type nitride layer, an active layer, an electron blocking layer and a p-type nitride layer are sequentially prepared on an epitaxial substrate, wherein the active layer is of a multi-quantum well structure and is formed by alternately stacking a plurality of indium gallium nitride well layers and gallium nitride barrier layers, and the active layer can limit electrons and holes through the design of the structure and improve the recombination efficiency of the electrons and the holes in the active layer.

For epitaxial growth of the ingan well layer, since the incorporation capability of indium atoms has an obvious correlation with temperature, that is, the concentration of indium in the ingan decreases with the increase of the growth temperature, the ingan well layer is usually grown at a relatively low temperature (for example, the growth temperature of the ingan well layer of a blue-light nitride light emitting diode is about 810 ℃), the crystal quality of the ingan well layer grown at the relatively low temperature is poor, the surface roughness of the crystal is large, and the barrier layer grown at a relatively high temperature (for example, the growth temperature of the gallium nitride barrier layer of the blue-light nitride light emitting diode is about 900 ℃) can smoothly cover the ingan well layer in the active layer and improve the crystal quality of the active layer.

The gallium nitride barrier layer in current nitride light emitting diodes is doped with silicon (Si) to reduce its resistance value, which lowers the operating voltage of the nitride light emitting diode. However, the gallium nitride barrier layer with more Si doping can reduce the crystal quality of the gallium nitride barrier layer and increase the stress release, and the gallium nitride barrier layer with increased stress release can make the adjacent indium gallium nitride well layer receive a smaller piezoelectric polarization effect, so as to obtain better electron and hole recombination efficiency on the indium gallium nitride well layer. The Si doping concentration in the gallium nitride barrier layer can affect the surface roughness and the crystal quality of the gallium nitride barrier layer, and can also affect the resistance value and the stress condition of the gallium nitride barrier layer, so that the selection and the regulation of the Si doping concentration are very important for the operating voltage and the luminous efficiency of the nitride light-emitting diode when the gallium nitride barrier layer grows.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides a nitride light emitting diode with high luminous efficiency, which solves the problem that the luminous efficiency of the nitride light emitting diode is reduced due to poor crystal quality of an active layer caused by low growth temperature of a well layer in the prior art.

(II) technical scheme

The invention provides a nitride light emitting diode with high luminous efficiency, in the nitride light emitting diode, a barrier layer of an active layer selects different Si doping concentrations at different growth stages so as to give consideration to the smooth covering and stress releasing of the barrier layer to a well layer and the high crystal quality and low resistance value of the barrier layer, thereby realizing the nitride light emitting diode with low operating voltage and high luminous efficiency.

In order to realize the purpose, the invention provides the following technical scheme: a nitride LED with high luminous efficiency comprises a substrate, and a buffer layer, a non-doped nitride layer, an n-type nitride layer, an active layer, an electron blocking layer and a nitride layer sequentially arranged on the substrateA p-type nitride layer; wherein: the active layer is of a multi-quantum well structure formed by alternately stacking a plurality of well layers and barrier layers, the plurality of well layers and the barrier layers are positive integers larger than 2, each barrier layer consists of a first barrier layer, a second barrier layer and a third barrier layer, the thickness of the first barrier layer is 0.5-3 nm, and the Si doping concentration is smaller than 1E17cm^-3The thickness of the second barrier layer is 3-14 nm, and the doping concentration of Si is 1E 17-1E 18cm^-3The thickness of the third barrier layer is 0.5-3 nm, and the doping concentration of Si is more than 1E18cm^-3。

Wherein: the buffer layer has a composition of In_aAl_bGa_1-a-bAnd N, wherein a is more than or equal to 0 and less than or equal to 0.2, b is more than or equal to 0 and less than or equal to 1, a + b is more than or equal to 0 and less than or equal to 1, and the thickness is 5-100 nm.

Wherein: the composition of the undoped nitride layer is In_cAl_dGa_1-c-dN, wherein c is more than or equal to 0 and less than or equal to 0.2, d is more than or equal to 0 and less than or equal to 1, c + d is more than or equal to 0 and less than or equal to 1, and the thickness is 1-5 mu m.

Wherein: the component of the n-type nitride layer is In_eAl_fGa_1-e-fN, wherein E is more than or equal to 0 and less than or equal to 0.2, f is more than or equal to 0 and less than or equal to 1, E + f is more than or equal to 0 and less than or equal to 1, the thickness is 1-5 mu m, and the doping concentration of N-type Si is 1E 18-1E 20cm^-3。

Wherein: the composition of the well layer is In_gAl_hGa_1-g-hN, wherein g is more than or equal to 0 and less than or equal to 0.6, h is more than or equal to 0 and less than or equal to 0.6, g + h is more than or equal to 0 and less than or equal to 1, and the thickness is 1-5 nm.

Wherein: the first barrier layer comprises In_iAl_jGa_1-i-jN, wherein i is more than or equal to 0 and less than or equal to 0.2, j is more than or equal to 0 and less than or equal to 1, i + j is more than or equal to 0 and less than or equal to 1, and the second barrier layer comprises the components of In_rAl_xGa_1-r-xN, wherein r is more than or equal to 0 and less than or equal to 0.2, x is more than or equal to 0 and less than or equal to 1, r + x is more than or equal to 0 and less than or equal to 1, and the third barrier layer comprises the components of In_tAl_uGa_1-t-uN, wherein t is more than or equal to 0 and less than or equal to 0.2, u is more than or equal to 0 and less than or equal to 1, and t + u is more than or equal to 0 and less than or equal to 1.

Wherein: the component of the electron blocking layer is In_mAl_nGa_1-m-nN, wherein m is more than or equal to 0 and less than or equal to 0.2, N is more than or equal to 0.1 and less than or equal to 1, m + N is more than or equal to 0.1 and less than or equal to 1, and the thickness is 2-100 nm.

Wherein: the composition of the p-type nitride layer is In_pAl_qGa_1-p-qN, wherein p is more than or equal to 0 and less than or equal toQ is more than or equal to 0 and less than or equal to 1, p + q is more than or equal to 0 and less than or equal to 1, the thickness is 10-200 nm, and the doping concentration of p-type Mg is 5E 18-5E 21cm^-3。

Wherein: the substrate is sapphire (Al)₂O₃) Substrate, silicon (Si) substrate, silicon carbide (SiC) substrate, aluminum nitride (AlN) substrate, gallium nitride (GaN) substrate, gallium oxide (Ga)₂O₃) One of a substrate or a zinc oxide (ZnO) substrate.

(III) advantageous effects

Compared with the prior art, the invention provides a nitride light-emitting diode with high luminous efficiency, which has the following beneficial effects: the barrier layer of the nitride light emitting diode active layer is divided into a first barrier layer, a second barrier layer and a third barrier layer according to different Si doping concentrations, lower Si doping is used for the first barrier layer to obtain low crystal surface roughness, smooth covering of the well layer is achieved, moderate Si doping is used for the second barrier layer to achieve high crystal quality and low resistance value, higher Si doping is used for the third barrier layer to obtain more stress release, and low operating voltage and high light emitting efficiency of the nitride light emitting diode are achieved.

Drawings

Fig. 1 is a schematic view of an epitaxial structure of a nitride light emitting diode according to an embodiment of the present invention.

Fig. 2 is a flowchart of a method for fabricating an epitaxial structure of a nitride light emitting diode according to an embodiment of the present invention.

Reference numerals:

the semiconductor device includes a substrate 100, a buffer layer 200, an undoped nitride layer 300, an n-type nitride layer 400, an active layer 500, a well layer 510, a barrier layer 520, a first barrier layer 521, a second barrier layer 522, a third barrier layer 523, an electron blocking layer 600, and a p-type nitride layer 700.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Embodiment 1, as shown in fig. 1, a nitride light emitting diode with high luminous efficiency includes a substrate 100, and a buffer layer 200, an undoped nitride layer 300, an n-type nitride layer 400, an active layer 500, an electron blocking layer 600, and a p-type nitride layer 700 sequentially disposed on the substrate; wherein: the active layer 500 is a multi-quantum well structure formed by alternately stacking a plurality of well layers 510 and barrier layers 520, the plurality of well layers are positive integers greater than 2, the barrier layers 520 are composed of a first barrier layer 521, a second barrier layer 522 and a third barrier layer 523, the thickness of the first barrier layer 521 is 0.5-3 nm, and the doping concentration of Si is less than 1E17cm^-3The thickness of the second barrier layer 522 is 3-14 nm, and the Si doping concentration is 1E 17-1E 18cm^-3The thickness of the third barrier layer 523 is 0.5-3 nm, and the Si doping concentration is more than 1E18cm^-3。

Specifically, the composition of the buffer layer 200 is In_aAl_bGa_1-a-bN, wherein a is more than or equal to 0 and less than or equal to 0.2, b is more than or equal to 0 and less than or equal to 1, a + b is more than or equal to 0 and less than or equal to 1, and the thickness is 5-100 nm; the composition of the undoped nitride layer 300 is In_cAl_dGa_1-c-dN, wherein c is more than or equal to 0 and less than or equal to 0.2, d is more than or equal to 0 and less than or equal to 1, c + d is more than or equal to 0 and less than or equal to 1, and the thickness is 1-5 mu m; the composition of the n-type nitride layer 400 is In_eAl_fGa_1-e-fN, wherein E is more than or equal to 0 and less than or equal to 0.2, f is more than or equal to 0 and less than or equal to 1, E + f is more than or equal to 0 and less than or equal to 1, the thickness is 1-5 mu m, and the doping concentration of N-type Si is 1E 18-1E 20cm^-3(ii) a The composition of the well layer 510 is In_gAl_hGa_1-g-hN, wherein g is more than or equal to 0 and less than or equal to 0.6, h is more than or equal to 0 and less than or equal to 0.6, g + h is more than or equal to 0 and less than or equal to 1, and the thickness is 1-5 nm; the barrier layer 520 comprises In_iAl_jGa_1-i-jN, wherein i is more than or equal to 0 and less than or equal to 0.2, j is more than or equal to 0 and less than or equal to 1, i + j is more than or equal to 0 and less than or equal to 1, and the thickness is 4-20 nm; the electron blocking layer 600 has a composition of In_mAl_nGa_1-m-nN, wherein m is more than or equal to 0 and less than or equal to 0.2, N is more than or equal to 0.1 and less than or equal to 1, m + N is more than or equal to 0.1 and less than or equal to 1, and the thickness is 2-100 nm; the composition of the p-type nitride layer 700 is In_pAl_qGa_1-p-qN, wherein p is more than or equal to 0 and less than or equal to 0.2, q is more than or equal to 0 and less than or equal to 1, p + q is more than or equal to 0 and less than or equal to 1, the thickness is 10-200 nm, and the doping concentration of p-type Mg is 5E 18-5E 21cm^-3(ii) a The above-mentionedThe substrate 100 is sapphire (Al)₂O₃) Substrate, silicon (Si) substrate, silicon carbide (SiC) substrate, aluminum nitride (AlN) substrate, gallium nitride (GaN) substrate, gallium oxide (Ga)₂O₃) One of a substrate or a zinc oxide (ZnO) substrate.

The following will briefly describe the fabrication process of the nitride light emitting diode shown in fig. 1 by taking a sapphire substrate as an example, and as shown in fig. 2, the specific fabrication process is as follows:

step S1: providing a sapphire substrate 100, putting the sapphire substrate 100 into a cleaning machine for acid cleaning and deionized water flushing in sequence, and finally drying by hot nitrogen;

step S2: putting the sapphire substrate 100 into a magnetron sputtering machine, and depositing a buffer layer 200 with the thickness of 20nm and the component of AlN;

step S3: taking the sapphire substrate 100 out of the magnetron sputtering machine, putting the sapphire substrate into a metal organic chemical vapor deposition Machine (MOCVD), controlling the pressure of a reaction cavity of the MOCVD to be 100-600 torr and the temperature to be 1000-1200 ℃, and introducing quantitative nitrogen, hydrogen, ammonia and trimethyl gallium gas to grow an undoped nitride layer 300 with the thickness of 3 mu m and the component of GaN;

step S4: controlling the pressure of a reaction cavity of the MOCVD to be 200torr and the temperature to be 1000-1200 ℃, introducing quantitative nitrogen, hydrogen, ammonia, silane and trimethyl gallium gas, growing an n-type nitride layer 400 with the thickness of 2 mu m and the component of GaN, wherein the doping concentration of n-type Si is 1E19 cm^-3；

Step S5: adjusting the pressure of a reaction cavity of MOCVD (metal organic chemical vapor deposition) to 200torr and the temperature to 800-1000 ℃, and introducing quantitative nitrogen, hydrogen, ammonia, silane, trimethylindium and triethylgallium gas to sequentially grow a well layer 510 and a barrier layer 520 for 10 periods, wherein the thickness and the components of the well layer 510 are respectively 3nm and In_0.14Ga_0.86The thickness and the components of the N barrier layer 520 and the GaN barrier layer are 10nm and GaN respectively. Wherein barrier layer 520 is comprised of a first barrier layer 521, a second barrier layer 522, and a third barrier layer 523. The thickness of the first barrier layer 521 is 1nm, and the doping concentration of Si is 7E16 cm^-3The thickness of the second barrier layer 522 is 8nm, and the doping concentration of Si is 5E17 cm^-3The thickness of the third barrier layer 523 is 1nm, and the doping concentration of Si is 2E18 cm^-3；

Step S6: changing the pressure of a reaction cavity of MOCVD to 100torr and the temperature to 900-1100 ℃, and introducing quantitative nitrogen, hydrogen, ammonia, trimethylaluminum and trimethylgallium gases, wherein the growth thickness is 20nm, and the component is Al_0.3Ga_0.7An electron blocking layer 600 of N;

step S7: continuously changing the pressure of the reaction cavity of the MOCVD to 500torr at the temperature of 800-1000 ℃, introducing quantitative nitrogen, hydrogen, ammonia, magnesium cyclopentadienyl and trimethyl gallium gas, growing a p-type nitride layer 700 with the thickness of 60nm and the component of GaN, wherein the doping concentration of p-type Mg is 5E19 cm^-3。

According to the invention, the barrier layer of the nitride light-emitting diode active layer is divided into the first barrier layer, the second barrier layer and the third barrier layer according to different Si doping concentrations, the first barrier layer is doped with lower Si to obtain low crystal surface roughness, so that the smooth coverage of the well layer is realized, the second barrier layer is doped with moderate Si to have high crystal quality and low resistance value, and the third barrier layer is doped with higher Si to obtain more stress release, so that the low operating voltage and the high luminous efficiency of the nitride light-emitting diode are realized.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A nitride light-emitting diode with high luminous efficiency comprises a substrate, and a buffer layer, a non-doped nitride layer, an n-type nitride layer, an active layer, an electron blocking layer and a p-type nitride layer which are sequentially arranged on the substrate; the method is characterized in that: the active layer is a multi-quantum well structure formed by alternately stacking a plurality of well layers and barrier layers, the plurality of well layers and barrier layers are positive integers larger than 2, the barrier layers are composed of a first barrier layer, a second barrier layer and a third barrier layer, and the first barrier layer is composed of a first barrier layer, a second barrier layer and a third barrier layerThe barrier layer has a thickness of 0.5-3 nm and a Si doping concentration of less than 1E17cm^-3The thickness of the second barrier layer is 3-14 nm, and the doping concentration of Si is 1E 17-1E 18cm^-3The thickness of the third barrier layer is 0.5-3 nm, and the Si doping concentration is more than 1E18cm^-3。

2. A nitride light emitting diode with high luminous efficiency according to claim 1, wherein: the buffer layer has a composition of In_aAl_bGa_1-a-bAnd N, wherein a is more than or equal to 0 and less than or equal to 0.2, b is more than or equal to 0 and less than or equal to 1, a + b is more than or equal to 0 and less than or equal to 1, and the thickness is 5-100 nm.

3. A nitride light emitting diode with high luminous efficiency according to claim 1, wherein: the composition of the undoped nitride layer is In_cAl_dGa_1-c-dN, wherein c is more than or equal to 0 and less than or equal to 0.2, d is more than or equal to 0 and less than or equal to 1, c + d is more than or equal to 0 and less than or equal to 1, and the thickness is 1-5 mu m.

4. A nitride light emitting diode with high luminous efficiency according to claim 1, wherein: the component of the n-type nitride layer is In_eAl_fGa_1-e-fN, wherein E is more than or equal to 0 and less than or equal to 0.2, f is more than or equal to 0 and less than or equal to 1, E + f is more than or equal to 0 and less than or equal to 1, the thickness is 1-5 mu m, and the doping concentration of N-type Si is 1E 18-1E 20cm^-3。

5. A nitride light emitting diode with high luminous efficiency according to claim 1, wherein: the composition of the well layer is In_gAl_hGa_1-g-hN, wherein g is more than or equal to 0 and less than or equal to 0.6, h is more than or equal to 0 and less than or equal to 0.6, g + h is more than or equal to 0 and less than or equal to 1, and the thickness is 1-5 nm.

6. A nitride light emitting diode with high luminous efficiency according to claim 1, wherein: the first barrier layer comprises In_iAl_jGa_1-i-jN, wherein i is more than or equal to 0 and less than or equal to 0.2, j is more than or equal to 0 and less than or equal to 1, i + j is more than or equal to 0 and less than or equal to 1, and the second barrier layer comprises the components of In_rAl_xGa_1-r-xN, wherein r is more than or equal to 0 and less than or equal to 0.2, x is more than or equal to 0 and less than or equal to 1, and r + x is more than or equal to 0 and less than or equal to 1The third barrier layer comprises In_tAl_uGa_1-t-uN, wherein t is more than or equal to 0 and less than or equal to 0.2, u is more than or equal to 0 and less than or equal to 1, and t + u is more than or equal to 0 and less than or equal to 1.

7. A nitride light emitting diode with high luminous efficiency according to claim 1, wherein: the component of the electron blocking layer is In_mAl_nGa_1-m-nN, wherein m is more than or equal to 0 and less than or equal to 0.2, N is more than or equal to 0.1 and less than or equal to 1, m + N is more than or equal to 0.1 and less than or equal to 1, and the thickness is 2-100 nm.

8. A nitride light emitting diode with high luminous efficiency according to claim 1, wherein: the composition of the p-type nitride layer is In_pAl_qGa_1-p-qN, wherein p is more than or equal to 0 and less than or equal to 0.2, q is more than or equal to 0 and less than or equal to 1, p + q is more than or equal to 0 and less than or equal to 1, the thickness is 10-200 nm, and the doping concentration of p-type Mg is 5E 18-5E 21cm^-3。

9. A nitride light emitting diode with high luminous efficiency according to claim 1, wherein: the substrate is sapphire (Al)₂O₃) Substrate, silicon (Si) substrate, silicon carbide (SiC) substrate, aluminum nitride (AlN) substrate, gallium nitride (GaN) substrate, gallium oxide (Ga)₂O₃) One of a substrate or a zinc oxide (ZnO) substrate.