阅读说明：本技术 一种具有低n面串联接触电阻的半导体激光器 (Semiconductor laser with low N-surface series contact resistance ) 是由 林涛 解佳男 穆妍 孙婉君 李亚宁 于 2021-07-30 设计创作，主要内容包括：一种具有低N面串联接触电阻的半导体激光器,包括从上至下依次设置的：P面电极,P型欧姆接触层,P型限制层,上波导层,量子阱,下波导层,N型限制层,N型缓冲层,N型衬底,N型重掺杂层,N面电极。本发明具有低N面串联接触电阻的半导体激光器,采用在N型衬底上制备一层N型重掺杂层,该重掺杂层与N面复合金属电极形成良好欧姆接触使其具有低N面串联接触电阻,可解决长期以来N型衬底无法同时保证重掺杂和低缺陷、低杂质光吸收的问题,可以有效解决N面电极接触电阻大的问题。(A semiconductor laser with low N-plane series contact resistance, comprising, in order from top to bottom: the semiconductor device comprises a P-surface electrode, a P-type ohmic contact layer, a P-type limiting layer, an upper waveguide layer, a quantum well, a lower waveguide layer, an N-type limiting layer, an N-type buffer layer, an N-type substrate, an N-type heavily doped layer and an N-surface electrode. The semiconductor laser with the low N-surface series contact resistance is characterized in that an N-type heavily doped layer is prepared on an N-type substrate, and the heavily doped layer and an N-surface composite metal electrode form good ohmic contact to enable the heavily doped layer to have the low N-surface series contact resistance, so that the problem that the N-type substrate cannot simultaneously guarantee heavy doping, low defect and low impurity light absorption for a long time can be solved, and the problem that the N-surface electrode has large contact resistance can be effectively solved.)

1. The utility model provides a semiconductor laser with low N face series connection contact resistance which characterized in that, including from last to setting gradually down: the semiconductor device comprises a P-surface electrode (1), a P-type ohmic contact layer (2), a P-type limiting layer (3), an upper waveguide layer (4), a quantum well (5), a lower waveguide layer (6), an N-type limiting layer (7), an N-type buffer layer (8), an N-type substrate (9), an N-type heavily doped layer (10) and an N-surface electrode (11).

2. A semiconductor laser with low N-plane series contact resistance according to claim 1, characterized in that the N-type substrate (9) has a thickness of 90-180 μm.

3. The semiconductor laser with low N-plane series contact resistance as claimed in claim 1, wherein the N-type heavily doped layer (10) is formed on the contact surface of the N-type substrate (9) and the N-plane electrode (11) and has a thickness in the range of 0.02 to 5 μm and a doping concentration in the range of 10¹⁸～10²⁰cm^-3The doping concentration of the N-type heavily doped layer (10) is reduced along with the distance from the contact surface, and the N-type heavily doped layer (10) is higher than the N-type substrate (9).

Technical Field

The invention belongs to the technical field of semiconductor lasers, and particularly relates to a semiconductor laser with low N-surface series contact resistance.

Background

The preparation of metal-semiconductor ohmic contact is an important process step in the preparation process of semiconductor laser. The series resistance introduced by the ohmic contact affects not only the operating voltage, output power and conversion efficiency of the device, but also the thermal stability of the device, thereby affecting the reliability and lifetime of the device. The optimized ohmic contact can not only reduce the series resistance of the device, improve the output power and the photoelectric conversion efficiency of the laser, but also improve the stability and the reliability of the chip during working. Therefore, the requirements for ohmic contact are linear volt-ampere characteristics, low contact resistance, low minority carrier injection, stability and reliability. This is crucial for high power semiconductor lasers.

There are four common types of ohmic contacts: surface high doping type (tunnel penetration type), low potential barrier type, high recombination rate type, and barrier-free type. Semiconductor lasers are mostly manufactured on N-type III-V compound substrates, and most of the semiconductor lasers are in ohmic contact in a surface highly-doped mode no matter in laboratories or factories. That is, in the case of forming an ohmic contact on the N-plane of the semiconductor laser, a tunnel penetration type ohmic contact is often formed. When metal is contacted with semiconductor, the doping concentration of the semiconductor is high, the width of the potential barrier is very thin, electrons can penetrate through the potential barrier through the tunneling effect to generate considerable tunnel current, and the contact resistance is very low, so that the metal-semiconductor contact can be used as ohmic contact. When the semiconductor material is heavily doped, the contact between the semiconductor material and the metal can form good ohmic contact.

The semiconductor laser is usually prepared on an N-type substrate, and two problems exist in the process of improving the doping concentration of the N-type substrate, namely the difficulty in realizing the process, and the crystal quality is influenced by the increase of crystal defects due to the excessively high doping concentration. The doping concentration of the N-type substrate is usually 10¹⁸On the order of magnitude, the specific ohmic contact resistivity of the metal electrode is mostly 10^-5On the order of magnitude, the specific ohmic contact resistivity of the P surface of the semiconductor laser due to the existence of the heavily doped layer is mostly 10^-6And the two are different by one order of magnitude.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a semiconductor laser with low N-surface series contact resistance, wherein an N-surface electrode adopts a composite metal structure, a heavily doped layer is prepared between an N-type substrate and the N-surface electrode, the doping concentration of the heavily doped layer is greater than that of the N-type substrate, and the doping concentration of the heavily doped layer can be adjusted according to the specific design requirements of the semiconductor laser, so that the heavily doped layer can form ohmic contact with the composite metal electrode with low series resistance, and the specific contact resistivity of the N-surface ohmic contact of the semiconductor laser is reduced.

In order to achieve the purpose, the invention adopts the technical scheme that: a semiconductor laser with low N-face series contact resistance comprises a plurality of semiconductor laser units which are sequentially arranged from top to bottom: the semiconductor device comprises a P-surface electrode, a P-type ohmic contact layer, a P-type limiting layer, an upper waveguide layer, a quantum well, a lower waveguide layer, an N-type limiting layer, an N-type buffer layer, an N-type substrate, an N-type heavily doped layer and an N-surface electrode.

The thickness of the N-type substrate is 90-180 mu m.

The N-type heavily doped layer is arranged on the contact surface of the N-type substrate and the N-surface electrode, the thickness range of the N-type heavily doped layer is 0.02-5 mu m, and the doping concentration range is 10¹⁸～10²⁰cm^-3The doping concentration of the N-type heavily doped layer is reduced along with the distance from the contact surface, and the N-type heavily doped layer is higher than the N-type substrate.

The N-type heavily doped layer is located between the N-type substrate and the N-side electrode, and the thickness range of the N-type heavily doped layer is 1-5 mu m.

The invention has the beneficial effects that:

the N-type heavily doped layer and the composite metal electrode form ohmic contact with low series resistance, a proper region can be selected in the heavily doped layer to carry out heavily doping according to the structure of the semiconductor laser, and the doping concentration of the heavily doped layer can be changed according to the requirement of the designed laser on the series resistance of the N-surface electrode. The structure can solve the problem that the N-type substrate can not ensure heavy doping, low defect and impurity absorption at the same time for a long time, and can effectively solve the problem of large contact resistance of the N-surface electrode.

Drawings

Fig. 1 is a schematic view of a semiconductor laser with low N-plane series contact resistance according to the present invention.

Fig. 2 is a schematic structural view of a semiconductor laser having a low N-plane series contact resistance according to embodiment 1.

FIG. 3 shows the relation between the specific contact resistivity and the doping concentration of N-GaAs.

In the figure, a 1-P surface electrode, a 2-P type ohmic contact layer, a 3-P type limiting layer, a 4-upper waveguide layer, a 5-quantum well, a 6-lower waveguide layer, a 7-N type limiting layer, an 8-N type buffer layer, a 9-N type substrate, a 10-N type heavily doped layer and an 11-N surface electrode are arranged.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Referring to fig. 1, a semiconductor laser with low N-plane series contact resistance includes, from top to bottom: the light-emitting diode comprises a P-surface electrode 1, a P-type ohmic contact layer 2, a P-type limiting layer 3, an upper waveguide layer 4, a quantum well 5, a lower waveguide layer 6, an N-type limiting layer 7, an N-type buffer layer 8, an N-type substrate 9, an N-type heavily doped layer 10 and an N-surface electrode 11.

The thickness of the N-type substrate 9 is 90-180 μm.

The N-type heavily doped layer 10 is formed on the contact surface of the N-type substrate 9 and the N-surface electrode 11 by ion implantation, diffusion or epitaxy, the thickness range is 0.02-5 μm, and the doping concentration range is 10¹⁸～10²⁰cm^-3The doping concentration of the N-type heavily doped layer 10 is highest at the interface with the N-side electrode 11, and decreases with distance from the interface, but is still higher than the N-type substrate 9.

The N-type heavily doped layer 10 is located between the N-type substrate and the N-side electrode, and the thickness range of the N-type heavily doped layer is 0.02-5 mu m.

The working principle of the invention is as follows:

according to the invention, the N-type heavily-doped layer 10 is added between the N-type substrate 9 and the N-surface electrode 11 in the semiconductor laser structure, and as the doping concentration of the N-type heavily-doped layer 10 is higher than that of the N-type substrate 9, the N-type heavily-doped layer 10 can form good ohmic contact with the N-surface electrode 11 due to the higher doping concentration, and has low series resistance.

Example 1

Refer to FIG. 2, asThe laser with low N-plane series contact resistance of embodiment 1 of the present invention is schematically illustrated. In example 1, a 808nm semiconductor laser was used as an example, and the cavity length was 2000 μm and the stripe width was 200 μm. The N-face electrode adopts a composite metal electrode structure, and the N-type heavily doped layer is prepared on the N-type GaAs substrate by ion implantation, diffusion or epitaxy. The device structure comprises an N-surface electrode, an N-type heavily doped layer, an N-type GaAs substrate and N-type Al_0.12GaAs buffer layer, N-type Al_0.5GaAs confining layer, Al_0.33GaAs lower waveguide layer, Al_0.12Ga_0.795In_0.085As quantum well, Al_0.33GaAs upper waveguide layer, P-type Al_0.5GaAs limiting layer, P-type GaAs ohmic contact layer and P-face electrode.

The thickness of the N-face electrode is 0.41 mu m, the thickness of the N-type heavily doped layer is 0.02 mu m, the thickness of the N-type substrate is 100 mu m, the thickness of the N-type buffer layer is 0.15 mu m, the thickness of the N-type limiting layer is 1.2 mu m, the thickness of the lower waveguide layer is 0.45 mu m, the thickness of the quantum well is 7nm, the thickness of the upper waveguide layer is 0.45 mu m, the thickness of the P-type limiting layer is 1.2 mu m, the thickness of the P-type ohmic contact layer is 0.15 mu m, and the thickness of the P-face electrode is 0.2 mu m.

FIG. 3 is a relation between the N-GaAs specific contact resistivity and the doping concentration obtained by fitting, and the specific contact resistivity of the N-GaAs is reduced along with the increase of the doping concentration. It can be seen that when the doping concentration reaches 10¹⁹In order of magnitude, the specific contact resistivity can be reduced to 10^-6An order of magnitude.