阅读说明：本技术 一种限制增强型GaN基深紫外激光器 (Limit enhancement mode gaN base deep ultraviolet laser ) 是由 赵德刚 梁锋 王泓江 于 2020-08-31 设计创作，主要内容包括：本发明提供了一种限制增强型GaN基深紫外激光器,自下往上依次是N型电极、衬底、N型下限制层、N型Al<Sub>x</Sub>Ga<Sub>1-x</Sub>N下波导层、有源区、P型Al<Sub>x</Sub>Ga<Sub>1-x</Sub>N上波导层、P型电子阻挡层、P型上限制层、P型GaN欧姆接触层和P型电极；所述N型Al<Sub>x</Sub>Ga<Sub>1-x</Sub>N下波导层和P型Al<Sub>x</Sub>Ga<Sub>1-x</Sub>N上波导层均为Al组分渐变型,利用N型Al<Sub>x</Sub>Ga<Sub>1-x</Sub>N下波导层和P型Al<Sub>x</Sub>Ga<Sub>1-x</Sub>N上波导层中的Al组分渐变设计引导光场靠近有源区,降低光学损耗,增强量子阱对载流子的限制,抑制电子泄露,改善阈值和输出功率。(The invention provides a limited enhanced GaN-based deep ultraviolet laser which comprises an N-type electrode, a substrate, an N-type lower limiting layer and N-type Al from bottom to top in sequence x Ga 1‑x N lower waveguide layer, active region, P-type Al x Ga 1‑x The N-type upper waveguide layer, the P-type electron blocking layer, the P-type upper limiting layer, the P-type GaN ohmic contact layer and the P-type electrode are arranged on the N-type upper waveguide layer; the N type Al x Ga 1‑x N lower waveguide layer and P-type Al x Ga 1‑x The N upper waveguide layers are all of Al component graded type, and N type Al is utilized x Ga 1‑x N lower waveguide layer and P-type Al x Ga 1‑x The Al component in the N upper waveguide layer is designed to guide the optical field to be close to the active region in a gradual change mode, so that the optical loss is reduced, the limit of a quantum well on a current carrier is enhanced, the electronic leakage is inhibited, and the threshold value and the output power are improved.)

1. A limited enhancement type GaN-based deep ultraviolet laser is characterized in that the limited enhancement type GaN-based deep ultraviolet laser is arranged from bottom to topAn N-type electrode (1), a substrate (2), an N-type lower limiting layer (3) and N-type Al are arranged in sequence_xGa_1-xN lower waveguide layer (4), active region (5), P type Al_xGa_1-xAn N upper waveguide layer (6), a P type electron blocking layer (7), a P type upper limiting layer (8), a P type ohmic contact layer (9) and a P type electrode (10); wherein the N-type Al_xGa_1-xN lower waveguide layer (4) and P type Al_xGa_1-xThe N upper waveguide layer (6) is made of Al_xGa_1-xN; in the N-type Al_xGa_1-xIn the N lower waveguide layer (4), Al is from bottom to top_xGa_1-xThe x of the N material is gradually reduced from 0.6 to 0.5; in P type Al_xGa_1-xIn the N upper waveguide layer (6), Al is from bottom to top_xGa_1-xThe x of the N material is gradually increased from 0.5 to 0.6, and N type Al is utilized_xGa_1-xN lower waveguide layer (4) and P type Al_xGa_1-xThe molar component gradual change design of Al in the N upper waveguide layer (6) guides an optical field to be close to an active region, so that the optical loss is reduced, the limit of a quantum well to a current carrier is enhanced, the electronic leakage is inhibited, and the threshold value and the output power are improved.

2. The confined enhanced GaN-based DUV laser as claimed in claim 1, wherein the N-type Al is_xGa_1-xThe thickness of the N lower waveguide layer (4) is 120 nm; p type Al_xGa_1-xThe thickness of the N upper waveguide layer (6) is 120 nm.

3. The confined enhanced GaN-based deep ultraviolet laser as claimed in claim 1, wherein the active region (5) is composed of 3 AlGaN quantum barrier layers and 2 AlGaN quantum well layers alternately; the 3 AlGaN quantum barrier layers are all Al_0.5Ga_0.5N, the thickness of the single-layer quantum barrier is 11 nm; the 2 AlGaN quantum well layers are all Al_0.4Ga_0.6And N, the thickness of the single-layer quantum well is 2.5 nm.

4. The confined enhanced GaN-based deep ultraviolet laser according to claim 1, 2 or 3,the P-type electron blocking layer (7) is made of Al_0.7Ga_0.3N, thickness 20 nm.

5. The confined enhanced GaN-based deep ultraviolet laser as claimed in claim 4, wherein the material of the P-type upper confinement layer (8) is Al_0.55Ga_0.45N, thickness 2.3 μm.

6. A confined enhancement GaN-based deep ultraviolet laser according to claim 5, characterized in that the thickness of the P-type ohmic contact layer (9) is 60 nm.

7. The confined enhanced GaN-based deep ultraviolet laser as claimed in claim 6, wherein the P-type electrode (10) is composed of Pd/Pt/Au and has a thickness of 80nm/80nm/560 nm.

8. The confined enhanced GaN-based deep ultraviolet laser as claimed in claim 7, wherein the material of the N-type lower confinement layer (3) is Al_0.55Ga_0.45N, thickness 2 μm.

9. A confined enhanced GaN-based deep ultraviolet laser according to claim 8, characterized in that the substrate (2) is an AlN substrate with a thickness of 100 μm.

Technical Field

The invention relates to the technical field of semiconductor laser devices, in particular to a limited enhanced GaN-based deep ultraviolet laser.

Background

The GaN-based semiconductor material comprises GaN, InN, AlN and ternary and quaternary alloy compounds thereof, the forbidden bandwidth is continuously adjustable from 0.7eV to 6.2eV, the luminescence spectrum covers the band from infrared to deep ultraviolet, and the GaN-based semiconductor material is a preferred material for preparing GaN-based ultraviolet lasers. Compared with the traditional solid and gas ultraviolet laser, the GaN-based ultraviolet laser has the excellent characteristics of high response rate, long service life, high efficiency, small volume, low power consumption, energy conservation, environmental protection, good stability and the like, is widely applied to the fields of ultraviolet curing, data storage, material processing, disinfection and sterilization, ultraviolet lithography, biological detection and the like, and is a new hot spot of current domestic and foreign research.

However, there are certain difficulties in fabricating high performance GaN-based deep ultraviolet lasers. In order to obtain a uv laser with a shorter wavelength and higher energy, the Al content in the AlGaN layer needs to be increased. However, the AlGaN material with high Al composition generates strong spontaneous polarization in the crystal due to non-centrosymmetry of the unit cell, and the strong polarization field causes spatial separation of the wave functions of electrons and holes, thereby reducing the radiative recombination rate of carriers. Meanwhile, the AlGaN material generates a large amount of dislocation and residual strain due to the lack of a substrate with lattice matching in the epitaxial growth process, so that the wafer is bent and cracked, the optical loss is greatly increased, and the quality of crystals is seriously reduced. In addition, for GaN-based ultraviolet lasers, Mg is generally used as a P-type dopant. However, the activation energy of the Mg acceptor is high, and the activation energy is correspondingly increased with the increase of the Al component in the AlGaN material, which may cause the difficulty of P-type doping to increase, and the conductivity of the hole to decrease, thereby affecting the transmission of the hole to the active region, and increasing the absorption loss and the threshold current of the GaN-based deep ultraviolet laser.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a limited enhancement type GaN-based deep ultraviolet laser, and an AlGaN layer with gradually changed Al components is adopted in a waveguide layer near a quantum well, so that the optical field can be effectively limited, the limitation of carriers in the quantum well can be enhanced, the electronic leakage is reduced, the threshold value of the laser is expected to be reduced, and the output power is improved.

The present invention achieves the above-described object by the following technical means.

A limit-enhanced GaN-based deep ultraviolet laser comprises an N-type electrode, a substrate, an N-type lower limit layer, and an N-type Al layer from bottom to top_xGa_1-xN lower waveguide layer, active region, P-type Al_xGa_1-xThe N-type upper waveguide layer, the P-type electron blocking layer, the P-type upper limiting layer, the P-type ohmic contact layer and the P-type electrode are arranged on the N-type upper waveguide layer; wherein the N-type Al_xGa_1-xN lower waveguide layer (4) and P type Al_xGa_1-xThe N upper waveguide layer (6) is made of Al_xGa_1-xN; in the N-type Al_xGa_1-xIn the N lower waveguide layer (4), Al is from bottom to top_xGa_1-xThe x of the N material is gradually reduced from 0.6 to 0.5; in P type Al_xGa_1-xIn the N upper waveguide layer (6), Al is from bottom to top_xGa_1-xThe x of the N material is gradually increased from 0.5 to 0.6; using N-type Al_xGa_1-xN lower waveguide layer and P-type Al_xGa_1-xThe molar component gradual change design of Al in the N upper waveguide layer guides an optical field to be close to an active region, so that the optical loss is reduced, the limit of a quantum well on a current carrier is enhanced, the electronic leakage is inhibited, and the threshold value and the output power are improved.

Further, N type Al_xGa_1-xThe thickness of the N lower waveguide layer is 120 nm. P type Al_xGa_1-xThe thickness of the N upper waveguide layer is 120 nm.

Further, the active region is composed of 3 AlGaN quantum barrier layers and 2 AlGaN quantum well layers in an alternating mode.

Further, all the 3 AlGaN quantum barrier layers are Al_0.5Ga_0.5And N, the thickness of the single-layer quantum barrier is 11 nm.

Further, the 2 AlGaN quantum well layers are all Al_0.4Ga_0.6And N, the thickness of the single-layer quantum well is 2.5 nm.

Further, the P-type electron blocking layer is made of Al_0.7Ga_0.3N, thickness 20 nm.

Further, the material of the P-type upper limiting layer is Al_0.55Ga_0.45N, wherein the Al component content is 0.55, and the thickness is 2.3 μm.

Further, the thickness of the P-type ohmic contact layer is 60 nm.

Furthermore, the P-type electrode is made of Pd/Pt/Au, and the thickness of the P-type electrode is 80nm/80nm/560 nm.

Further, the material of the N-type lower limiting layer is Al_0.55Ga_0.45N, thickness 2 μm.

Further, the substrate is an AlN substrate and has a thickness of 100 μm.

Advantageous effects

The lower waveguide layer and the upper waveguide layer are designed by adopting an aluminum gallium nitride structure with gradually changed Al components, and the refractive index of the waveguide layers is changed by adjusting the Al component content in the lower waveguide layer and the upper waveguide layer, so that the difference between the refractive index of the waveguide layers and the refractive index of an active region is gradually increased, the limiting effect on an optical field is enhanced, the distribution of the optical field in a P-type layer is reduced, and the optical loss is reduced.

In addition, by adjusting the Al component of the waveguide layer, the waveguide layer is matched with lattices between the limiting layer and the electron blocking layer, so that the polarization effect in the device is weakened, the energy band bending is relieved, the electron barrier height near the active region is increased, more electrons are limited in the quantum well, the leakage of the electrons is inhibited, and the threshold value and the output power are improved; due to lattice matching, dislocation and cracks inside the device are greatly reduced, non-radiative recombination centers are obviously reduced, and the quality of the GaN-based deep ultraviolet laser is improved, so that the high-performance GaN-based deep ultraviolet laser is realized.

Drawings

FIG. 1 is a schematic diagram of a confinement-enhanced GaN-based deep ultraviolet laser according to the present invention.

Fig. 2 is a schematic diagram of the energy bands (conduction bands) of the lower waveguide layer, the active region and the upper waveguide layer according to the present invention.

In the figure, 1, N-type electrode, 2, substrate, 3, N-type lower limiting layer, 4, N-type Al_xGa_1-xThe multilayer waveguide structure comprises a N lower waveguide layer, 5, an active region, 5a, a first AlGaN quantum barrier layer, 5b, a first AlGaN quantum well layer, 5c, a second AlGaN quantum barrier layer, 5d, a second AlGaN quantum well layer, 5e, a third AlGaN quantum barrier layer and 6, wherein the first AlGaN quantum barrier layer is arranged between the first AlGaN quantum well layer and the second AlGaN quantum well layer, and the third AlGaN quantum barrier layer is arranged between the first_xGa_1-xAn N upper waveguide layer, 7, a P type electron blocking layer, 8, a P type upper limiting layer, 9, a P type ohmic contact layer, 10 and a P type electrode.

Detailed Description

The invention will be further described with reference to the following figures and specific examples, but the scope of the invention is not limited thereto.

A confinement enhanced GaN-based deep violet as shown in fig. 1The external laser comprises an N-type electrode 1, a substrate 2, an N-type lower limiting layer 3 and N-type Al from bottom to top in sequence_xGa_1-xN lower waveguide layer 4, active region 5, P type Al_xGa_1-xAn N upper waveguide layer 6, a P type electron blocking layer 7, a P type upper limiting layer 8, a P type ohmic contact layer 9 and a P type electrode 10. More specifically:

the N-type electrode 1 is made of Ti/Al/Ti/Au material and has the thickness of 70/150/70/200 nm.

The substrate 2 was an AlN substrate and had a thickness of 100 μm.

An N-type lower limiting layer 3 is grown on the AlN substrate 2, and the material is Al_0.55Ga_0.45N, thickness 2 μm.

Growing N-type Al on the N-type lower limiting layer 3_xGa_1-xN lower waveguide layer 4, said N-type Al_xGa_1-xThe N lower waveguide layer 4 is made of Al_xGa_1-xN; and N type Al_xGa_1-xThe N lower waveguide layer 4 is Al component gradual change type, in particular to Al from bottom to top_xGa_1-xThe x of the N material gradually decreases from 0.6 to 0.5 (i.e., closer to the active region, the lower the Al composition), with a thickness of 120 nm.

N type Al as shown in FIG. 2_xGa_1-xAn active region 5 grows on the N lower waveguide layer 4, the active region 5 is sequentially formed by a first AlGaN quantum barrier layer 5a, a first AlGaN quantum well layer 5b, a second AlGaN quantum barrier layer 5c, a second AlGaN quantum well layer 5d and a third AlGaN quantum barrier layer 5e, wherein the first AlGaN quantum well layer 5b and the second AlGaN quantum well layer 5d are both Al_0.4Ga_0.6And N, the thickness of the single-layer quantum well is 2.5 nm. The first AlGaN quantum barrier layer 5a, the second AlGaN quantum barrier layer 5c and the third AlGaN quantum barrier layer 5e are all Al_0.5Ga_0.5And N, the thickness of the single-layer quantum barrier is 11 nm.

P-type Al is grown on the active region 5_xGa_1-xN upper waveguide layer 6, P type Al_xGa_1-xThe N upper waveguide layer 6 is made of Al_xGa_{1- x}N, and P type Al_xGa_1-xThe N upper waveguide layer 6 is Al component gradual change type, in particular to Al from bottom to top_xGa_1-xThe x of the N material gradually increases from 0.5 to 0.6 (i.e., further away from the active layer)Zone, higher Al composition), the thickness was 120 nm.

P type Al_xGa_1-xA P-type electron blocking layer 7 is grown on the N upper waveguide layer 6, and the material of the P-type electron blocking layer 7 is Al_0.7Ga_0.3N, thickness 20 nm.

A P-type upper limiting layer 8 is grown on the P-type electron barrier layer 7, and the material of the P-type upper limiting layer 8 is Al_0.55Ga_0.45N, thickness 2.3 μm.

And a P-type ohmic contact layer 9 is grown on the P-type upper limiting layer 8, the thickness of the P-type ohmic contact layer is 60nm, and the P-type ohmic contact layer 9 is made of GaN. The P-type electrode 10 is arranged on the P-type ohmic contact layer 9, the composition material is Pd/Pt/Au, and the thickness is 80nm/80nm/560 nm.

With reference to N-type Al as shown in FIG. 2_xGa_1-xN lower waveguide layer 4, active region 5 and P type Al_xGa_1-xThe band (conduction) diagram of the N upper waveguide layer 6. Due to N type Al_xGa_1-xThe Al composition of the N lower waveguide layer 4 gradually decreases and accordingly the effective barrier height of electrons also increases. Due to P type Al_xGa_1-xThe Al composition of the N upper waveguide layer 6 gradually increases and the effective barrier height of electrons also decreases. The quantum barrier layers 5a, 5c and 5e in the active region 5 have lower Al components than the N-type Al close to the active region_xGa_1-xN lower waveguide layer 4 and P type Al_xGa_1-xThe Al components in the N upper waveguide layer 6 and the Al components in the quantum barrier layers 5a, 5c, and 5e are all higher than the Al components in the quantum well layers 5b and 5d, and accordingly, the effective barrier height of electrons in the quantum well is the lowest. The quantum well can not only enhance the limit of the quantum well to the carrier and reduce the electronic leakage, but also limit the light to the active region and reduce the optical loss.

The present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.