Tellurium-cadmium-mercury electrochemical oxidation liquid and application thereof

Abstract

The invention discloses tellurium-cadmium-mercury electrochemical oxidation liquid and application thereof. The tellurium-cadmium-mercury electrochemical oxidation liquid can be used for passivating the surface of tellurium-cadmium-mercury. The oxidation liquid has the advantages that the oxidized tellurium-cadmium-mercury surface has less surface charge density (Nf), and the effective minority carrier lifetime of the oxidized tellurium-cadmium-mercury is longer. By taking a medium-wave tellurium-cadmium-mercury material (lambda c is about 5.4 microns) as an example, the surface Nf of a tellurium-cadmium-mercury wafer treated by using the oxidation liquid can be as low as 2.48 * 10 < 10 > cm <-2 > q <-1 > V <-1 >, and the surface charge density of the tellurium-cadmium-mercury wafer is generally one order of magnitude smaller than that of a conventional oxidized tellurium-cadmium-mercury material. The effective minority carrier lifetime of the tellurium-cadmium-mercury wafer reaches 1.2 [mu] s, which is about one time longer than the average effective minority carrier lifetime of the tellurium-cadmium-mercury wafer subjected to conventional oxidation treatment.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of infrared photoelectric detectors, and in particular to a mercury cadmium telluride electrochemical oxidation solution and application thereof. Background Art

[0002] During the formation of bulk material HgCdTe wafers, the wafer surface needs to be passivated. Conventional passivation treatment uses an alkaline inorganic oxidizing solution containing potassium ions as the main component for electrochemical oxidation. Potassium ions may enter the HgCdTe crystals as impurities, forming recombination centers, increasing the recombination rate of carriers, thereby reducing the minority carrier lifetime. At the same time, the surface charge density of HgCdTe will also be relatively large, which is not conducive to improving the performance of HgCdTe detectors.

[0003] Therefore, how to avoid the influence of potassium ions on material properties, reduce the surface charge density of the passivation layer, and increase the effective minority carrier lifetime of mercury cadmium telluride has become a technical problem that needs to be solved. Summary of the invention

[0004] The purpose of the present invention is to provide a mercury cadmium telluride electrochemical oxidation solution and its application, mainly to solve the problem of how to avoid the influence of potassium ions on material properties, reduce the surface charge density of the passivation layer, and increase the effective minority carrier lifetime of mercury cadmium telluride in the above-mentioned prior art.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a mercury cadmium telluride electrochemical oxidation solution, characterized in that the mercury cadmium telluride electrochemical oxidation solution is composed of tetramethylammonium hydroxide, hydrogen peroxide and ethylene glycol, and the proportions of each component are as follows: tetramethylammonium hydroxide 100g / L~200g / L, hydrogen peroxide 100g / L~150g / L, and the balance is ethylene glycol.

[0006] An application of a mercury cadmium telluride electrochemical oxidation solution, using the above mercury cadmium telluride electrochemical oxidation solution, is characterized by the following specific steps:

[0007] Step 1, pour the prepared mercury cadmium telluride electrochemical oxidation solution into a culture dish and electroplate at room temperature;

[0008] Step 2, placing the mercury cadmium telluride wafer in an oxidizing solution, placing an anode tungsten needle on the mercury cadmium telluride wafer, and placing a cathode platinum sheet in the oxidizing solution;

[0009] Step 3, constant current 0.1-0.5 mA, the oxidation voltage reaches 20V and the power is turned off;

[0010] Step 4, take out the mercury cadmium telluride, rinse it in deionized water for 3 minutes, blow dry it with nitrogen, and store it in a drying oven.

[0011] In view of the above technical features, the present invention has the following beneficial effects:

[0012] 1. The present invention discloses a mercury cadmium telluride surface electrochemical oxidation solution, which uses a strong organic base to replace the inorganic base component of the conventional oxidation solution, so as to avoid the influence of potassium ions on the material properties. Compared with the passivation layer grown by the inorganic base oxidation solution, the passivation layer grown by the oxidation solution can reduce the surface charge density and increase the effective minority carrier lifetime of mercury cadmium telluride. Specifically, the mercury cadmium telluride surface oxidized by the present invention has a smaller charge density, which is one order of magnitude smaller. The mercury cadmium telluride oxidized by the present invention has a longer effective minority carrier lifetime, and the effective minority carrier lifetime of medium-wave mercury cadmium telluride is about 1 times higher than that of mercury cadmium telluride grown by the inorganic oxidation solution. DETAILED DESCRIPTION

[0013] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0014] Specific embodiment 1 provides a mercury cadmium telluride electrochemical oxidation solution, which is composed of tetramethylammonium hydroxide (C 4 H 13 NO), hydrogen peroxide (H 2 O 2 ) and ethylene glycol (C 2 H 6 O 2 ), the proportions of each component are as follows: tetramethylammonium hydroxide 100g / L~200g / L, hydrogen peroxide 100g / L~150g / L, and the balance is ethylene glycol.

[0015] An application of a mercury cadmium telluride electrochemical oxidation solution, using the above mercury cadmium telluride electrochemical oxidation solution, is characterized by the following specific steps:

[0016] Step 1, pour the prepared mercury cadmium telluride electrochemical oxidation solution into a culture dish and electroplate at room temperature;

[0017] Step 2, placing the mercury cadmium telluride wafer in an oxidizing solution, placing an anode tungsten needle on the mercury cadmium telluride wafer, and placing a cathode platinum sheet in the oxidizing solution;

[0018] Step 3, constant current 0.1-0.5 mA, the oxidation voltage reaches 20V and the power is turned off;

[0019] Step 4, take out the mercury cadmium telluride, rinse it in deionized water for 3 minutes, blow dry it with nitrogen, and store it in a drying oven.

[0020] The invention discloses a mercury cadmium telluride electrochemical oxidation solution, which can be used for passivation of the mercury cadmium telluride surface. The advantages of the oxidation solution are that the mercury cadmium telluride surface after oxidation has a lower surface charge density (N f), the effective minority carrier lifetime of HgCdTe after oxidation is also longer. Taking the medium-wave HgCdTe material (λc about 5.4um) as an example, the surface N f Can be as low as 2.48×10 10 cm -2 q -1 V -1 , the surface of HgCdTe treated with conventional oxidizing solution (mainly potassium hydroxide) f About 1×10 10 cm -2 q -1 V -1 , which is one order of magnitude smaller than the surface charge density of HgCdTe with conventional oxidation. The effective minority carrier lifetime of HgCdTe reaches 1.2μs, which is about 1 times higher than the average effective minority carrier lifetime of HgCdTe wafers with conventional oxidation treatment.

[0021] The specific effects of the present invention are as follows:

[0022] Four medium-wave HgCdTe wafers were treated with the electrochemical oxidation solution of the present invention and a conventional electrochemical oxidation solution respectively, and then their minority carrier lifetimes were measured and the results were compared.

[0023] Table 1 Related parameters of four HgCdTe wafers

[0024]

[0025]

[0026] Embodiment 1

[0027] The electrochemical oxidation liquid is an organic oxidation liquid, i.e., 100 g / L of tetramethylammonium hydroxide, 100 g / L of hydrogen peroxide, and the balance is ethylene glycol. The conventional electrochemical oxidation liquid is an inorganic oxidation liquid, i.e., 400-450 ml of ethylene glycol, 50-100 ml of deionized water, and 1-3 g of potassium hydroxide. Two oxidation liquids are prepared respectively, and the same mercury cadmium telluride wafer is oxidized. Subsequently, the minority carrier lifetime of the mercury cadmium telluride wafer is measured. The measuring equipment is the minority carrier measuring instrument model WT-2000MCT of Semilab Company of Hungary. The measurement results are as follows:

[0028]

[0029] Embodiment 2

[0030] The electrochemical oxidation liquid is an organic oxidation liquid, i.e. 150g / L tetramethylammonium hydroxide, 125g / L hydrogen peroxide, and the balance is ethylene glycol. The conventional electrochemical oxidation liquid is an inorganic oxidation liquid, i.e. 400-450ml ethylene glycol, 50-100ml deionized water, and 1-3g potassium hydroxide. Two oxidation liquids are prepared respectively, and the same mercury cadmium telluride wafer is oxidized. Then, the minority carrier lifetime of the mercury cadmium telluride wafer is measured. The measuring equipment is the minority carrier measuring instrument model WT-2000MCT of Semilab Company, Hungary. The measurement results are as follows:

[0031]

[0032] Embodiment 3

[0033] The electrochemical oxidation liquid is an organic oxidation liquid, i.e. 200g / L tetramethylammonium hydroxide, 150g / L hydrogen peroxide, and the balance is ethylene glycol. The conventional electrochemical oxidation liquid is an inorganic oxidation liquid, i.e. 400-450ml ethylene glycol, 50-100ml deionized water, and 1-3g potassium hydroxide. Two oxidation liquids are prepared respectively, and the same mercury cadmium telluride wafer is oxidized, and then the minority carrier lifetime of the mercury cadmium telluride wafer is measured. The measuring equipment is the minority carrier measuring instrument model WT-2000MCT of Semilab Company, Hungary. The measurement results are as follows:

[0034]

[0035] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A mercury cadmium telluride electrochemical oxidation solution, characterized in that: The mercury cadmium telluride electrochemical oxidation solution is composed of tetramethylammonium hydroxide, hydrogen peroxide and ethylene glycol, and the proportions of each component are as follows: tetramethylammonium hydroxide 100g / L~200g / L, hydrogen peroxide 100g / L~150g / L, and the balance is ethylene glycol.

2. An application of a mercury cadmium telluride electrochemical oxidation solution, using the mercury cadmium telluride electrochemical oxidation solution according to claim 1, characterized in that: The specific steps are as follows: Step 1, pour the prepared mercury cadmium telluride electrochemical oxidation solution into a culture dish and electroplate at room temperature; Step 2, placing the mercury cadmium telluride wafer in an oxidizing solution, placing an anode tungsten needle on the mercury cadmium telluride wafer, and placing a cathode platinum sheet in the oxidizing solution; Step 3, constant current 0.1-0.5 mA, the oxidation voltage reaches 20V and the power is turned off; Step 4, take out the mercury cadmium telluride, rinse it in deionized water for 3 minutes, blow dry it with nitrogen, and store it in a drying oven.

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