An inverted 3μm~4.2μm nBn-type InAsSb infrared detector material and its preparation method

Abstract

The present invention relates to an inverted 3μm - 4.2μm nBn-type InAsSb infrared detector material and a preparation method thereof, belonging to the technical field of optoelectronic materials and devices. The structure of the material from top to bottom is successively a top electrode contact layer, an absorption layer, a barrier layer, a bottom electrode contact layer, a buffer layer and a substrate; it is prepared by molecular beam epitaxy. The material adopts an inverted nBn structure, which can effectively reduce the lateral diffusion current of the device without increasing the surface leakage current of the device, thereby reducing the dark current of the device; by setting the composition of the Sb component in the material, the absorption wavelength is ensured to be in the 3μm - 4.2μm infrared mid-band of the atmospheric window; the barrier layer of the material uses unintentionally doped AlAs 0.08 Sb 0.92 single crystal as the material to form a conduction band barrier to prevent the conduction of majority carriers, and there is no generation-recombination current and interband tunneling current in the depletion region.

Description

Technical Field

[0001] The invention relates to an inverted 3μm-4.2μm nBn-type InAsSb infrared detector material and a preparation method thereof, belonging to the technical field of optoelectronic materials and devices. Background Art

[0002] In 2006, the University of Rochester in the United States first proposed an n-type contact layer-B barrier layer-n-type absorption layer (abbreviated as nBn) structure based on InAsSb materials. The nBn structure is different from the traditional pn junction structure. Through energy band design engineering, the depletion region is removed from the narrow bandgap absorption layer to the wide bandgap semiconductor material, reducing the generation-recombination related dark current. At the same time, the large energy barrier in the conduction band plays a self-passivation role to suppress the surface leakage current, significantly reduce the device dark current, and increase the device operating temperature.

[0003] In the prior art, the nBn structure usually adopts shallow mesa etching technology, that is, the mesa is etched to the B barrier layer, which can effectively reduce the surface leakage current but significantly increase the lateral diffusion current. Especially for devices with small mesa size, when the mesa size is smaller than the carrier lateral diffusion length, it will cause crosstalk between adjacent mesas, affecting the imaging quality of the device. Through deep mesa etching technology, the absorption layer is cut open, which can eliminate the influence of the above lateral diffusion current, but it will increase the dark current of the device. At the same time, the device is more likely to break down during testing and use, and the reliability of the device will also be reduced. Summary of the invention

[0004] In order to overcome the defects of the prior art, one of the objects of the present invention is to provide an inverted 3μm~4.2μmnBn-type InAsSb infrared detector material. The infrared detector using the material can effectively reduce the lateral diffusion current of the device without increasing the surface leakage current of the device, thereby reducing the dark current of the device.

[0005] A second object of the present invention is to provide a method for preparing an inverted 3μm-4.2μm nBn-type InAsSb infrared detector material.

[0006] To achieve the purpose of the present invention, the following technical solutions are provided.

[0007] An inverted 3μm-4.2μm nBn-type InAsSb infrared detector material, the structure of the material from top to bottom is a top electrode contact layer, an absorption layer, a barrier layer, a bottom electrode contact layer, a buffer layer and a substrate.

[0008] The material of the top electrode contact layer is n-type InAs doped with silicon (Si). 0.91 Sb 0.09 Single crystal; Si doping concentration is 1×10 17 cm-3 ~1×10 18 cm -3 The thickness of the top electrode contact layer is preferably 100 nm to 300 nm.

[0009] The material of the absorption layer is unintentionally doped InAs 0.91 Sb 0.09 The thickness of the absorption layer is preferably 2000nm to 3500nm.

[0010] The barrier layer is made of unintentionally doped AlAs. 0.08 Sb 0.92 The single crystal, the bandgap of the barrier layer material is greater than the bandgap of the absorption layer, and the lattice matches the lattice of the absorption layer material. Preferably, the thickness of the barrier layer is 100nm to 200nm.

[0011] The material of the bottom electrode contact layer is n-type InAs doped with silicon (Si). 0.91 Sb 0.09 Single crystal, Si doping concentration is 1×10 17 cm -3 ~1×10 18 cm -3 The thickness of the bottom electrode contact layer is preferably 200 nm to 500 nm.

[0012] The material of the buffer layer is unintentionally doped GaSb. The thickness of the buffer layer is preferably 50 nm to 200 nm.

[0013] The substrate material is n-type GaSb doped with tellurium (Te), and the Te doping concentration is 1×10 17 ~5×10 17 cm -3 .

[0014] A method for preparing an inverted 3μm-4.2μm nBn type InAsSb infrared detector material according to the present invention, the method is a molecular epitaxy method, the method is carried out under a vacuum degree of 10 -10 The specific steps are as follows:

[0015] (1) growing a buffer layer on a clean substrate after removing oxide;

[0016] (2) growing a bottom electrode contact layer on the buffer layer prepared in step (1);

[0017] (3) growing a barrier layer on the bottom electrode contact layer obtained in step (2);

[0018] (4) growing an absorption layer on the barrier layer prepared in step (3);

[0019] (5) Growing a top electrode contact layer on the absorption layer obtained in step (4) to prepare an inverted 3μm-4.2μm nBn-type InAsSb infrared detector material.

[0020] Beneficial Effects

[0021] 1. The present invention provides an inverted 3μm-4.2μm nBn-type InAsSb infrared detector material. The material adopts an inverted nBn structure, which effectively reduces the lateral diffusion current of the device without increasing the surface leakage current of the device, thereby reducing the dark current of the device.

[0022] 2. The present invention provides an inverted 3μm-4.2μm nBn-type InAsSb infrared detector material, wherein the composition of the Sb component is set to ensure that the absorption wavelength is in the 3μm-4.2μm infrared mid-band of the atmospheric window.

[0023] 3. The present invention provides an inverted 3μm-4.2μm nBn-type InAsSb infrared detector material. The material utilizes the characteristic that the energy band difference of the heterojunction material mainly falls in the conduction band, and the barrier layer is made of non-intentionally doped AlAs 0.08 Sb 0.92 The single crystal is used as a material to form a conduction band barrier to prevent the conduction of majority carriers. The minority carriers in the absorption layer (2) diffuse through the barrier to form a current response signal. The band gap width of the barrier layer is relatively large, and its generation-recombination current can be basically ignored, so there is no generation-recombination current in the depletion region and inter-band tunneling current.

[0024] 4. The present invention provides an inverted 3μm-4.2μm nBn-type InAsSb infrared detector material, wherein the barrier layer of the material is unintentionally doped with AlAs 0.08 Sb 0.92 Single crystal can suppress dark current generation. At the same time, due to AlAs 0.08 Sb 0.92 It is a wide bandgap material, and its bandgap width is larger than that of the lattice-matched absorption layer material InAs 0.91 Sb 0.09 , so it has almost no absorption for the detected mid-wave infrared, which helps to improve the quantum efficiency of the infrared detector.

[0025] 5. The present invention provides an inverted 3μm-4.2μm nBn-type InAsSb infrared detector material, the top electrode contact layer of which can form a good ohmic contact with a metal electrode and a good carrier transport effect.

[0026] 6. The present invention provides an inverted 3μm-4.2μm nBn-type InAsSb infrared detector material. The barrier layer of the material can effectively suppress the generation of recombination current, diffusion current and tunneling current. The absorption layer can be etched open and etched to the barrier layer using deep terrace preparation technology, thereby effectively reducing the lateral diffusion current caused by shallow terrace etching in traditional nBn structure devices. The material is suitable for the detection of mid-band infrared under high operating temperature conditions, and creates good conditions for the subsequent preparation of high-performance focal plane devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic structural diagram of an inverted 3μm-4.2μm nBn-type InAsSb infrared detector material according to the present invention.

[0028] Figure 2 This is a schematic diagram of the structure of the infrared detector described in Example 3.

[0029] Figure 3 This is the JV curve of the infrared detector A in Example 3 at an operating temperature of 150K.

[0030] Figure 4 This is the JV curve of the infrared detector B in Example 3 at an operating temperature of 150K.

[0031] Among them, 1 is the top electrode contact layer, 2 is the absorption layer, 3 is the barrier layer, 4 is the bottom electrode contact layer, 5 is the buffer layer, 6 is the substrate, 7 is the electrode, and 8 is the passivation layer. DETAILED DESCRIPTION

[0032] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention.

[0033] Example 1

[0034] An inverted 3μm~4.2μm nBn type InAsSb infrared detector material, such as Figure 1 As shown, the structure of the infrared detector material is, from top to bottom, 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.

[0035] The material of the top electrode contact layer 1 is n-type InAs doped with silicon (Si). 0.91 Sb 0.09 Single crystal; Si doping concentration is 1×10 18 cm -3 ; The thickness of the top electrode contact layer 1 is 300nm.

[0036] The material of the absorption layer 2 is InAs which is not intentionally doped 0.91 Sb 0.09Single crystal, the thickness of the absorption layer 2 is 3500nm.

[0037] The material of the barrier layer 3 is unintentionally doped AlAs. 0.08 Sb 0.92 The barrier layer 3 is a single crystal. The bandgap of the barrier layer 3 material is greater than the bandgap of the absorption layer 2, and the lattice matches the lattice of the absorption layer 2 material. The thickness of the barrier layer 3 is 200 nm.

[0038] The material of the bottom electrode contact layer 4 is n-type InAs doped with Si. 0.91 Sb 0.09 Single crystal; Si doping concentration is 1×10 18 cm -3 ; The thickness of the bottom electrode contact layer 4 is 500nm.

[0039] The material of the buffer layer 5 is non-intentionally doped GaSb; the thickness of the buffer layer 5 is 200 nm.

[0040] The material of the substrate 6 is n-type GaSb (100) doped with Te, and the Te doping concentration is 1×10 17 cm -3 ; The thickness of the substrate 6 is 500μm.

[0041] A method for preparing an inverted 3μm-4.2μm nBn-type InAsSb infrared detector material according to this embodiment, the method is a molecular epitaxy method, the method is carried out under a vacuum degree of 10 -10 The specific steps are as follows:

[0042] (1) growing a buffer layer 5 on a clean substrate 6 after removing oxide;

[0043] (2) growing a bottom electrode contact layer 4 on the buffer layer 5 obtained in step (1);

[0044] (3) growing a barrier layer 3 on the bottom electrode contact layer 4 obtained in step (2);

[0045] (4) growing an absorption layer 2 on the barrier layer 3 prepared in step (3);

[0046] (5) A top electrode contact layer 1 is grown on the absorption layer 2 obtained in step (4) to prepare an inverted 3 μm-4.2 μm nBn-type InAsSb infrared detector material.

[0047] Example 2

[0048] An inverted 3μm~4.2μm nBn type InAsSb infrared detector material, such as Figure 1As shown, the structure of the infrared detector material is, from top to bottom, 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.

[0049] The material of the top electrode contact layer 1 is n-type InAs doped with Si 0.91 Sb 0.09 Single crystal; Si doping concentration is 1×10 17 cm -3 ; The thickness of the top electrode contact layer 1 is 100nm.

[0050] The material of the absorption layer 2 is InAs which is not intentionally doped 0.91 Sb 0.09 Single crystal; the thickness of the absorption layer 2 is 2000nm.

[0051] The material of the barrier layer 3 is unintentionally doped AlAs. 0.08 Sb 0.92 The barrier layer 3 is a single crystal. The bandgap of the barrier layer 3 material is greater than the bandgap of the absorption layer 2 , and the lattice matches the lattice of the absorption layer 2 material. The thickness of the barrier layer 3 is 100 nm.

[0052] The material of the bottom electrode contact layer 4 is n-type InAs doped with Si. 0.91 Sb 0.09 Single crystal; Si doping concentration is 1×10 17 cm -3 ; The thickness of the bottom electrode contact layer 4 is 200nm.

[0053] The material of the buffer layer 5 is non-intentionally doped GaSb; the thickness of the buffer layer 5 is 50 nm.

[0054] The material of the substrate 6 is n-type GaSb (100) doped with Te; the Te doping concentration is 5×10 17 cm -3 ; The thickness of the substrate 6 is 500μm.

[0055] A method for preparing an inverted 3μm-4.2μm nBn-type InAsSb infrared detector material according to this embodiment, the method is a molecular epitaxy method, the method is carried out under a vacuum degree of 10 -10 The specific steps are as follows:

[0056] (1) growing a buffer layer 5 on a clean substrate 6 after removing oxide;

[0057] (2) growing a bottom electrode contact layer 4 on the buffer layer 5 obtained in step (1);

[0058] (3) growing a barrier layer 3 on the bottom electrode contact layer 4 obtained in step (2);

[0059] (4) growing an absorption layer 2 on the barrier layer 3 prepared in step (3);

[0060] (5) A top electrode contact layer 1 is grown on the absorption layer 2 obtained in step (4) to prepare an inverted 3 μm-4.2 μm nBn-type InAsSb infrared detector material.

[0061] Experimental Example 3

[0062] The infrared detector material prepared in Example 1 was used to prepare an infrared detector A, and the infrared detector material prepared in Example 2 was used to prepare an infrared detector B. The preparation methods of the infrared detectors were the same, and were specifically as follows:

[0063] By combining dry etching and wet etching, the table is first etched to the barrier layer 3, and the infrared detector material prepared in Example 1 is used for etching to obtain a table height of 3.8 μm, and the infrared detector material prepared in Example 2 is used for etching to obtain a table height of 2.1 μm, thereby preparing a sample; then, an inductively coupled enhanced chemical vapor deposition (ICPCVD) system is used to sequentially deposit a 100 nm thick SiO2 and a 300 nm thick Si3N4 composite film at a temperature of 120° C. to passivate the sample to form a passivation layer 8, wherein SiO2 is prepared by using SiH4, O 2 and Ar, with gas flow rates of 6.0 sccm, 7.5 sccm and 156 sccm respectively; Si3N4 is prepared by using SiH4, NH3 and Ar, with gas flow rates of 6.0 sccm, 8 sccm and 278 sccm respectively, to provide physical protection and electrical insulation to the sample surface; a reactive ion etching system (RIE) is used to etch the metal electrode window, and then Cr with a thickness of 50 nm and Au with a thickness of 250 nm are evaporated by electron beam evaporation. After stripping and ultrasonic cleaning, the preparation of electrode 7 is completed to form an ohmic contact, and an infrared detector is prepared, the structure of which is shown in FIG. Figure 2 As shown, it includes 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 arranged in sequence from bottom to top, the surface of the table obtained by etching is a SiO2 and Si3N4 composite film passivation layer 8, and metal electrodes 7 are provided on the passivation layer 8 at corresponding positions of the top electrode contact layer 1 and the bottom electrode contact layer 4.

[0064] For infrared detectors A and B, KEYSIGHT's B1500A semiconductor analyzer was used to perform IV testing and calculate the JV curve of the device. The results are as follows: Figure 3 and Figure 4 As shown, Figure 3This is the JV curve of infrared detector A under dark background at 150K operating temperature. It shows that at 150K operating temperature and 500mV bias voltage, the dark current density of the infrared detector is 4×10 - 6 A / cm 2 . Figure 4 This is the JV curve of infrared detector B under dark background at 150K operating temperature. It shows that at 150K operating temperature and 500mV bias voltage, the dark current density of the infrared detector is 8×10 -6 A / cm 2 .

[0065] Depend on Figure 3 and Figure 4 The results show that the dark current of the infrared detector is greatly reduced, the background limit temperature of the infrared detector is improved, and the refrigeration requirements of the infrared detector component are reduced, thereby reducing the overall volume, weight, power consumption and cost, which can improve system reliability and extend system life.

Claims

1. An inverted 3μm-4.2μm nBn-type InAsSb infrared detector material, characterized in that: The structure of the material is, from top to bottom, 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); The material of the top electrode contact layer (1) is n-type InAs doped with silicon (Si) 0.91 Sb 0.09 Single crystal; The material of the absorption layer (2) is unintentionally doped InAs 0.91 Sb 0.09 Single crystal; The material of the barrier layer (3) is unintentionally doped AlAs 0.08 Sb 0.92 Single crystal; The material of the bottom electrode contact layer (4) is n-type InAs doped with Si 0.91 Sb 0.09 Single crystal; The material of the buffer layer (5) is unintentionally doped GaSb; The material of the substrate (6) is tellurium (Te)-doped n-type GaSb.

2. The inverted 3μm-4.2μm nBn-type InAsSb infrared detector material according to claim 1, characterized in that: The doping concentration of Si in the top electrode contact layer (1) is 1×10 17 cm -3 ~1×10 18 cm -3 .

3. The inverted 3μm-4.2μm nBn-type InAsSb infrared detector material according to claim 1, characterized in that: The doping concentration of Si in the bottom electrode contact layer (4) is 1×10 17 cm -3 ~1×10 18 cm -3 .

4. The inverted 3μm-4.2μm nBn-type InAsSb infrared detector material according to claim 1, characterized in that: The doping concentration of Te in the substrate (6) is 1×10 17 ~5×10 17 cm -3 .

5. The inverted 3μm-4.2μm nBn-type InAsSb infrared detector material according to claim 1, characterized in that: The doping concentration of Si in the top electrode contact layer (1) is 1×10 17 cm -3 ~1×10 18 cm -3 ; The doping concentration of Si in the bottom electrode contact layer (4) is 1×10 17 cm -3 ~1×10 18 cm -3 ; The doping concentration of Te in the substrate (6) is 1×10 17 ~5×10 17 cm -3 .

6. The inverted 3μm-4.2μm nBn-type InAsSb infrared detector material according to claim 1, characterized in that: The thickness of the top electrode contact layer (1) is 100nm to 300nm; The thickness of the absorption layer (2) is 2000nm to 3500nm; The thickness of the barrier layer (3) is 100 nm to 200 nm; The thickness of the bottom electrode contact layer (4) is 200nm to 500nm; The thickness of the buffer layer (5) is 50 nm to 200 nm.

7. The inverted 3μm-4.2μm nBn-type InAsSb infrared detector material according to claim 5, characterized in that: The thickness of the top electrode contact layer (1) is 100nm to 300nm; The thickness of the absorption layer (2) is 2000nm to 3500nm; The thickness of the barrier layer (3) is 100 nm to 200 nm; The thickness of the bottom electrode contact layer (4) is 200nm to 500nm; The thickness of the buffer layer (5) is 50 nm to 200 nm.

8. A method for preparing an inverted 3μm-4.2μm nBn-type InAsSb infrared detector material according to any one of claims 1 to 7, characterized in that: The method is a molecular epitaxy method, in which the vacuum degree is 10 -10 The specific steps are as follows: (1) growing a buffer layer (5) on a clean substrate (6) after removing oxide; (2) growing a bottom electrode contact layer (4) on the buffer layer (5) prepared in step (1); (3) growing a barrier layer (3) on the bottom electrode contact layer (4) obtained in step (2); (4) growing an absorption layer (2) on the barrier layer (3) obtained in step (3); (5) Growing a top electrode contact layer (1) on the absorption layer (2) obtained in step (4) to prepare an inverted 3 μm-4.2 μm nBn-type InAsSb infrared detector material.

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