CN216980589U

CN216980589U - Inverted 3-5-mu-m nBn type InAsSb infrared detector material structure

Info

Publication number: CN216980589U
Application number: CN202122792477.6U
Authority: CN
Inventors: 陈冬琼; 邓功荣; 杨文运; 宋欣波; 何燕; 赵宇鹏; 尚发兰; 戴欣冉; 黎秉哲; 范明国; 龚晓霞; 太云见; 黄晖
Original assignee: Kunming Institute of Physics
Current assignee: Kunming Institute of Physics
Priority date: 2021-11-15
Filing date: 2021-11-15
Publication date: 2022-07-15
Anticipated expiration: 2031-11-15

Abstract

The utility model relates to an inverted 3-5 mu m nBn type InAsSb infrared detector material structure, belonging to the technical field of photoelectron materials and devices. The infrared detector material structure comprises a top electrode contact layer, an absorption layer, a barrier layer, a bottom electrode contact layer, a buffer layer and a substrate which are sequentially arranged from top to bottom. By improving the structure and adopting an inverted extended wavelength nBn structure, the response wavelength of the infrared detector prepared by the material is extended to 5 mu m, and meanwhile, the transverse diffusion current can be reduced under the condition of not increasing the dark current of the infrared detector, so that the performance of the infrared detector is further improved.

Description

Inverted 3-5-mu-m nBn type InAsSb infrared detector material structure

Technical Field

The utility model relates to an inverted 3-5 mu m nBn type InAsSb infrared detector material structure, belonging to the technical field of photoelectron materials and devices.

Background

In the prior art, the InAsSb material has the advantages of long service life of a current carrier, large absorption coefficient, high mobility of the current carrier and the like, and is an infrared photoelectric material with wide application prospect. The InAsSb material with the Sb component of 0.09 is in lattice matching with the GaSb substrate, the prepared detector can work at 150K or even at the room temperature, has higher sensitivity and detection rate, is a good choice for a medium-long wave infrared detection system with low power consumption, miniaturization, high sensitivity and quick response, but has the cut-off wavelength of only 4.2 mu m when the detector works at 150K, and limits the application range. How to improve and extend the wavelength to cover the whole infrared band has important significance.

An n-type contact layer-B barrier layer-n-type absorption layer (nBn for short) structure based on InAsSb materials is proposed at first at the university of Rochester in 2006. The nBn structure is different from a traditional p-n junction structure, a depletion region is removed from a narrow-bandgap absorption layer to a wide-bandgap semiconductor material through energy band design engineering, generation-recombination related dark current is reduced, meanwhile, a large energy barrier in a conduction band plays a self-passivation role, surface leakage current can be inhibited, dark current of a device is obviously reduced, and working temperature of the device is improved.

In the prior art, a shallow mesa etching technology is usually adopted for the nBn structure, namely, mesa is etched to a barrier layer, so that the surface leakage current can be effectively reduced, but the transverse diffusion current is remarkably increased, and particularly for a device with a small mesa size, when the mesa size is smaller than the transverse diffusion length of a current carrier, crosstalk between adjacent mesas can be caused, and the imaging quality of the device is influenced. Through the deep mesa etching technology, the absorption layer is etched, so that the influence of the transverse diffusion current can be eliminated, the dark current of the device is increased, the device is easy to break down in the test use process, and the reliability of the device is also reduced.

Disclosure of Invention

In order to overcome the defects in the prior art, the utility model aims to provide an inverted 3-5 mu m nBn type InAsSb infrared detector material structure; by improving the structure and adopting an inverted extended wavelength nBn structure, the response wavelength of the infrared detector prepared on the basis of the structure is extended to 5 mu m, and meanwhile, the transverse diffusion current can be reduced under the condition of not increasing the dark current of the infrared detector, so that the performance of the infrared detector is further improved.

In order to achieve the purpose of the utility model, the following technical scheme is provided.

A material structure of an inverted 3-5 mu m nBn type InAsSb infrared detector comprises a top electrode contact layer, an absorption layer, a barrier layer, a bottom electrode contact layer, a buffer layer and a substrate which are sequentially arranged from top to bottom.

Wherein the thickness of the top electrode contact layer is 100 nm-300 nm; preferably, the material of the top electrode contact layer is n-type InAs doped with silicon (Si)_0.81Sb_0.19Single crystal with Si doping concentration of 1X 10¹⁷cm^-3～1×10¹⁸cm^-3。

The thickness of the absorption layer is 2000 nm-3500 nm; preferred materials for the absorber layer are unintentionally doped InAs_0.81Sb_0.19And (3) single crystal.

The thickness of the barrier layer is 100 nm-200 nm, the forbidden bandwidth of the barrier layer material is larger than that of the absorption layer, and the crystal lattice of the barrier layer material is matched with that of the absorption layer material; the material of the barrier layer is preferably an unintentionally doped AlSb single crystal.

The thickness of the bottom electrode contact layer is 200 nm-500 nm; preferably, the material of the bottom electrode contact layer is n-type InAs doped with silicon (Si)_0.81Sb_0.19Single crystal with Si doping concentration of 1X 10¹⁷cm^-3～1×10¹⁸cm^-3。

The thickness of the buffer layer is 100 nm-500 nm; the preferred material for the buffer layer is unintentionally doped GaSb.

The preferred substrate material is n-type GaSb doped with tellurium (Te) at a doping concentration of 1 × 10¹⁷cm^-3～5×10¹⁷cm^-3。

The inverted 3-5 mu m nBn type InAsSb infrared detector material structure can be prepared by a molecular technique epitaxial method in the prior art, and comprises the following steps:

(1) growing a buffer layer on the clean substrate after the oxide is removed;

(2) growing a bottom electrode contact layer on the buffer layer prepared in the step (1);

(3) growing a barrier layer on the bottom electrode contact layer prepared in the step (2);

(4) growing an absorption layer on the barrier layer prepared in the step (3);

(5) and (4) growing a top electrode contact layer on the absorption layer prepared in the step (4) to prepare an inverted 3-5 mu m nBn type InAsSb infrared detector material structure.

And further, etching the material structure, etching the absorption layer to the barrier layer, and preparing the absorption table top.

Advantageous effects

1. The utility model provides an inverted 3-5 mu m nBn type InAsSb infrared detectorThe material structure adopts an inverted nBn structure, so that the transverse diffusion current of the device is effectively reduced under the condition of not increasing the surface leakage current of the device, the dark current of the device is further reduced, and good conditions are created for the subsequent preparation of a high-performance focal plane device; the material adopts InAs with the Sb component of 0.19_0.81Sb_0.19The single crystal extends the response wavelength of the infrared detection material made of the material to 5 μm, covering the entire medium-wave infrared window.

2. The utility model provides an inverted 3-5 mu m nBn type InAsSb infrared detector material structure, and a top electrode contact layer can form good ohmic contact and good carrier transmission effect with a metal electrode.

3. The utility model provides an infrared detector material structure, on the basis of adopting the material structure, a deep mesa preparation technology is adopted to etch an absorption layer to a barrier layer to prepare a mesa, so that the transverse diffusion current of a traditional nBn structure device caused by shallow mesa etching is effectively reduced, and the infrared detector material structure is suitable for detecting mid-band infrared under the condition of high working temperature.

4. The utility model provides a material structure of an inverted 3-5 mu m nBn type InAsSb infrared detector, which utilizes the characteristic that the energy band difference of a heterojunction material mainly falls in a conduction band, uses a conduction band barrier formed by an AlSb material to prevent the conduction of majority carriers, and minority carriers in an absorption layer pass through the barrier through diffusion to form a current response signal; the barrier layer has a large forbidden band width, and the generation-recombination current of the barrier layer is basically negligible, so that the generation-recombination current and the band-to-band tunneling current of a depletion region do not exist.

5. The utility model provides an inverted 3-5 mu m nBn type InAsSb infrared detector material structure, which adopts an AlSb material as a barrier layer to inhibit dark current from being generated, and meanwhile, the AlSb material is a wide bandgap material and hardly absorbs detected medium wave infrared, thereby being beneficial to improving the quantum efficiency of an infrared detector.

Drawings

FIG. 1 is a schematic diagram of the inverted 3-5 μm nBn type InAsSb infrared detector material structure.

Fig. 2 is a schematic structural diagram of an infrared detector in embodiment 3.

FIG. 3 is a J-V curve of the infrared detector A at an operating temperature of 150K in example 3.

FIG. 4 is a J-V curve of the infrared detector B at an operating temperature of 150K in example 3.

Wherein, 1-top electrode contact layer, 2-absorption layer, 3-barrier layer, 4-bottom electrode contact layer, 5-buffer layer, 6-substrate, 7-electrode, 8-passivation layer

Detailed Description

The utility model is described in detail below with reference to the drawings and specific embodiments, but the utility model is not limited thereto.

Example 1

An inverted 3-5 μm nBn type InAsSb infrared detector material structure is shown in figure 1 and sequentially comprises a top electrode contact layer 1, an absorption layer 2, a barrier layer 3, a bottom electrode contact layer 4, a buffer layer 5 and a substrate 6 from top to bottom.

The material of the top electrode contact layer 1 is n-type InAs doped with silicon (Si)_0.81Sb_0.19Single crystal with Si doping concentration of 1X 10¹⁸cm^-3(ii) a The thickness of the top electrode contact layer 1 was 300 nm.

The material of the absorption layer 2 is unintentionally doped InAs_0.81Sb_0.19Single crystal; the thickness of the absorption layer 2 was 3500 nm.

The barrier layer 3 is made of unintentionally doped AlSb single crystal, and the forbidden bandwidth of the barrier layer 3 is larger than that of the absorption layer 2; the thickness of the barrier layer 3 was 200 nm.

The material of the bottom electrode contact layer 4 is Si-doped n-type InAs_0.81Sb_0.19Single crystal with Si doping concentration of 1X 10¹⁸cm^-3(ii) a The thickness of the bottom electrode contact layer 4 was 500 nm.

The buffer layer 5 is made of unintentionally doped GaSb; the thickness of the buffer layer 5 is 500 nm.

The substrate 6 is n-type GaSb (100) doped with Te at a doping concentration of 1 × 10¹⁷cm^-3(ii) a The thickness of the substrate 6 was 500 μm.

A preparation method of the inverted 3-5 μm nBn type InAsSb infrared detector material structure is a molecular technique epitaxy method, and the method is carried out under the vacuum degree of 10^-10The method is carried out in molecular beam epitaxy equipment with more than Torr magnitude, and comprises the following specific steps:

(1) growing a buffer layer 5 on the clean substrate 6 after the oxide is removed;

(2) growing a bottom electrode contact layer 4 on the buffer layer 5 prepared in the step (1);

(3) growing a barrier layer 3 on the bottom electrode contact layer 4 prepared in the step (2);

(4) growing an absorption layer 2 on the barrier layer 3 prepared in the step (3);

(5) and (4) growing a top electrode contact layer 1 on the absorption layer 2 prepared in the step (4) to prepare an inverted 3-5 mu m nBn type InAsSb infrared detector material structure.

Example 2

The material of the top electrode contact layer 1 is Si-doped n-type InAs_0.81Sb_0.19Single crystal with Si doping concentration of 1X 10¹⁷cm^-3(ii) a The thickness of the top electrode contact layer 1 was 100 nm.

The material of the absorption layer 2 is unintentionally doped InAs_0.81Sb_0.19Single crystal; the thickness of the absorption layer 2 was 2000 nm.

The barrier layer 3 is made of unintentionally doped AlSb single crystal, and the forbidden bandwidth of the barrier layer 3 is larger than that of the absorption layer 2; the thickness of the barrier layer 3 was 100 nm.

The bottom electrode contact layer 4 is made of Si-doped n-type InAs_0.81Sb_0.19Single crystal with Si doping concentration of 1X 10¹⁷cm^-3(ii) a The thickness of the bottom electrode contact layer 4 was 200 nm.

The buffer layer 5 is made of unintentionally doped GaSb; the thickness of the buffer layer 5 is 100 nm.

The substrate 6 is made of n-type GaSb (100) doped with Te at a doping concentration of 5 × 10¹⁷cm^-3(ii) a The thickness of the substrate 6 was 500 μm.

A method for preparing the inverted 3-5 μm nBn type InAsSb infrared detector material structure in this embodiment, which is a molecular technique epitaxy method, is performed at a vacuum degree of 10^-10The method is carried out in molecular beam epitaxy equipment with more than Torr magnitude, and comprises the following specific steps:

(5) and (5) growing a top electrode contact layer 1 on the absorption layer 2 prepared in the step (4) to prepare an inverted 3-5 mu m nBn type InAsSb infrared detector material structure.

Experimental example 3

An infrared detector a is prepared on the basis of the material structure prepared in the embodiment 1, and an infrared detector B is prepared on the basis of the material structure prepared in the embodiment 2, and the preparation methods of the infrared detectors are the same and specifically as follows:

by a method combining dry etching and wet etching, firstly, a mesa is etched to a barrier layer 3, etching is carried out on the basis of the material structure prepared in the embodiment 1 to obtain the mesa height of 3.8 microns, etching is carried out on the basis of the material structure prepared in the embodiment 2 to obtain the mesa height of 2.1 microns, and a sample is prepared; sequentially depositing SiO with the thickness of 100nm at the temperature of 120 ℃ by adopting an inductive coupling enhanced chemical vapor deposition (ICPCVD) system₂And Si 300nm thick₃N₄Passivating the sample by the composite film to form a passivation layer 8, wherein SiO is prepared₂By SiH₄、O₂And Ar at gas flow rates of 6.0sccm, 7.5sccm, and 156sccm, respectively, to prepare Si₃N₄By SiH₄、NH₃And Ar, gas flow rates of 6, respectively.0sccm, 8sccm, and 278sccm, physically protecting and electrically insulating the sample surface; etching a metal electrode window by adopting a reactive ion etching system (RIE), evaporating Cr with the thickness of 50nm and Au with the thickness of 250nm by using an electron beam, stripping and ultrasonically cleaning to finish the preparation of an electrode 7, forming ohmic contact, and preparing the infrared detector, wherein the structure of the infrared detector is shown in figure 2, the infrared detector comprises a substrate 6, a buffer layer 5, a bottom electrode contact layer 4, a barrier layer 3, an absorption layer 2 and a top electrode contact layer 1 which are sequentially arranged from bottom to top, and the surface of a table board obtained by etching is SiO₂And Si₃N₄And a metal electrode 7 is arranged on the passivation layer 8 of the composite film at the corresponding position of the top electrode contact layer 1 and the bottom electrode contact layer 4.

For the infrared detectors A and B, I-V test was performed by using a KEYSIGHT B1500A semiconductor analyzer, and J-V curves of the infrared detectors were calculated, and the results are shown in FIG. 3 and FIG. 4, where FIG. 3 is a J-V curve of the infrared detector A at a 150K operating temperature under a dark background, and shows that the infrared detector has a dark current density of 3.5 × 10 at a 150K operating temperature and a 500mV bias voltage^-4A/cm ². FIG. 4 is a J-V curve of infrared detector B at a 150K operating temperature against a dark background, showing an infrared detector dark current density of 8.7X 10 against a 500mV bias voltage at a 150K operating temperature^-5A/cm²。

As can be seen from the results shown in fig. 3 and 4, compared with a medium wave InSb pn junction infrared detector, the dark current of the infrared detector is greatly reduced, the working temperature of the infrared detector is increased, and the requirement of an infrared detector assembly on refrigeration is reduced, so that the overall size, weight, power consumption and cost are reduced, the reliability of the system is improved, and the service life of the system is prolonged.

Claims

1. An inverted 3-5 mu m nBn type InAsSb infrared detector material structure is characterized in that: the material structure comprises a top electrode contact layer (1), an absorption layer (2), a barrier layer (3), a bottom electrode contact layer (4), a buffer layer (5) and a substrate (6) which are sequentially arranged from top to bottom;

and etching the material structure, etching the absorption layer to the barrier layer, and preparing the absorption table top.

2. The inverted 3-5 μm nBn-type InAsSb infrared detector material structure of claim 1, wherein: the thickness of the top electrode contact layer (1) is 100 nm-300 nm.

3. The inverted 3-5 μm nBn-type InAsSb infrared detector material structure of claim 1, wherein: the thickness of the absorption layer (2) is 2000nm to 3500 nm.

4. The inverted 3-5 μm nBn-type InAsSb infrared detector material structure of claim 1, wherein: the thickness of the barrier layer (3) is 100nm to 200 nm.

5. The inverted 3-5 μm nBn-type InAsSb infrared detector material structure of claim 1, wherein: the thickness of the bottom electrode contact layer (4) is 200 nm-500 nm.

6. The inverted 3-5 μm nBn-type InAsSb infrared detector material structure of claim 1, wherein: the thickness of the buffer layer (5) is 100nm to 500 nm.

7. The inverted 3-5 μm nBn-type InAsSb infrared detector material structure of claim 1, wherein: the thickness of the top electrode contact layer (1) is 100 nm-300 nm;

the thickness of the absorption layer (2) is 2000 nm-3500 nm;

the thickness of the barrier layer (3) is 100 nm-200 nm;

the thickness of the bottom electrode contact layer (4) is 200 nm-500 nm;

the thickness of the buffer layer (5) is 100nm to 500 nm.