CN211208457U

CN211208457U - Non-mismatch II-type superlattice structure based on antimony shutter switch

Info

Publication number: CN211208457U
Application number: CN202020223057.9U
Authority: CN
Inventors: 徐志成; 朱艺红; 梁钊铭; 陈凯豪; 陈建新
Original assignee: Shanghai Institute of Technical Physics of CAS
Current assignee: Zhongke aibisaisi (Changzhou) Photoelectric Technology Co.,Ltd.
Priority date: 2020-02-28
Filing date: 2020-02-28
Publication date: 2020-08-07
Anticipated expiration: 2030-02-28

Abstract

The patent discloses a mismatch-free class II superlattice structure based on an antimony shutter switch. The single-period structure comprises a three-layer structure of a GaSb layer, an InAs layer and an InAsSb interface layer. The preparation method comprises the steps of directly growing an InAs layer after GaSb grows in the growth process of the II-type superlattice periodic structure, and opening an Sb shutter after InAs grows so As to perform element replacement on Sb and As in the InAs layer, thereby forming an InAsSb interface layer. It is characterized in that: because the direct growth of the InSb interface layer is cancelled, the InAsSb interface layer is formed by introducing Sb infiltration only after the InAs grows, the requirement of stress compensation is met, the difficulty of the interface preparation process is simplified, in addition, the island-mounted structure defect introduced when the large mismatch InSb interface directly grows is avoided, and the material performance is improved.

Description

Non-mismatch II-type superlattice structure based on antimony shutter switch

Technical Field

The patent relates to a superlattice material, in particular to a mismatch-free II-type superlattice structure based on an antimony shutter switch, which is applied to an infrared focal plane detector.

Background

In the early 20 th century, scientists L in IBM laboratories, Esaki and Sakaki proposed the concept of InAs/GaSb class II superlattices, and then, at the end of the 80 th century, Smith and Maihiot proposed the idea that InAs/GaSb class II superlattices can be applied to infrared detection technology.

At present, high-quality InAs/GaSb II-type superlattice materials are generally grown on a GaSb substrate, because 0.6 percent of lattice mismatch exists between InAs and the GaSb of the substrate, in order to obtain superlattice materials with wavelength-level thickness, an InSb interface layer with a larger lattice constant than that of GaSb needs to be grown for strain compensation, and generally, an InAs/GaSb II-type superlattice structure mainly comprises a GaSb layer, an InAs-on-GaSb interface layer, an InAs layer and a GaSb-on-InAs interface layer, wherein the InAs-on-GaSb interface and the GaSb-on-InAs interface are formed by the grown InSb interface layer, the method solves the problem of lattice mismatch between the InAs/GaSb superlattice and the substrate, but the method for obtaining the mismatch-free materials brings some difficulties for the growth and preparation of the superlattice, for example, (1) because the lattice mismatch between the InSb and the GaSb is as high as 6.3 percent, when the InSb interface layer is directly epitaxial on GaSb or InAs, the InSb interface layer grows in an island-shaped structure, the surface roughness of the superlattice material is increased, the surface of the material becomes rough along with the increase of the thickness of the epitaxial material, the thickness of the epitaxial layer of the superlattice infrared detection material is seriously limited, and the improvement of the quantum efficiency of the infrared detector is limited. (2) In order to epitaxially grow the InSb interface layer, the shutter opening and closing time of four elements of In, As, Ga and Sb needs to be strictly controlled, and the shutter opening and closing sequence at the interface needs to be carefully designed, so that the complexity of the growth process of the superlattice material MBE is increased, and the probability of introducing surface point defects is increased due to the excessively frequent shutter opening and closing. (3) Because lattice mismatch between InSb and GaSb is large, defects and dislocation are easily introduced when an InSb interface layer is epitaxially grown, and the crystal quality of the material is reduced. (4) After InAs growth is finished, residual As in the MBE cavity can enter the GaSb layer to form GaAsSb due to the higher saturated vapor pressure of As, and the mismatch degree of the superlattice material and the substrate is increased.

Disclosure of Invention

The patent aims to provide a mismatch-free II-type superlattice structure based on an antimony shutter switch and a preparation method thereof, and the technical problems that the mismatch-free II-type superlattice structure is formed by the following steps:

1. the island-shaped structure causes the problem of rough surface when the large mismatch InSb interface layer grows epitaxially;

2, the problem of complex process when the InSb interface layer is directly epitaxially grown;

3, defects and dislocation are easily introduced when the InSb interface layer is directly epitaxially grown;

4, the As background pressure is high after InAs growth is finished;

as shown in fig. 1, the class II superlattice structure of this patent is: from bottom to top, the substrate is sequentially provided with a GaSb layer 1, an InAs layer 2 and InAs_xSb_1-xLayer 3. Wherein:

the thickness of the GaSb layer 1 is 1.05nm-2.4 nm;

the thickness of the InAs layer 2 is 1.2nm-3.0 nm;

said InAs_xSb_1-xThe thickness of layer 3 is 0.3nm, the composition x is 0.01-0.5;

the preparation method comprises the following steps:

1) heating the GaSb substrate to a deoxidation temperature, and removing an oxide layer on the surface of the GaSb substrate under the protection of Sb beam, wherein the deoxidation temperature is between 560 and 580 ℃, and the Sb beam is not less than 1 × 10^-6Torr；

2) Cooling the GaSb substrate to the growth temperature of the II-type superlattice, wherein the growth temperature range is 395-405 ℃;

3) setting the As/In and Sb/Ga growth beam current ratio to a range for II type superlattice growth;

4) growing InAs/GaSb II type superlattice on a GaSb substrate by adopting a molecular beam epitaxy method, opening an epitaxial GaSb layer 1 by a shutter of Ga and Sb, opening an epitaxial InAs layer 2 by an In shutter and an As shutter, opening an Sb shutter only, introducing Sb beam to soak for 1-6s, and performing element replacement with As In the InAs layer to form InAs_xSb_1-xLayer 3. And then circulating back and forth until the growth of the material is finished.

The advantage of this patent lies in: (1) an InSb interface layer behind GaSb is eliminated, and the InAsSb interface layer is formed only by opening a Sb shutter beam for infiltration after the growth of InAs is finished, so that the process steps for preparing the II-type superlattice material interface are greatly simplified, the complexity of controlling a shutter switch of a mismatch-free superlattice material is reduced, and the problem of increase of surface point defects caused by frequent opening and closing of the shutter is solved; (2) the InAsSb interface layer is formed in an element replacement mode through Sb beam infiltration, the island-shaped structure growth problem caused by direct epitaxial growth of the InSb interface layer is avoided, and the surface roughness of the superlattice material is reduced; (3) interface defects and dislocation caused by direct epitaxial growth of an InSb interface are avoided; (4) the Sb beam infiltration behind the InAs layer reduces the probability of As entering the GaSb layer and improves the purity of the material.

Description of the drawings:

FIG. 1 is a model of a three-layer structure of an InAs/GaSb class II superlattice; 1 is GaSb layer, 2 is InAs layer, 3 is InAs layer_xSb_1-xAnd (3) a layer.

FIG. 2 is a schematic view of the next sequential order of shutter opening and closing in one growth cycle of InAs/GaSb class II superlattice materials.

Detailed Description

Example 1

According to the invention, a class II superlattice material is prepared, and the specific structure is as follows:

the thickness of the GaSb layer 1 is 1.05 nm;

the thickness of the InAs layer 2 is 2.45 nm;

InAs_xSb_1-xthe thickness of layer 3 is 0.3nm, the composition x is 0.20;

the specific preparation method comprises the following steps:

1) heating the GaSb substrate to a deoxidation temperature, and removing an oxide layer on the surface of the GaSb substrate under the protection of an Sb beam, wherein the deoxidation temperature is 560 ℃, and the Sb beam is 2 × 10^-6Torr；

2) Cooling the GaSb substrate to the growth temperature of II-type superlattice 395 ℃;

3) setting the As/In and Sb/Ga growth beam current ratios to be 4 and 5 respectively;

4) growing InAs/GaSb II type superlattice on a GaSb substrate by adopting a molecular beam epitaxy method, opening an epitaxial GaSb layer 1 of a shutter of Ga and Sb In the first step, opening an epitaxial InAs layer 2 of an In shutter and an As shutter In the second step, opening only the Sb shutter In the third step, introducing Sb beam to soak for 3s, and performing element replacement with As In the InAs layer to form InAs_xSb_1-xLayer 3. And then circulating back and forth until the growth of the material is finished.

Example 2

the thickness of the GaSb layer 1 is 2.1 nm;

the thickness of the InAs layer 2 is 1.2 nm;

InAs_xSb_1-xthe thickness of the layer 3 was 0.3nm, the composition x was 0.39, and the Sb wetting time was 1 s;

the specific preparation method comprises the following steps:

1) heating the GaSb substrate to a deoxidation temperature, and removing an oxide layer on the surface of the GaSb substrate under the protection of Sb beam, wherein the deoxidation temperature is 570 ℃, and the Sb beam is2×10^-6Torr；

2) Cooling the GaSb substrate to the II-type superlattice growth temperature of 400 ℃;

4) growing InAs/GaSb II type superlattice on a GaSb substrate by adopting a molecular beam epitaxy method, opening an epitaxial GaSb layer 1 by a shutter of Ga and Sb, opening an epitaxial InAs layer 2 by an In shutter and an As shutter, opening an Sb shutter only, introducing Sb beam to soak for 1s, and performing element replacement with As In the InAs layer to form InAs_xSb_1-xLayer 3. And then circulating back and forth until the growth of the material is finished.

Example 3

According to the invention, we have prepared a third class II superlattice material, which has the specific structure:

the thickness of the GaSb layer 1 is 2.4 nm;

the thickness of the InAs layer 2 is 3.0 nm;

InAs_xSb_1-xthe thickness of layer 3 is 0.3nm, the composition x is 0.02;

the specific preparation method comprises the following steps:

1) heating the GaSb substrate to a deoxidation temperature, and removing an oxide layer on the surface of the GaSb substrate under the protection of Sb beam, wherein the deoxidation temperature is 580 ℃, and the Sb beam is 2 × 10^-6Torr；

2) Cooling the GaSb substrate to the growth temperature of the II-type superlattice of 405 ℃;

4) growing InAs/GaSb II type superlattice on a GaSb substrate by adopting a molecular beam epitaxy method, opening an epitaxial GaSb layer 1 of a shutter of Ga and Sb In the first step, opening an epitaxial InAs layer 2 of an In shutter and an As shutter In the second step, opening only the Sb shutter In the third step, introducing Sb beam to soak for 6s, and forming InAs by carrying out element replacement with As In the InAs layer_xSb_1-xLayer 3. And then circulating back and forth until the growth of the material is finished.

Claims

1. A mismatch-free class II superlattice structure based on an antimony shutter switch is characterized in that:

the superlattice structure is as follows: the substrate comprises a GaSb layer (1), an InAs layer (2) and InAs from bottom to top in sequence_xSb_1-xA layer (3);

the thickness of the GaSb layer (1) is 1.05nm-2.4 nm;

the thickness of the InAs layer (2) is 1.2nm-3.0 nm;

said InAs_xSb_1-xThe thickness of the layer (3) was 0.3 nm.