CN113036600A

CN113036600A - Gallium nitride-based green laser and preparation method thereof

Info

Publication number: CN113036600A
Application number: CN202110241949.0A
Authority: CN
Inventors: 贾传宇
Original assignee: Dongguan University of Technology
Current assignee: Dongguan University of Technology
Priority date: 2021-03-04
Filing date: 2021-03-04
Publication date: 2021-06-25
Anticipated expiration: 2041-03-04
Also published as: AU2021104969A4; CN113036600B

Abstract

The invention discloses a gallium nitride-based green laser and a preparation method thereof. A gallium nitride-based green laser, comprising a gallium nitride single crystal substrate, an n-GaN layer, an n-AlGaN/GaN superlattice confinement layer, a lower waveguide layer, an active region, a p type electron blocking layer, upper waveguide layer, p-AlGaN/GaN superlattice confinement layer, p-GaN contact layer; the active region is a quantum well structure with variable temperature and growth rate, and the lower waveguide layer and the upper waveguide layer are gradients Doped composite waveguide layer. In the present invention, the InGaN/InGaN quantum well structure with variable temperature and growth rate is set as the active region, the gradient-doped u-InGaN+u-GaN+p-GaN+p ⁺ -AlGaN composite upper waveguide layer, and the gradient-doped u-InGaN+u-GaN+p-GaN+p+-AlGaN composite upper waveguide layer. n ⁺ ‑Al _y1 Ga _1‑y1 N+n‑GaN+u‑GaN+u‑In _x5 Ga _1‑x5 N composite lower waveguide layer, which effectively reduces the optical absorption loss of the P-type layer of the laser and improves the quantum efficiency of the laser , further improving the green luminous intensity of the GaN-based green laser.

Description

Gallium nitride-based green laser and preparation method thereof

Technical Field

The invention relates to the technical field of semiconductor photoelectron, in particular to a gallium nitride-based green laser and a preparation method thereof.

Background

Group III-V nitride semiconductor materials, including gallium nitride (GaN), aluminum nitride (AlN) and indium nitride (InN) and their alloys, are third generation semiconductor materials following silicon, gallium arsenide, and are ideal materials for fabricating ultraviolet to green wavelength band semiconductor lasers.

The gallium nitride-based green laser has important application value in the fields of laser display, biomedicine, material processing, optical communication, optical storage, instruments and detection, image recording and the like. The most striking application field of the gallium nitride-based semiconductor laser is laser display at present, and the laser display is a display technology which takes red, green and blue tricolor lasers as light sources, can truly reproduce rich and bright colors of an objective world, and provides more shocking expressive force. With the rapid development of laser display technology, the demand for GaN-based lasers has become more urgent. However, the quantum efficiency of the existing laser is low, so that the luminous intensity is weak, and the service life, reliability and stability of the gallium nitride-based green laser are further influenced.

Chinese patent application CN101937954A discloses an epitaxial growth method for improving the quantum efficiency in a gallium nitride-based light emitting diode, which is to alternately pulse ammonia gas and iii-group metal organic source materials gallium and indium into a growth reaction chamber during the growth of an indium gallium nitride quantum well layer in an active region to form an indium gallium nitride quantum well light emitting layer with high light emitting efficiency. However, the quantum efficiency and the luminous intensity of the gallium nitride-based light emitting diode prepared by the epitaxial growth method still do not meet the actual high requirements.

Therefore, there is a need to develop a gallium nitride-based green laser with higher luminous intensity.

Disclosure of Invention

The invention provides a gallium nitride-based green laser for overcoming the defect of weak luminous intensity in the prior art, which has an InGaN/InGaN quantum well structure with variable temperature and variable growth rate as an active region and a gradient doped u-InGaN + u-GaN + p⁺The AlGaN composite upper waveguide layer structure can effectively reduce the optical absorption loss of a P-type layer of the laser and improve the green light luminous intensity.

The invention also aims to provide a preparation method of the gallium nitride-based green laser.

In order to solve the technical problems, the invention adopts the technical scheme that:

a gallium nitride-based green laser comprises a gallium nitride single crystal substrate, an n-GaN layer, an n-AlGaN/GaN superlattice limiting layer, a lower waveguide layer, an active region, a p-type electron blocking layer, an upper waveguide layer, a p-AlGaN/GaN superlattice limiting layer and a p-GaN contact layer which are sequentially stacked from bottom to top;

the active region is formed by sequentially laminating a first barrier layer, a first temperature-changing layer, a first well layer, a first temperature-changing protective layer, a second barrier layer, a second temperature-changing layer, a second well layer, a second temperature-changing protective layer and a third barrier layer from bottom to top;

the first barrier layer is n⁺GaN, Si doping concentration 10¹⁸～10¹⁹cm^-3，n⁺-the thickness of GaN is 10-15 nm;

the first temperature-changing layer is In_x1Ga_1-x1The temperature changing layer of N, x1 is increased from 0.005-0.01 to 0.25-0.3 In with the increase of the growth thickness_x1Ga_1-x1The total thickness of the N temperature-changing layer is 0.5-1 nm;

the first well layer is In_x2Ga_1-x2The thickness of the N well layer is 1-1.5 nm, and x2 is more than or equal to 0.25 and less than or equal to 0.3;

the first temperature-changing protective layer is In_x3Ga_1-x3The x3 of the N temperature-changing protective layer is reduced from 0.25-0.3 to 0.005-0.01 In along with the increase of the growth thickness_x3Ga_1-x3The total thickness of the N variable temperature protective layer is 0.5-1 nm;

the second barrier layer is u-In_x4Ga_1-x4N, the thickness is 5-10 nm, and x4 is more than or equal to 0.005 and less than or equal to 0.01;

the second temperature-changing layer is In_x5Ga_1-x5The temperature changing layer of N, x5 is increased from 0.005-0.01 to 0.25-0.3 In with the increase of the growth thickness_x5Ga_1-x5The total thickness of the N temperature-changing layer is 0.5-1 nm;

the second well layer is In_x6Ga_1-x6The thickness of the N well layer is 1-1.5 nm, and x6 is more than or equal to 0.25 and less than or equal to 0.3;

the second variable temperature protective layer is In_x7Ga_1-x7The x7 of the N temperature-changing protective layer is reduced from 0.25-0.3 to 0.005-0.01 In along with the increase of the growth thickness_x7Ga_1-x7The total thickness of the N variable temperature protective layer is 0.5-1 nm;

the third barrier layer is non-doped u-AlGaN-In_x8Ga_1-x8The N superlattice structure comprises AlGaN with the thickness of 0.5-1 nm, InGaN with the thickness of 0.5-1 nm, the number of superlattice cycles is 10-20, and x8 is more than or equal to 0.01 and less than or equal to 0.03.

The active region of the invention adopts the stacked barrier layer, the temperature-changing layer, the well layer and the temperature-changing protective layer, so that the overlapping area of an electron hole wave function in the active region of the quantum well can be effectively improved, the quantum efficiency in the quantum well is improved, and the green light luminous intensity is improved.

Preferably, the lower waveguide layer is n⁺-Al_y1Ga_1-y1N+n-GaN+u-GaN+u-In_x9Ga_1-x9Composite lower waveguide layer of N structure with SiH₄As an n-type doping source;

n of the lower waveguide layer⁺-Al_y1Ga_1-y1The thickness of N is 5-15 nm, y1 is more than or equal to 0.05 and less than or equal to 0.15, and N is the same as N⁺Increase in the growth thickness of AlGaN, doping concentration of Si from 10¹⁹～10²⁰cm^-3Down to 10¹⁸～10¹⁹cm^-3；

The thickness of n-GaN in the lower waveguide layer is 50-100 nm, and the doping concentration of Si is from 10 along with the increase of the growth thickness of the n-GaN¹⁸～10¹⁹cm^-3Down to 0;

the thickness of the u-GaN in the lower waveguide layer is 50-100 nm;

u-In the lower waveguide layer_x9Ga_1-x9The thickness of N is 50-100 nm, and x9 is more than or equal to 0.01 and less than or equal to 0.03.

Preferably, the upper waveguide layer is u-In_x10Ga_1-x10N+u-GaN+p-GaN+p⁺-Al_y2Ga_1-y2A composite upper waveguide layer of N structure with Cp₂Mg is used as a p-type doping source;

u-In the upper waveguide layer_x10Ga_1-x10The thickness of N is 50-100 nm, and x10 is more than or equal to 0.01 and less than or equal to 0.03;

the thickness of the u-GaN in the upper waveguide layer is 50-100 nm;

the thickness of p-GaN in the upper waveguide layer is 50-100 nm, and with the increase of the growth thickness of the p-GaN, the doping concentration of Mg is increased from 0 to 10¹⁹cm^-3；

P in the upper waveguide layer⁺-Al_y2Ga_1-y2The thickness of N is 5-15 nm, y2 is more than or equal to 0.05 and less than or equal to 0.15, and p is increased⁺-increase of AlGaN growth thickness with Mg doping concentration from 10¹⁹cm^-3Increased to 10²⁰cm^-3。

In general, the P-type layer has a high Mg doping concentration, the ionization rate of the Mg dopant is low, only less than 10% of Mg atoms are ionized and become free holes, and more than 90% become injection-bound holes, which generate large optical absorption loss. The invention designs gradient doped u-InGaN + u-GaN + p⁺And an AlGaN composite upper waveguide layer structure effectively reduces the optical absorption loss of a laser P-type layer.

Preferably, the p-type electron blocking layer is multi-periodic u-Al_y3Ga_1-y3N/GaN superlattice, y3 is more than or equal to 0.1 and less than or equal to 0.2, the number of superlattice cycles is 10-15, wherein u-Al_y3Ga_1-y3The thickness of N is 2-3 nm, and the thickness of GaN is 2-3 nm.

Preferably, the n-AlGaN/GaN superlattice confinement layer is n-Al_y4Ga_1-y4N/GaN, y4 is more than or equal to 0.05 and less than or equal to 0.15, and SiH₄As an n-type doping source, the doping concentration of Si is 10¹⁸～10¹⁹cm^-3The number of superlattice periods is 100 to 150, wherein n-Al_y4Ga_1-y4The thickness of N is 2.5-3 nm, and the thickness of GaN is 2.5-3 nm.

Preferably, the p-AlGaN/GaN superlattice limiting layer is p-Al_y5Ga_1-y5N/GaN, y5 is more than or equal to 0.05 and less than or equal to 0.15, and Cp₂Mg is used as a p-type doping source, and the doping concentration of Mg is 10¹⁷～10¹⁸cm^-3The number of superlattice periods is 100 to 150, wherein p-Al_y5Ga_1-y5The thickness of N is 2.5-3 nm, and the thickness of GaN is 2.5-3 nm.

Preferably, the thickness of the n-GaN layer is 2-4 mu m, and SiH is used₄As an n-type doping source, the doping concentration of Si is 10¹⁸～10¹⁹cm^-3。

Preferably, the thickness of the p-GaN contact layer is 100-150 nm, and Cp is₂Mg as p-typeA doping source with Mg doping concentration of 10¹⁷～10¹⁸cm^-3。

The invention also provides a preparation method of the active region in the gallium nitride-based green laser, which comprises the following steps:

introducing trimethyl gallium as a group III source and ammonia as a group V source in a nitrogen atmosphere at the temperature of 750-850 ℃, and growing an active region on a lower waveguide layer, wherein the active region is formed by sequentially laminating a first barrier layer, a first temperature changing layer, a first well layer, a first temperature changing protective layer, a second barrier layer, a second temperature changing layer, a second well layer, a second temperature changing protective layer and a third barrier layer from bottom to top;

the growth temperature of the first barrier layer is 850-900 ℃;

the growth rate of the first temperature-changing layer is 0.01-0.02 nm/s, and the growth temperature is reduced to 700-750 ℃ from 800-850 ℃ along with the increase of the growth thickness;

the growth temperature of the first well layer is 700-750 ℃, and the growth rate is 0.01-0.02 nm/s;

the growth rate of the first variable temperature protective layer is 0.03-0.06 nm/s, and the growth temperature is increased from 700-750 ℃ to 800-850 ℃ along with the increase of the growth thickness;

the growth temperature of the second barrier layer is 800-850 ℃, and the growth rate is 0.03-0.06 nm/s;

the growth rate of the second temperature-changing layer is 0.01-0.02 nm/s, and the growth temperature is reduced to 700-750 ℃ from 800-850 ℃ along with the increase of the growth thickness;

the growth temperature of the second well layer is 700-750 ℃, and the growth rate is 0.01-0.02 nm/s;

the growth rate of the second variable temperature protective layer is 0.03-0.06 nm/s, and the growth temperature is increased from 700-750 ℃ to 800-850 ℃ along with the increase of the growth thickness;

the growth temperature of the third barrier layer is 800-850 ℃.

By means of a variable-temperature and variable-speed growth mode, an InGaN/InGaN quantum well structure with gradient In content is epitaxially grown to serve as an active region, the green light emitting performance of the active region can be further improved, and the light emitting intensity of a green laser is improved.

The invention also provides a preparation method of the gallium nitride-based green laser, which comprises the following steps:

s1, performing surface activation treatment on a gallium nitride single crystal substrate in a mixed atmosphere of hydrogen and ammonia at the temperature of 900-1100 ℃;

s2, introducing trimethyl gallium as a group III source, ammonia as a group V source and SiH in a hydrogen atmosphere at the temperature of 950-1200 DEG C₄As an n-type doping source, growing an n-GaN layer on a gallium nitride single crystal substrate;

s3, introducing trimethyl gallium and trimethyl aluminum as a group III source, ammonia as a group V source and SiH in a hydrogen atmosphere at the temperature of 1000-1050 DEG C₄As an n-type doping source, growing an n-AlGaN/GaN superlattice limiting layer on the n-GaN layer;

s4, introducing trimethyl gallium and trimethyl indium as III group sources, ammonia as V group source and SiH in nitrogen atmosphere at 820-850 DEG C₄As an n-type doping source, growing a lower waveguide layer on the n-AlGaN/GaN superlattice limiting layer;

s5, introducing trimethyl gallium as a group III source and ammonia as a group V source in a nitrogen atmosphere at the temperature of 750-850 ℃, and growing an active region on the lower waveguide layer according to the preparation method of the active region;

s6, introducing trimethyl gallium, trimethyl aluminum and trimethyl indium as III group sources, ammonia as V group sources and cyclopentadienyl magnesium as p-type doping sources in a nitrogen atmosphere at 850-1050 ℃, and growing a p-type electron blocking layer on the active region;

s7, in a nitrogen atmosphere, introducing trimethyl gallium and trimethyl indium as III group sources, ammonia as V group sources, and magnesium cyclopentadienyl as p-type doping sources at 820-850 ℃, and growing an upper waveguide layer on the p-type electron barrier layer;

s8, introducing trimethyl gallium, trimethyl aluminum and trimethyl indium as III group sources, ammonia as V group sources and magnesium chloride as p-type doping sources in a hydrogen atmosphere at 850-1050 ℃, and growing a p-AlGaN/GaN superlattice limiting layer on the upper waveguide layer;

and S9, introducing trimethyl gallium as a group III source, ammonia as a group V source, magnesium dicumyl as a p-type doping source, and growing a p-GaN contact layer on the p-AlGaN/GaN superlattice limiting layer to obtain the gallium nitride-based green laser at the temperature of 950-980 ℃ in a hydrogen atmosphere.

And S9, after the growth is finished, annealing for 5-20 min in a pure nitrogen atmosphere at the temperature of 700-750 ℃, then cooling to room temperature, and finishing the growth.

Preferably, steps S1 to S9 are performed in a metal organic compound vapor phase epitaxy reaction chamber.

Preferably, S1, heating to 500-700 ℃ in a hydrogen atmosphere, introducing ammonia gas to form a hydrogen and ammonia gas mixed atmosphere, heating to 900-1100 ℃, and carrying out surface activation treatment on the GaN single crystal substrate. In the step S1, the time for carrying out surface activation treatment on the GaN single crystal substrate can be 1-15 min.

Compared with the prior art, the invention has the beneficial effects that:

the invention creatively develops a gallium nitride-based green laser with high luminous intensity. Gradient doped u-InGaN + u-GaN + p by setting InGaN/InGaN quantum well structure with gradient In content and growing at variable temperature and variable growth rate as active region⁺-an AlGaN composite upper waveguide layer, and gradient doped n⁺-Al_y1Ga_1-y1N+n-GaN+u-GaN+u-In_x5Ga_1-x5The N composite lower waveguide layer effectively reduces the optical absorption loss of a P-type layer of the laser and improves the quantum efficiency, thereby improving the green light luminous intensity of the gallium nitride-based green laser.

Drawings

Fig. 1 is a schematic structural diagram of a gallium nitride-based green laser according to the present invention.

Fig. 2 shows the pumping result of the gan-based green laser according to embodiment 1 of the present invention.

Fig. 3 shows the pumping result of the gan-based green laser according to embodiment 2 of the present invention.

Fig. 4 shows the result of optical pumping of the gallium nitride-based green laser of comparative example 1 according to the present invention.

Detailed Description

The present invention will be further described with reference to the following embodiments.

The raw materials in the examples are all commercially available;

the example preparation process of the present application uses the Aixtron corporation, a tightly coupled vertical reactor MOCVD growth system.

Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.

Example 1

The present embodiment provides a gallium nitride-based green laser, as shown in fig. 1, which includes a gallium nitride single crystal substrate 101, an n-GaN layer 102, an n-AlGaN/GaN superlattice confinement layer 103, a lower waveguide layer 104, an active region 105, a p-type electron blocking layer 106, an upper waveguide layer 107, a p-AlGaN/GaN superlattice confinement layer 108, and a p-GaN contact layer 109, which are sequentially stacked from bottom to top.

The gallium nitride-based green laser is prepared by the following steps:

s1, firstly, heating to 500-700 ℃ in a hydrogen atmosphere in a metal organic compound vapor phase epitaxy reaction chamber, then introducing ammonia gas to form a hydrogen and ammonia gas mixed atmosphere, heating to 900-1100 ℃, and carrying out surface activation treatment on a GaN single crystal substrate for 3-15 min.

S2, introducing trimethyl gallium as a group III source, ammonia as a group V source and SiH in a hydrogen atmosphere at the temperature of 950-1200 DEG C₄As an n-type doping source, an n-GaN layer with a thickness of 2 μm and a Si doping concentration of 10 was grown on a gallium nitride single crystal substrate¹⁸cm^-3。

S3, introducing trimethyl gallium and trimethyl aluminum as a group III source, ammonia as a group V source and SiH in a hydrogen atmosphere at the temperature of 1000-1050 DEG C₄As an n-type doping source, growing n-Al on the n-GaN layer_0.05Ga_0.95N/GaN superlattice confinement layer with Si doping concentration of 10¹⁸cm^-3The number of superlattice periods is 100, wherein n-Al_0.05Ga_0.95The thickness of both N and GaN was 2.5 nm.

S4. in nitrogen atmosphere, the temperature is 820 &Introducing trimethyl gallium and trimethyl indium as III group source, ammonia as V group source, SiH at 850 deg.C₄As an n-type doping source, growing a lower waveguide layer on the n-AlGaN/GaN superlattice limiting layer;

the lower waveguide layer is n⁺-Al_0.05Ga_0.95N+n-GaN+u-GaN+u-In_0.01Ga_0.99Composite lower waveguide layer of N structure with SiH₄As an n-type doping source;

n of the lower waveguide layer⁺-Al_0.05Ga_0.95The thickness of N is 5nm, with N⁺Increase in the growth thickness of AlGaN, doping concentration of Si from 10¹⁹cm^-3Down to 10¹⁸cm^-3；

The thickness of n-GaN in the lower waveguide layer is 50nm, and the doping concentration of Si is 10 along with the increase of the growth thickness of n-GaN¹⁸cm^-3Down to 0;

the thickness of u-GaN in the lower waveguide layer is 50 nm;

u-In the lower waveguide layer_0.01Ga_0.99The thickness of N was 50 nm.

S5, introducing trimethyl gallium serving as a group III source and ammonia serving as a group V source in a nitrogen atmosphere at the temperature of 750-850 ℃, and growing an active region on the lower waveguide layer;

the first barrier layer is heavily doped n⁺GaN, Si doping concentration 10¹⁸cm^-3，n⁺-the thickness of GaN is 10nm and the growth temperature is 850 ℃;

the first temperature-changing layer is In with the thickness of 0.5nm_x1Ga_1-x1The growth rate of the N temperature-changing layer is 0.01nm/s, the growth temperature is reduced from 800 ℃ to 700 ℃, and x1 is increased from 0.005 to 0.25 along with the increase of the growth thickness;

the first well layer is In_0.25Ga_0.75An N well layer with thickness of 1.5nm and growth temperature of 700 deg.C and growth rateIs 0.01 nm/s;

the first temperature-changing protective layer is In with the thickness of 0.5nm_x3Ga_1-x3The growth temperature of the N variable temperature protective layer is increased from 700 ℃ to 800 ℃, the growth rate is 0.03nm/s, and x3 is reduced from 0.25 to 0.005 along with the increase of the growth thickness;

the second barrier layer is u-In_0.005Ga_0.995N, the thickness is 5nm, the growth temperature is 800 ℃, and the growth rate is 0.03 nm/s;

the second temperature-changing layer is In with the thickness of 0.5nm_x5Ga_1-x5The growth rate of the N temperature-changing layer is 0.01nm/s, the growth temperature is reduced from 800 ℃ to 700 ℃, and x5 is increased from 0.005 to 0.25 along with the increase of the growth thickness;

the second well layer is In_0.25Ga_0.75An N well layer with the thickness of 1.5nm and the growth temperature of 700 ℃;

the second variable temperature protective layer is In with the thickness of 0.5nm_x7Ga_1-x7The growth temperature of the N variable temperature protective layer is increased from 700-750 ℃ to 800-850 ℃, the growth rate is 0.03-0.06 nm/s, and x7 is reduced from 0.25 to 0.005 along with the increase of the growth thickness;

the third barrier layer is non-doped u-AlGaN/In_0.01Ga_0.99A N superlattice structure with a growth temperature of 800 deg.C, AlGaN thickness of 0.5nm, In_0.01Ga_0.99The N thickness was 0.5nm and the number of superlattice periods was 10.

S6, introducing trimethyl gallium, trimethyl aluminum and trimethyl indium as III group sources, ammonia as V group sources and cyclopentadienyl magnesium as p-type doping sources in a nitrogen atmosphere at 850-1050 ℃, and growing a p-type electron blocking layer on the active region; the p-type electron blocking layer is multi-period u-Al_0.1Ga_0.99N/GaN superlattice with a superlattice period of 10, wherein u-Al_0.1Ga_0.99The thickness of N is 2nm, and the thickness of GaN is 2 nm.

upper waveguide layerIs u-In_0.01Ga_0.99N+u-GaN+p-GaN+p⁺-Al_0.05Ga_0.95A composite upper waveguide layer of N structure with Cp₂Mg is used as a p-type doping source;

u-I in the upper waveguide layer_0.01Ga_0.99The thickness of N is 50 nm;

the thickness of u-GaN in the upper waveguide layer is 50 nm;

the thickness of p-GaN in the upper waveguide layer is 50nm, and the doping concentration of Mg is increased from 0 to 10 along with the increase of the growth thickness of the p-GaN¹⁹cm^-3；

P in the upper waveguide layer⁺-Al_0.05Ga_0.95Thickness of N5 nm with p⁺-increase of AlGaN growth thickness with Mg doping concentration from 10¹⁹cm^-3Increased to 10²⁰cm^-3。

S8, introducing trimethyl gallium, trimethyl aluminum and trimethyl indium as III group sources, ammonia as V group sources, and magnesium chloride as p-type doping source in a hydrogen atmosphere at 850-1050 ℃, and growing p-Al on the upper waveguide layer_0.05Ga_0.95N/GaN superlattice confinement layer with Cp₂Mg is used as a p-type doping source, and the doping concentration of Mg is 10¹⁷cm^-3The number of superlattice periods is 100, wherein p-Al_0.05Ga_0.95The thickness of N is 2.5nm, and the thickness of GaN is 2.5 nm.

S9, introducing trimethyl gallium as a group III source, ammonia as a group V source, magnesium dicumyl as a p-type doping source in a hydrogen atmosphere at the temperature of 950-980 ℃, growing a p-GaN contact layer on the p-AlGaN/GaN superlattice limiting layer, wherein the thickness of the p-GaN contact layer is 100nm, and the Mg doping concentration is 10¹⁷cm^-3；

And annealing for 5-20 min at 700-750 ℃ in a pure nitrogen atmosphere, cooling to room temperature, and finishing growth to obtain the gallium nitride-based green laser.

Example 2

The gallium nitride-based green laser is prepared by the following steps:

S2, introducing trimethyl gallium as a group III source, ammonia as a group V source and SiH in a hydrogen atmosphere at the temperature of 950-1200 DEG C₄As an n-type doping source, an n-GaN layer with a thickness of 4 μm and a Si doping concentration of 10 was grown on a gallium nitride single crystal substrate¹⁹cm^-3。

S3, introducing trimethyl gallium and trimethyl aluminum as a group III source, ammonia as a group V source and SiH in a hydrogen atmosphere at the temperature of 1000-1050 DEG C₄As an n-type doping source, growing n-Al on the n-GaN layer_0.15Ga_0.85N/GaN superlattice confinement layer with Si doping concentration of 10¹⁹cm^-3The number of superlattice periods is 150, wherein n-Al_0.15Ga_0.85The thickness of N is 3nm, and the thickness of GaN is 3 nm.

the lower waveguide layer is n⁺-Al_0.15Ga_0.85N+n-GaN+u-GaN+u-In_0.03Ga_0.97Composite lower waveguide layer of N structure with SiH₄As an n-type doping source;

n of the lower waveguide layer⁺-Al_0.15Ga_0.85The thickness of N is 15nm, with N⁺Increase in the growth thickness of AlGaN, doping concentration of Si from 10²⁰cm^-3Down to 10¹⁹cm^-3；

The thickness of n-GaN in the lower waveguide layer is 100nm, and the doping concentration of Si is 10 along with the increase of the growth thickness of n-GaN¹⁹cm^-3Down to 0;

the thickness of u-GaN in the lower waveguide layer is 100 nm;

u-In the lower waveguide layer_0.03Ga_0.97The thickness of N was 100 nm.

the first barrier layer is heavily doped n⁺GaN, Si doping concentration 10¹⁹cm^-3，n⁺-the thickness of GaN is 15nm and the growth temperature is 900 ℃;

the first temperature-changing layer is In with the thickness of 1nm_x1Ga_1-x1The growth rate of the N temperature-changing layer is 0.02nm/s, the growth temperature is reduced from 850 ℃ to 750 ℃, and the x1 is increased from 0.01 to 0.3 along with the increase of the growth thickness;

the first well layer is In_0.03Ga_0.97The thickness of the N well layer is 1.5nm, the growth temperature is 700 ℃, and the growth rate is 0.02 nm/s;

the first temperature-changing protective layer is In with the thickness of 1nm_x3Ga_1-x3The growth temperature of the N variable temperature protective layer is increased from 750 ℃ to 850 ℃, the growth rate is 0.06nm/s, and x3 is reduced from 0.3 to 0.01 along with the increase of the growth thickness;

the second barrier layer is u-In_0.01Ga_0.99N, the thickness is 10nm, the growth temperature is 850 ℃, and the growth rate is 0.06 nm/s;

the second temperature-changing layer is In with the thickness of 1nm_x5Ga_1-x5The growth rate of the N temperature-changing layer is 0.02nm/s, the growth temperature is reduced from 850 ℃ to 750 ℃, and the x5 is increased from 0.01 to 0.3 along with the increase of the growth thickness;

the second well layer is In_0.3Ga_0.7An N well layer with the thickness of 1nm and the growth temperature of 700 ℃;

the second variable temperature protective layer is In with the thickness of 1nm_x7Ga_1-x7The growth temperature of the N variable temperature protective layer is increased from 750 ℃ to 850 ℃, the growth rate is 0.06nm/s, and x7 is reduced from 0.3 to 0.01 along with the increase of the growth thickness;

the third barrier layer is non-doped u-AlGaN/In_0.03Ga_0.97The growth temperature of the N superlattice structure is 850 ℃, wherein the thickness of AlGaN is 1nm, In_0.03Ga_0.97N thickness is 1nm and the number of superlattice periods is 20.

S6, introducing trimethyl gallium, trimethyl aluminum and trimethyl indium as III group sources, ammonia as V group sources and cyclopentadienyl magnesium as p-type doping sources in a nitrogen atmosphere at 850-1050 ℃, and growing a p-type electron blocking layer on the active region; the p-type electron blocking layer is multi-period u-Al_0.2Ga_0.8N/GaN superlattice with a superlattice period of 15, wherein u-Al_0.2Ga_0.8The thickness of N is 3nm, and the thickness of GaN is 3 nm.

the upper waveguide layer is u-In_0.03Ga_0.97N+u-GaN+p-GaN+p⁺-Al_0.15Ga_0.75A composite upper waveguide layer of N structure with Cp₂Mg is used as a p-type doping source;

u-In the upper waveguide layer_x6Ga_1-x6The thickness of N is 100 nm;

the thickness of u-GaN in the upper waveguide layer is 100 nm;

the thickness of p-GaN in the upper waveguide layer is 100nm, and the doping concentration of Mg is increased from 0 to 10 along with the increase of the growth thickness of the p-GaN¹⁹cm^-3；

P in the upper waveguide layer⁺-Al_0.15Ga_0.75The thickness of N is 15nm with p⁺Increase in AlGaN growth thickness, doping of MgImpurity concentration is from 10¹⁹cm^-3Increased to 10²⁰cm^-3。

S8, introducing trimethyl gallium, trimethyl aluminum and trimethyl indium as III group sources, ammonia as V group sources, and magnesium chloride as p-type doping source in a hydrogen atmosphere at 850-1050 ℃, and growing p-Al on the upper waveguide layer_0.15Ga_0.85N/GaN superlattice confinement layer with Cp₂Mg is used as a p-type doping source, and the doping concentration of Mg is 10¹⁸cm^-3The number of superlattice periods is 150, wherein p-Al_0.15Ga_0.85The thickness of N is 3nm, and the thickness of GaN is 3 nm.

S9, introducing trimethyl gallium as a group III source, ammonia as a group V source, magnesium dicumyl as a p-type doping source in a hydrogen atmosphere at the temperature of 950-980 ℃, growing a p-GaN contact layer on the p-AlGaN/GaN superlattice limiting layer, wherein the thickness of the p-GaN contact layer is 150nm, and the Mg doping concentration is 10¹⁸cm^-3；

Comparative example 1

The comparison example provides a gallium nitride-based green laser, which comprises a gallium nitride single crystal substrate, an n-GaN layer, an n-AlGaN/GaN superlattice limiting layer, a lower waveguide layer, an active region, a p-type electron blocking layer, an upper waveguide layer, a p-AlGaN/GaN superlattice limiting layer and a p-GaN contact layer which are sequentially stacked from bottom to top.

The gallium nitride-based green laser differs from embodiment 1 in that:

the preparation method of the lower waveguide layer comprises the following steps:

introducing trimethyl gallium and trimethyl indium as III group sources and ammonia as V group sources in a nitrogen atmosphere at 820-850 ℃, and growing a lower waveguide layer on the n-AlGaN/GaN superlattice limiting layer;

the lower waveguide layer is an undoped GaN waveguide layer, the thickness is 155nm, and the growth temperature is 850-900 ℃.

The preparation method of the active region comprises the following steps:

introducing trimethyl gallium as a group III source and ammonia as a group V source in a nitrogen atmosphere at the temperature of 750-850 ℃, and growing an active region on the lower waveguide layer;

the active region adopts In_0.25Ga_0.75N/GaN double quantum well structure with active region In_0.25Ga_0.75The N well layer grows at the constant temperature of 750-800 ℃, the thickness of the N well layer is 2.5nm, the total thickness of GaN in the middle barrier layer is 10nm, and the GaN barrier layer grows at the constant temperature of 850-900 ℃.

The preparation method of the upper waveguide layer comprises the following steps:

introducing trimethyl gallium and trimethyl indium as III group sources, ammonia as V group sources and cyclopentadienyl magnesium as p-type doping sources in a nitrogen atmosphere at 820-850 ℃, and growing an upper waveguide layer on the p-type electron blocking layer; the upper waveguide layer is a u-GaN waveguide layer, the thickness is 100nm, and the growth temperature is 800-850 ℃.

Other structural parameters of this comparative example were the same as those of example 1.

Performance testing

Performing optical pump lasing on the GaN-based light-filtering laser, adopting a 355nm short-wavelength violet laser as a pumping source, and injecting light with the power density of 2KW/cm²The light pumping results under the conditions of (1) were as follows:

the pumping result of the gan-based green laser in example 1 is shown in fig. 2, and the laser epitaxial material is rapidly detected by a laser pumping method, and the detection result is as follows: the optical pump lases at a wavelength of 520 nm.

The pumping result of the gan-based green laser of embodiment 2 is shown in fig. 3, and the laser epitaxial material is rapidly detected by a laser pumping method, and the detection result is as follows: the optical pump lases at a wavelength of 530 nm.

The pumping result of the gan-based green laser of the comparative example 1 is shown in fig. 4, and the laser epitaxial material is rapidly detected by a laser pumping method, and the detection result is as follows: the optical pump lases at a wavelength of 520 nm.

By comparing the data of the light pump lasing detection in the embodiments 1 and 2 and the data of the light pump lasing detection in the comparative example 1 under the condition of the same light power injection density, the gallium nitride-based green laser prepared by the solutions in the embodiments 1 and 2 has larger output light power, and by adopting the technical solution of the present invention, the quantum efficiency in the laser can be improved, and higher green light emission intensity can be obtained.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A gallium nitride-based green laser, characterized in that it comprises a gallium nitride single crystal substrate, an n-GaN layer, an n-AlGaN/GaN superlattice confinement layer, an Waveguide layer, active region, p-type electron blocking layer, upper waveguide layer, p-AlGaN/GaN superlattice confinement layer, p-GaN contact layer;

The active region is a first barrier layer, a first temperature change layer, a first well layer, a first temperature change protective layer, a second barrier layer, a second temperature change layer, a second well layer, The second temperature-changing protective layer and the third barrier layer;

The first barrier layer is n ⁺ -GaN, the Si doping concentration is 10 ¹⁸ -10 ¹⁹ cm ^-3 , and the thickness of n ⁺ -GaN is 10 - 15 nm;

The first temperature change layer is an In _x1 Ga _1-x1 N temperature change layer. With the increase of the growth thickness, x1 increases from 0.005 to 0.01 to 0.25 to 0.3, and the total thickness of the In _x1 Ga _1-x1 N temperature change layer is 0.5 to 1 nm. ;

The first well layer is an In _x2 Ga _1-x2 N well layer, with a thickness of 1-1.5 nm, and 0.25≤x2≤0.3;

The first temperature-variable protective layer is an In _x3 Ga _1-x3 N temperature-variable protective layer, and as the growth thickness increases, x3 decreases from 0.25 to 0.3 to 0.005 to 0.01, and the total thickness of the In _x3 Ga _1-x3 N temperature-variable protective layer is 0.5～1nm;

The second barrier layer is u-In _x4 Ga _1-x4 N, with a thickness of 5-10 nm, and 0.005≤x4≤0.01;

The second temperature change layer is an In _x5 Ga _1-x5 N temperature change layer, and as the growth thickness increases, x5 increases from 0.005 to 0.01 to 0.25 to 0.3, and the total thickness of the In _x5 Ga _1-x5 N temperature change layer is 0.5 to 1 nm. ;

The second well layer is an In _x6 Ga _1-x6 N well layer, with a thickness of 1-1.5 nm, and 0.25≤x6≤0.3;

The second temperature-variable protective layer is an In _x7 Ga _1-x7 N temperature-variable protective layer, and as the growth thickness increases, x7 decreases from 0.25 to 0.3 to 0.005 to 0.01, and the total thickness of the In _x7 Ga _1-x7 N temperature-variable protective layer is 0.5～1nm;

The third barrier layer is an undoped u-AlGaN/In _x8 Ga _1-x8 N superlattice structure, wherein the thickness of AlGaN is 0.5-1 nm, the thickness of InGaN is 0.5-1 nm, and the number of superlattice periods is 10-20 , 0.01≤x8≤0.03.

2. The gallium nitride-based green laser according to claim 1, wherein the lower waveguide layer is n ⁺ -Al _y1 Ga _1- _y1 N+n-GaN+u-GaN+u-In _x9 Ga The composite lower waveguide layer of the _1-x9 N structure, with SiH ₄ as the n-type doping source;

The thickness of n ⁺ -Al _y1 Ga _1-y1 N in the lower waveguide layer is 5-15 nm, 0.05≤y1≤0.15, with the increase of the growth thickness of n ⁺ -AlGaN, the doping concentration of Si is from 10 ¹⁹ to 10 ²⁰ cm ^-3 decreased to 10 ¹⁸ ~ 10 ¹⁹ cm ^-3 ;

The thickness of n-GaN in the lower waveguide layer is 50-100 nm, and the doping concentration of Si decreases from 10 ¹⁸ to 10 ¹⁹ cm ^-3 to 0 as the growth thickness of n-GaN increases;

The thickness of u-GaN in the lower waveguide layer is 50-100 nm;

The thickness of u-In _x9 Ga _1-x9 N in the lower waveguide layer is 50-100 nm, and 0.01≤x9≤0.03.

3. The gallium nitride-based green laser according to claim 2, wherein the upper waveguide layer is u- _Inx10Ga1 _-x10N +u-GaN+p-GaN+p ⁺ -Al _y2Ga The composite upper waveguide layer of _1-y2N structure uses Cp ₂ Mg as the p-type doping source;

The thickness of u-In _x10 Ga _1-x10 N in the upper waveguide layer is 50-100 nm, 0.01≤x10≤0.03;

The thickness of u-GaN in the upper waveguide layer is 50-100 nm;

The thickness of p-GaN in the upper waveguide layer is 50-100 nm, and the doping concentration of Mg increases from 0 to 10 ¹⁹ cm ^-3 as the growth thickness of p-GaN increases;

The thickness of p ⁺ -Al _y2 Ga _1-y2 N in the upper waveguide layer is 5-15 nm, 0.05≤y2≤0.15, with the increase of the growth thickness of p ⁺ -AlGaN, the doping concentration of Mg increases from 10 ¹⁹ cm ^{- 3} to 10 ²⁰ cm ^-3 .

4. The gallium nitride-based green laser according to claim 3, wherein the p-type electron blocking layer is a multi-period u-Al _y3 Ga _1-y3 N/GaN superlattice, 0.1≤y3≤ 0.2, the number of superlattice periods is 10-15, wherein the thickness of u- _Aly3Ga1 _-y3N is 2-3nm, and the thickness of GaN is 2-3nm.

5. The gallium nitride-based green laser according to claim 4, wherein the n-AlGaN/GaN superlattice confinement layer is n-Al _y4 Ga _1-y4 N/GaN, 0.05≤y4≤0.15 , using SiH ₄ as the n-type doping source, the Si doping concentration is 10 ¹⁸ ～ 10 ¹⁹ cm ^-3 , the number of superlattice periods is 100 ～ 150, and the thickness of n-Al _y4 Ga _1-y4 N is 2.5 ～ 3nm , GaN thickness is 2.5 ~ 3nm.

6. The gallium nitride-based green laser according to claim 5, wherein the p-AlGaN/GaN superlattice confinement layer is p-Al _y5 Ga _1-y5 N/GaN, 0.05≤y5≤0.15 , with Cp ₂ Mg as the p-type doping source, the Mg doping concentration is 10 ¹⁷ ～ 10 ¹⁸ cm ^-3 , the number of superlattice periods is 100～150, and the thickness of p-Al _y5 Ga _1-y5 N is 2.5～ 3nm, GaN thickness is 2.5-3nm.

7 . The GaN-based green laser according to claim 6 , wherein the thickness of the n-GaN layer is 2-4 μm, SiH ₄ is used as the n-type doping source, and the Si doping concentration is 10 ¹⁸ . ~10 ¹⁹ cm ^-3 .

8 . The GaN-based green laser according to claim 7 , wherein the thickness of the p-GaN contact layer is 100-150 nm, Cp ₂ Mg is used as the p-type doping source, and the Mg doping concentration is 10 ¹⁷ - 10 ¹⁸ cm ^-3 .

9. The method for preparing an active region in a gallium nitride-based green laser according to any one of claims 1 to 8, characterized in that it comprises the following steps:

In a nitrogen atmosphere at a temperature of 750-850°C, the active region is grown on the lower waveguide layer by feeding trimethylgallium as the III group source and ammonia gas as the V group source, and the active region is from bottom to top A first barrier layer, a first temperature-changing layer, a first well layer, a first temperature-changing protective layer, a second barrier layer, a second temperature-changing layer, a second well layer, a second temperature-changing protective layer, and a third barrier layer, which are stacked in sequence ;

The growth temperature of the first barrier layer is 850-900°C; the growth rate of the first temperature-changing layer is 0.01-0.02nm/s, and the growth temperature decreases from 800-850°C to 700-750°C with the increase of the growth thickness; the first The growth temperature of the well layer is 700～750℃, and the growth rate is 0.01～0.02nm/s; the growth rate of the first temperature-changing protective layer is 0.03～0.06nm/s, and the growth temperature is increased from 700～750℃ with the increase of the growth thickness. Rise to 800～850℃; the growth temperature of the second barrier layer is 800～850℃, and the growth rate is 0.03～0.06nm/s; the growth rate of the second variable temperature layer is 0.01～0.02nm/s, and the growth temperature increases with the growth The thickness increases from 800-850°C to 700-750°C; the growth temperature of the second well layer is 700-750°C, and the growth rate is 0.01-0.02 nm/s; the growth rate of the second temperature-varying protective layer is 0.03-0.06 nm/s, the growth temperature increases from 700-750℃ to 800-850℃ with the increase of the growth thickness; the growth temperature of the third barrier layer is 800-850℃.

10 . The preparation method according to claim 9 , wherein the growth of the active region is performed in a metal organic compound vapor phase epitaxy reaction chamber. 11 .