Preparation method of tellurium-cadmium-mercury double-layer component heterostructure

Abstract

The invention relates to a preparation method of a tellurium-cadmium-mercury double-layer component heterostructure. The preparation method comprises the following steps: forming a doped region on the surface of a tellurium-cadmium-mercury material through ion implantation; impurity distribution is adjusted through impurity distribution regulation and control annealing; growing a cadmium telluride film on the surface of the mercury cadmium telluride; performing diffusion annealing to cause mutual diffusion between cadmium telluride and mercury cadmium telluride, and removing the cadmium telluride film to form a mercury cadmium telluride material with a double-layer component heterostructure; the preparation difficulty of the HgCdTe double-layer component heterostructure is reduced, a good passivation structure can be formed on the HgCdTe surface, the matching of the component heterostructure and the PN junction relative position is easy to realize, and the dark current of the HgCdTe infrared detector is inhibited.

Description

Technical Field

[0001] The present invention relates to the technical field of mercury cadmium telluride infrared detectors, and relates to a preparation method for a mercury cadmium telluride double-layer composition heterostructure. Background Art

[0002] Mercury cadmium telluride (Hg x Cd 1-x Te) is a ternary compound semiconductor. By adjusting the Hg component in the material, the bandgap of the material can vary within the range of 0 - 1.45 eV, and the absorption range can cover the entire infrared band. Mercury cadmium telluride is a direct bandgap semiconductor material with a high absorption coefficient; it is easy to adjust its carrier concentration by doping. Based on the above characteristics, mercury cadmium telluride has occupied an important position in the field of infrared materials and devices since its discovery. Mercury cadmium telluride infrared detectors have also been widely used in fields such as security, meteorology, and environment, and are one of the main technical solutions for high-performance infrared detectors.

[0003] Currently, the device structures of commercially available mercury cadmium telluride infrared detectors mainly include n-on-p and p-on-n. Since the doping concentration of the n-type mercury cadmium telluride absorption layer is easy to control, and its minority carrier lifetime can be controlled at a relatively high level, the p-on-n structure mercury cadmium telluride infrared detector has lower dark current and better performance, and has become an important technical path for high-performance mercury cadmium telluride infrared detectors.

[0004] The double-layer composition heterostructure is one of the key structural designs of p-on-n type mercury cadmium telluride detectors. It refers to preparing two mercury cadmium telluride thin films with different compositions in the mercury cadmium telluride material. The mercury cadmium telluride thin film with a high composition and wide bandgap is located on the surface, which helps to achieve good surface passivation of the mercury cadmium telluride detector. At the same time, by matching the relative positions of the double-layer composition suppression structure and the PN junction, the width of the PN junction barrier can be effectively increased, and the tunneling current can be reduced. Therefore, the double-layer composition heterostructure is an effective method for suppressing the dark current of p-on-n type mercury cadmium telluride infrared detectors and has become one of the key steps in the preparation of p-on-n type mercury cadmium telluride infrared detectors.

[0005] Currently, the preparation methods for mercury cadmium telluride double-layer composition heterojunctions mainly involve growing mercury cadmium telluride thin films with different compositions by molecular beam epitaxy or liquid phase epitaxy methods, and realizing the preparation of the PN junction through in-situ growth doping or ion implantation doping. These two preparation methods have high requirements for process control during the material growth process, and the material preparation process is relatively complex. Summary of the Invention

[0006] The object of the present invention is to provide a preparation method for a mercury cadmium telluride double-component heterostructure. By innovatively using doping and diffusion methods, the preparation difficulty of the mercury cadmium telluride double-component heterostructure is reduced. Meanwhile, a good passivation structure can be formed on the surface of mercury cadmium telluride, and it is easy to achieve the matching of the relative positions of the component heterostructure and the PN junction, thereby suppressing the dark current of the mercury cadmium telluride infrared detector.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A preparation method for a mercury cadmium telluride double-component heterostructure includes the following steps:

[0009] Step 1: Perform ion implantation of a dopant on the mercury cadmium telluride material to obtain a mercury cadmium telluride material containing the dopant;

[0010] Step 2: Anneal the mercury cadmium telluride material containing the dopant to regulate the impurity distribution;

[0011] Step 3: Grow a cadmium telluride thin film on the mercury cadmium telluride material containing the dopant;

[0012] Step 4: Perform diffusion annealing on the mercury cadmium telluride material containing the dopant on which the cadmium telluride thin film has been grown and which has undergone regulated annealing;

[0013] Step 5: Remove the cadmium telluride thin film on the mercury cadmium telluride material after diffusion annealing.

[0014] The dopant implanted in Step 1 is phosphorus or arsenic or antimony or bismuth.

[0015] The temperature for annealing to regulate the impurity distribution in Step 2 is 200°C to 500°C.

[0016] The temperature for diffusion annealing in Step 4 is 200°C to 500°C.

[0017] The growth methods of the cadmium telluride thin film in Step 3 include thermal evaporation, electron beam evaporation, molecular beam epitaxy, magnetron sputtering, and close-spaced sublimation.

[0018] The thickness of the cadmium telluride thin film in Step 3 is 0.01 μm to 5 μm.

[0019] The order of Step 2 and Step 3 can be swapped.

[0020] In Step 5, the cadmium telluride thin film is removed by wet etching or dry etching.

[0021] During the annealing for regulating the impurity distribution in Step 2 and the diffusion annealing in Step 4, a protective atmosphere can be added to the mercury cadmium telluride material. The atmosphere is hydrogen or nitrogen or argon or mercury vapor, or the atmosphere is a combination of hydrogen and mercury vapor; or the atmosphere is a combination of nitrogen and mercury vapor; or the atmosphere is a combination of argon and mercury vapor.

[0022] The advantages of the present invention are as follows: 1. By adjusting the doping and diffusion processes, the present invention realizes the preparation of a double-layer heterostructure based on a single-component mercury cadmium telluride material, reducing the difficulty of growing mercury cadmium telluride materials and preparing double-layer component heterostructures; 2. The mercury cadmium telluride double-layer heterostructure prepared by the method of the present invention can achieve the matching of the relative positions of the component heterostructure and the PN junction, suppressing the dark current of the mercury cadmium telluride infrared detector. Description of the Drawings

[0023] Figure 1 is a schematic flow chart of the preparation method of the present invention;

[0024] Figure 2 is the mercury cadmium telluride double-layer component heterostructure prepared in Example 1 of the present invention;

[0025] Figure 3 is the mercury cadmium telluride double-layer component heterostructure prepared in Example 2 of the present invention. Detailed Embodiments

[0026] The present invention will be further described below with reference to the drawings. The drawings are only for illustrative purposes and should not be construed as a limitation of this patent.

[0027] To describe this embodiment more concisely, some components that are well known to those skilled in the art but not relevant to the main content of this creation will be omitted in the drawings or description. Additionally, for ease of expression, some components in the drawings will be omitted, enlarged, or reduced, but this does not represent the actual size or entire structure of the product.

[0028] The present invention discloses a preparation method for a mercury cadmium telluride double-layer component heterostructure, as Figure 1 shown, including the following steps:

[0029] Step 1: Perform ion implantation of a dopant on the mercury cadmium telluride material to obtain a mercury cadmium telluride material containing the dopant; the dopant implanted is phosphorus or arsenic or antimony or bismuth.

[0030] Step 2: Perform impurity profile control annealing on the mercury cadmium telluride material containing the dopant; the annealing temperature range is 200°C to 500°C.

[0031] Step 3: Grow a cadmium telluride thin film on the mercury cadmium telluride material containing the dopant; the thickness of the cadmium telluride thin film is 0.01 μm to 5 μm. The growth methods include thermal evaporation, electron beam evaporation, molecular beam epitaxy, magnetron sputtering, and close-spaced sublimation.

[0032] Step 4: Perform diffusion annealing on the mercury cadmium telluride material containing the dopant on which the cadmium telluride thin film has been grown and which has undergone profile control annealing; the annealing temperature is 200°C to 500°C.

[0033] Step Five: Remove the cadmium telluride thin film on the mercury cadmium telluride material after diffusion annealing. The cadmium telluride thin film is removed by wet etching or dry etching.

[0034] In the above steps, the order of Step Two and Step Three can be swapped, or cadmium telluride thin film can be grown on the mercury cadmium telluride material containing dopant first, and then impurity distribution control annealing is carried out.

[0035] During the impurity distribution control annealing in Step Two and the diffusion annealing in Step Four, a protective atmosphere can be added to the mercury cadmium telluride material. The atmosphere is hydrogen or nitrogen or argon or mercury vapor, or the atmosphere is a combination of hydrogen and mercury vapor; or the atmosphere is a combination of nitrogen and mercury vapor; or the atmosphere is a combination of argon and mercury vapor. The protective atmosphere can be one or a combination of several of hydrogen, nitrogen, argon, and mercury vapor.

[0036] Example One:

[0037] Select a mercury cadmium telluride thin film sample grown on a cadmium zinc telluride substrate by liquid phase epitaxy method. The mercury component of the mercury cadmium telluride material is 0.221, and the surface of the material is cleaned with an organic reagent.

[0038] Step One: Perform arsenic ion implantation on the mercury cadmium telluride material. The implantation energy is 350 keV, and the dose is 3×10 14 cm -2 ;

[0039] Step Two: Put the mercury cadmium telluride material into a quartz tube, add mercury to the quartz tube, and use a vacuum pump to evacuate the air in the quartz tube to achieve a vacuum degree ≤ 1×10 -3 Pa. Seal the quartz tube at high temperature to seal the mercury cadmium telluride material in a vacuum quartz tube containing mercury. Put the material together with the quartz tube into a tube furnace and anneal for 2 hours. The temperature of the tube furnace is controlled at 450°C.

[0040] Step Three: Take out the annealed mercury cadmium telluride material and clean it. Use the thermal evaporation method to grow a 0.5 μm cadmium telluride thin film on the surface of the material.

[0041] Step Four: As in Step Two, encapsulate the mercury cadmium telluride material with the cadmium telluride thin film grown in Step Three in a quartz tube, put the material together with the quartz tube into a tube furnace and anneal for 8 hours. The temperature of the tube furnace is controlled at 350°C.

[0042] Step Five: Take out the annealed mercury cadmium telluride material, clean the surface, and etch the material with bromo-methanol etching solution for 0.6 μm to remove the cadmium telluride thin film, obtaining a mercury cadmium telluride material with a double-layer component heterostructure. The material composition and doping distribution are as Figure 2 shown.

[0043] Example Two:

[0044] A mercury cadmium telluride thin film sample grown on a cadmium zinc telluride substrate by liquid phase epitaxy is selected. The mercury component of the mercury cadmium telluride material is 0.237, and the material surface is cleaned with an organic reagent.

[0045] Step 1: Perform arsenic ion implantation on the mercury cadmium telluride material. The implantation energy is 350 keV, and the dose is 1×10 14 cm -2 ;

[0046] Step 2: Place the mercury cadmium telluride material in a mercury-rich annealing furnace. Evacuate the vacuum chamber of the furnace to below 5 Pa, introduce hydrogen to normal pressure, repeat this operation twice, then stabilize the hydrogen pressure in the chamber at 2 atm, turn on the heating to 420 °C, maintain for 6 hours, and then cool down.

[0047] Step 3: Take out the annealed mercury cadmium telluride material and clean it. Use the electron beam evaporation method to grow a 0.3 μm cadmium telluride thin film on the material surface.

[0048] Step 4: As in Step 2, place the mercury cadmium telluride material with the cadmium telluride thin film grown in Step 3 in a mercury-rich annealing furnace, turn on the heating to 350 °C, maintain for 4 hours, and then cool down.

[0049] Step 5: Take out the annealed mercury cadmium telluride material, clean the surface, use a bromine methanol etching solution to etch the material by 0.4 μm to remove the cadmium telluride thin film, and obtain a mercury cadmium telluride material with a double-layer component heterostructure. The material components and doping distributions are as Figure 3 shown.

[0050] In summary, the above is only the preferred embodiment of the present invention and is not used to limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made according to the content of the patent application scope of the present invention should fall within the technical scope of the present invention.

Claims

1. A method for preparing a mercury cadmium telluride double-layer component heterostructure, characterized in that: The following steps are included: Step 1, performing ion implantation of a dopant into the mercury cadmium telluride material to obtain a mercury cadmium telluride material containing a dopant; Step 2, performing impurity distribution control annealing on the mercury cadmium telluride material containing the dopant; Step 3, growing a cadmium telluride thin film on the mercury cadmium telluride material containing a dopant; Step 4, diffusing and debonding the HgCdTe material containing the dopant after the cadmium telluride film is grown and the debonding is regulated; Step 5, removing the cadmium telluride film on the HgCdTe material after diffusion and withdrawal.

2. The preparation method according to claim 1, characterized in that: The dopant implanted in step 1 is phosphorus, arsenic, antimony or bismuth.

3. The preparation method according to claim 1, characterized in that: In step 2, the temperature of the impurity distribution control annealing is 200° C. to 500° C.

4. The preparation method according to claim 1, characterized in that: The temperature of the diffusion annealing in step 4 is 200°C to 500°C.

5. The preparation method according to claim 1, characterized in that: The growth method of the cadmium telluride film in step three includes thermal evaporation, electron beam evaporation, molecular beam epitaxy, magnetron sputtering and close-space sublimation.

6. The preparation method according to claim 1, characterized in that: In step 3, the thickness of the cadmium telluride film is 0.01 μm to 5 μm.

7. The preparation method according to claim 1, characterized in that: The order of steps 2 and 3 can be reversed.

8. The preparation method according to claim 1, characterized in that: Step 5: removing the cadmium telluride film by wet etching or etching.

9. The preparation method according to claim 1, characterized in that: During the impurity distribution control annealing in step 2 and the diffusion annealing in step 4, the mercury cadmium telluride material can be protected by a protective atmosphere, which is hydrogen, nitrogen, argon or mercury vapor, or a combination of hydrogen and mercury vapor; or a combination of nitrogen and mercury vapor; or a combination of argon and mercury vapor.

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