WO2017041662A1

WO2017041662A1 - Gallium nitride-based laser diode and manufacturing method thereof

Info

Publication number: WO2017041662A1
Application number: PCT/CN2016/097755
Authority: WO
Inventors: 冯向旭; 张洁; 叶孟欣; 刘建明; 徐宸科
Original assignee: 厦门市三安光电科技有限公司
Priority date: 2015-09-11
Filing date: 2016-09-01
Publication date: 2017-03-16
Also published as: CN105048286A

Abstract

A gallium nitride-based laser diode and a manufacturing method thereof. The laser diode comprises: a substrate (1), an n-type layer (2), an n-type limiting layer, an n-type waveguide layer (4), an active layer (5), a p-type waveguide layer (6), a p-type limiting layer (7) and a p-type layer (8), wherein the n-type limiting layer comprises a stacked structure consisting of a first n-type limiting layer (31) and a second n-type limiting layer (32). Using the AlN/AlGaN superlattice as the bottom layer of the n-type limiting layer, the Al component of the n-type limiting layer can be effectively improved, and the lasing threshold of a laser can be lowered; epitaxial layer can be effectively prevented from cracking, and the product yield improved.

Description

Inventive name: gallium nitride based laser diode and preparation method thereof

[0001] The present invention relates to the field of semiconductor optoelectronic device fabrication, and more particularly to a gallium nitride-based laser diode and a method of fabricating the same.

Background technique

[0002] Laser diodes (LDs) have attracted much attention in terms of collimation, light purity, etc., and have irreplaceable applications in many technical fields. In particular, LD based on gallium nitride material has become an important direction for the development of LD because its wavelength range theoretically covers the entire visible light band and ultraviolet band. Gallium nitride materials Blue and green LD technology has made great progress in research, but its application is also plagued by difficulties in preparation and not widely used. Especially the green LD, the lasing of its electric injection has not yet been realized in China. At present, the luminous efficiency of LD is relatively low, and electro-lasering is difficult. From the epitaxial structure, it is very important to further increase the LD limiting layer A1 composition to lower the excitation threshold.

[0003] A conventional laser diode confinement layer is an AlGaN layer. In order to achieve lasing at longer wavelengths, this n-type A1G aN layer requires a higher A1 composition or thicker to achieve better light confinement. When the A1 component is high or the thickness is too thick, the epitaxial film will be cleaved. In addition, since the epitaxial layer is grown on the GaN layer, the stress limits the incorporation efficiency of A1, making the confinement layer of the higher A1 component more difficult to obtain.

technical problem

Problem solution

Technical solution

In view of the deficiencies of the prior art, an object of the present invention is to provide a gallium nitride-based laser diode and a method of fabricating the same.

In order to solve the above technical problem, a technical solution adopted by the present invention is: Providing a gallium nitride laser diode structure, comprising: a substrate, an n-type layer, an n-type confinement layer, an n-type waveguide layer, and an active layer And a p-type waveguide layer, a p-type confinement layer, and a p-type layer, wherein: the n-type confinement layer comprises a stacked structure of a first n-type confinement layer and a second n-type confinement layer.

[0006] Preferably, the first n-type confinement layer is A1N, the second n-type confinement layer is AlGaN, and the stacked structure is a superlattice structure. [0007] Preferably, the first n-type confinement layer is an AlN/AlGaN superlattice structure, and the second n-type confinement layer is AlGaN.

[0008] Preferably, the Al composition of AlGaN in the superlattice structure is not higher than 20%.

[0009] Preferably, the thickness of the AlGaN in the superlattice structure is 10 to 30 persons, and the thickness of the A1N is 2 to 10 persons.

[0010] Preferably, the number of cycles of the superlattice structure is 10~30.

[0011] Preferably, the laser diode emits light in a blue to green light wavelength range.

[0012] In order to solve the above technical problem, another technical solution adopted by the present invention is: Providing a method for preparing a gallium nitride-based laser diode, the process steps comprising: forming an n-type layer over a substrate; Forming an n-type confinement layer on the n-type layer, the n-type confinement layer comprising a stacked structure of a first n-type confinement layer and a second n-type confinement layer; forming an n-type waveguide layer on the n-type confinement layer; Forming a multi-quantum well active layer on the n-type waveguide layer; forming a p-type waveguide layer on the active layer; forming a p-type confinement layer on the p-type waveguide layer; and the p-type confinement layer A p-type layer is formed thereon.

[0013] Preferably, the first n-type confinement layer is A1N, the second n-type confinement layer is AlGaN, and the stacked structure is a superlattice structure.

[0014] Preferably, the first n-type confinement layer is an AlN/AlGaN superlattice structure, and the second n-type confinement layer is AlGaN.

[0015] The present invention has at least the following beneficial effects: (1) By improving the design of the n-type confinement layer, introducing an AlN/AlGaN superlattice structure in the n-type confinement layer can effectively improve the A1 component in the n-type confinement layer. , reducing the lasing threshold, thus making it easier to achieve the lasing of the green laser; (2) using the AlN/AlGaN superlattice as the underlying structure of the n-type confinement layer, can effectively prevent the subsequent epitaxial layer (especially the n-type confinement layer) The splitting can greatly improve the yield.

Advantageous effects of the invention

Brief description of the drawing

DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are intended to be a part of the description of the invention. In addition, the drawing figures are a summary of the description and are not drawn to scale.

1 is a side view of a nitride laser diode of the present invention. 2 is a schematic view showing the structure of an AlN/AlGaN superlattice in FIG. 1.

[0019] The reference numerals in the figures are as follows: 1. substrate; 2. n-type layer; 31. first n-type limiting layer;

AlGaN layer; 312. A1N layer; 32. Second n-type confinement layer; 4. n-type waveguide layer; 5. Active layer; 51. Quantum well; 52. Quantum barrier; 6. P-type waveguide layer; Type limiting layer; 8. p type layer; 9. p type contact layer.

Embodiments of the invention

[0020] Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Referring to FIG. 1, a gallium nitride-based laser diode generally includes: a substrate 1, an n-type layer 2, a first n-type confinement layer 31, and a second n-type confinement layer 32, from bottom to top. The n-type waveguide layer 4, the multiple quantum well active layer 5, the p-type waveguide layer 6, the p-type confinement layer 7, the p-type layer 8, and the p-type contact layer 9, the laser diode emits light in the blue to green wavelength band.

[0022] Specifically, the material of the substrate 1 may be selected from an alumina single crystal (Sapphire;), SiC (6H-SiC or 4H-SiC), Si, GaAs, GaN substrate or a lattice constant close to a nitride semiconductor. Single crystal oxide.

[0023] The material of the n-type layer 2 is aluminum gallium indium nitride (A _X — _y Ga _x In _y N), where 0≤X< 1, 0≤Y< 1 =

[0024] The n-type confinement layer includes a stacked structure of the first n-type confinement layer 31 and the second n-type confinement layer 32. Η-type confinement layer 31 of the first material is eight ^ / eight 1 ₁ - ^ & superlattice, wherein 0 <Χ <0.2, i.e., components of AlGaN A1 not higher than 20 _<¾!. Shown, A1N / A ^ & ^ superlattice eight in FIG. 2 1 ₁ _{_-!!} ^ & ^ Layer 311 thickness 15, the thickness of the A1N layer 312 is 5, a superlattice of 20 cycles. The material of the second n-type confinement layer 32 is A _x Ga _x N, where 0.05 ≤ X < 0.4.

[0025] The n-type waveguide layer 4 is _x Ga _x N, where 0≤X<1.

The multi-quantum well active layer 5 is composed of an InGaN quantum well 51 and a GaN quantum barrier 52, wherein the thickness of the InGaN quantum well 51 ranges from 5 to 30, and the In composition is 0.15 to 0.7, and the GaN quantum barrier 52 The thickness ranges from 50 to 200.

[0027] The material of the p-type waveguide layer 6 is I _ni _ _x Ga _x N, where 0≤X<1.

[0028] The material of the p-type confinement layer 7 is A — _x Ga _x N, where 0≤X<1.

[0029] The p-type layer 8 material is a Mg-doped gallium nitride having a thickness ranging from 100 to 4,000.

[0030] The p-type contact layer 9 is a Mg-doped gallium nitride having a thickness ranging from 5 to 100 people.

[0031] The foregoing method for fabricating a gallium nitride-based laser diode includes the steps of: 1) growing an n-type layer 2 on a substrate 1; 2) growing the first n-type confinement layer 31 on the n-type layer 2; 3) growing the second n-type confinement layer 32 on the first n-type confinement layer 31; 4) growing n on the second n-type confinement layer 32 The waveguide layer 4; 5) the active layer 5 is grown on the n-type waveguide layer 4; 6) the p-type waveguide layer 6 is grown on the active layer 5; 7) the p-type confinement layer 7 is grown on the p-type waveguide layer 6. 8) growing the p-type layer 8 on the p-type confinement layer 7; 9) growing the p-type contact layer 9 on the p-type layer 8.

[0032] Specifically, after the growth of the n-type layer is completed, the n-type confinement layer and the n-type waveguide layer are grown, firstly cooled to 900 to 1 000 ° C, and the cavity pressure is lowered to 50 to 100 torr for the first n-type confinement layer. Growth. During the growth of the AlN/AlGaN superlattice, the temperature and pressure are unchanged, and the growth of the superlattice structure is achieved by switching the gas composition. After the end, the A1 source gas flow rate is increased and the temperature is adjusted to the AlGaN growth temperature to grow a second n-type confinement layer. After the end, the temperature is lowered to 700~850 °C, and the cavity pressure is raised to 200~500torr to grow the n-type waveguide layer. After the growth is completed, the temperature is lowered and the pressure of the chamber is adjusted to an appropriate parameter for multi-quantum well structure epitaxy. After the growth is completed, the temperature is raised to perform p-type waveguide layer epitaxy. After completion, adjust the temperature, pressure and gas flow for p-type confinement layer extension. Further, p-type layer epitaxy is carried out, and the growth temperature is between 800 ° C and 1000 ° C, and then p - type contact layer epitaxy is carried out, and the growth temperature is between 800 ° C and 900 ° C. At this point, the epitaxial structure is over.

[0033] In the present invention, the AlN/AlGaN superlattice is used as the n-type confinement underlayer, which can effectively improve the A1 composition of the n-type confinement layer and reduce the laser lasing threshold; effectively prevent the epitaxial layer from cracking and improve Product yield.

[0034] It should be noted that although the n-type confinement layer shown in the above embodiment includes a stacked structure of a first n-type confinement layer (A1N/A1 GaN superlattice) and a second n-type confinement layer (AlGaN), practical The stack structure may also be formed by alternately forming a superlattice structure between the first n-type confinement layer and the second n-type confinement layer of AlGaN. In addition, although the laser diode shown in the above embodiment has a blue light emission wavelength, the light emission wavelength may be green light or within the blue light to green light wavelength band.

[0035] It is to be understood that the above-described embodiments are a preferred embodiment of the present invention, and the scope of the present invention is not limited to the embodiments, and any modifications made in accordance with the present invention are within the scope of the present invention.

[0036]

Claims

Claim

[Claim 1] A gallium nitride-based laser diode comprising: a substrate, an n-type layer, an n-type confinement layer, and an n-type waveguide layer

The active layer, the p-type waveguide layer, the p-type confinement layer and the p-type layer are characterized in that: the n-type confinement layer comprises a stacked structure of a first n-type confinement layer and a second n-type confinement layer.

[Claim 2] The gallium nitride-based laser diode according to claim 1, wherein: the first n-type confinement layer is A1N, the second n-type confinement layer is AlGaN, and the stacked structure is super-crystal Grid structure.

[Claim 3] The gallium nitride-based laser diode according to claim 1, wherein: the first n-type confinement layer is an AlN/AlGaN superlattice structure, and the second n-type confinement layer is AlGaN .

[Claim 4] The gallium nitride-based laser diode according to claim 2 or 3, wherein the Al1 composition of the AlGaN in the superlattice structure is not more than 20%.

[Claim 5] The gallium nitride-based laser diode according to claim 2 or 3, wherein: the AlGaN has a thickness of 10 to 30 persons in the superlattice structure, and the A1N has a thickness of 2 to 10 persons.

[Claim 6] A method for preparing a gallium nitride-based laser diode, the process steps of which include:

Forming an n-type layer over a substrate;

Forming an n-type confinement layer on the n-type layer, the n-type confinement layer comprising a stacked structure of a first n-type confinement layer and a second n-type confinement layer;

Forming an n-type waveguide layer on the n-type confinement layer;

Forming a multiple quantum well active layer on the n-type waveguide layer;

Forming a p-type waveguide layer on the active layer;

Forming a p-type confinement layer on the p-type waveguide layer;

A p-type layer is formed on the p-type confinement layer.

[Claim 7] A method of fabricating a gallium nitride-based laser diode according to claim 1, wherein

The first n-type confinement layer is A1N, the second n-type confinement layer is AlGaN, and the stacked structure is a superlattice structure.

[Claim 8] The method for fabricating a gallium nitride-based laser diode according to claim 1, wherein: the first n-type confinement layer is an AlN/AlGaN superlattice structure, and the second n The type of limiting layer is AlGaN.

[Claim 9] The method for producing a gallium nitride-based laser diode according to claim 7 or 8, wherein the superlattice structure has a growth temperature of 900 ° C to 1000 ° C.

[Claim 10] The method for fabricating a gallium nitride-based laser diode according to claim 7 or 8, wherein the superlattice structure has a growth pressure of 50 torr to 200 torr.