High-resistance cadmium telluride crystal doping method and application thereof

Abstract

The invention provides a high-resistance cadmium telluride crystal doping method and application thereof. The high-resistance cadmium telluride crystal doping method comprises the following steps: selecting a high-purity cadmium telluride single crystal as a raw material; selecting one or more doping elements to prepare a doping source; putting the doping source into a vacuum melting furnace for heating treatment; growing a cadmium telluride single crystal from the melt; carrying out annealing treatment on the grown cadmium telluride single crystal so as to eliminate defects and stress in the growth process; according to the method, doping elements are uniformly distributed in the cadmium telluride crystal by controlling the proportion of a doping source and the smelting process, and a melting growth method is adopted, so that the operation process is simple, and industrial production is easy to realize; the obtained high-resistance cadmium telluride crystal has good stability, is suitable for long-term use in the fields of photoelectric devices, infrared detectors and the like, and has wide market prospects.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a high-resistance cadmium telluride crystal doping method and application thereof. Background Art

[0002] Cadmium telluride (CdTe) is an important semiconductor material, widely used in optoelectronic devices, infrared detectors, solar cells and other fields. Cadmium telluride is often used to manufacture X-ray and gamma-ray detectors, infrared detectors, etc. due to its good electrical properties. These detectors play an important role in medical imaging, security equipment, industrial non-destructive testing, nuclear physics experiments and other fields.

[0003] However, the resistivity of pure cadmium telluride crystals is low, and the application scenarios will be limited by the low resistivity. In order to increase the resistivity of cadmium telluride crystals and further improve their performance, such as photoelectric conversion efficiency or detection sensitivity, it is usually necessary to conduct doping experiments on cadmium telluride crystals. Doping can change the electrical properties of cadmium telluride, such as carrier concentration and mobility, to meet the needs of specific applications, but in the prior art, the doping method provided has problems such as uneven doping and poor stability, which limits its performance in practical applications. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a high-resistance cadmium telluride crystal doping method and its application to solve the problems raised in the above-mentioned background technology. The present invention has a simple operation process, is easy to realize industrial production, has uniform doping, good stability, and has broad market prospects.

[0005] In order to achieve the above object, the present invention is implemented by the following technical solution: a high-resistance cadmium telluride crystal doping method, comprising the following steps:

[0006] Step 1: Select high-purity cadmium telluride single crystal as raw material;

[0007] Step 2: Select one or more doping elements to prepare a doping source;

[0008] Step 3, placing the doping source in a vacuum melting furnace for heating treatment;

[0009] Step 4: growing a cadmium telluride single crystal from the melt;

[0010] Step 5: annealing the grown cadmium telluride single crystal to eliminate defects and stresses in the growth process;

[0011] Step 6: Test the resistivity, photoconductivity and other properties of the cadmium telluride single crystal after annealing.

[0012] Furthermore, in the step 2, the doping elements include arsenic (As), phosphorus (P), and boron (B), and the doping elements are mixed with the cadmium telluride single crystal.

[0013] Furthermore, the mixing ratio of the doping element to the cadmium telluride single crystal is (0.001-0.01)%: (99.999-99.99)%.

[0014] Furthermore, the purity of the high-purity cadmium telluride single crystal is above 99.99999%.

[0015] Furthermore, in step three, the heating is performed to a temperature above the melting point of the doping source until the doping element is fully dissolved in the cadmium telluride melt.

[0016] Furthermore, in step four, the vertical Bridgman method (VB) or other suitable crystal growth methods are used, and the specific process includes: in the early stage of crystal growth, the crystal growth furnace is kept fixed relative to the crystal growth container, and the temperature gradient zone is moved relative to the melt by controlling the change of the temperature field in the crystal growth furnace to grow the crystal.

[0017] Furthermore, in the later stage of crystal growth, the temperature field in the crystal growth furnace is kept constant, and the crystal is grown by controlling the movement of the crystal growth furnace relative to the crystal growth container.

[0018] Furthermore, the other suitable crystal growth methods include a melt method, a moving heater method, a vertical gradient freezing technique and an improved vertical Bridgman method, wherein the improved vertical Bridgman method introduces a seed crystal growth technique to grow a crystal ingot.

[0019] The invention discloses an application of a high-resistance cadmium telluride crystal doping method, which is applied to the preparation of semiconductor devices in the field of semiconductor materials. The high-resistance cadmium telluride crystal prepared by the doping method is used in the fields of optoelectronic devices and infrared detectors.

[0020] Beneficial effects of the present invention:

[0021] 1. The high-resistance cadmium telluride crystal doping method adopts the melt growth method, which has a simple operation process and is easy to realize industrial production. By controlling the proportion of the doping source and the smelting process, the doping elements are evenly distributed in the cadmium telluride crystal.

[0022] 2. The high-resistance cadmium telluride crystal obtained by the high-resistance cadmium telluride crystal doping method has good stability and is suitable for long-term use in optoelectronic devices, infrared detectors and other fields; it can be applied to a variety of semiconductor devices and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a flow chart of a high-resistance cadmium telluride crystal doping method. DETAILED DESCRIPTION

[0024] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0025] See also Figure 1 The present invention provides the following technical solution: a high-resistance cadmium telluride crystal doping method, which controls the proportion of doping sources and the smelting process to make the doping elements evenly distributed in the cadmium telluride crystal, and adopts a melt growth method, which has a simple operation process and is easy to realize industrial production. The specific preparation process is as follows:

[0026] 1. Select raw materials: Use high-purity cadmium telluride single crystal as raw material.

[0027] 2. Prepare a doping source: select one or more doping elements, such as arsenic (As), phosphorus (P), boron (B), etc., and mix them with a cadmium telluride single crystal in a certain proportion to prepare a doping source;

[0028] In this embodiment, arsenic (As) and cadmium telluride single crystals are mixed in a ratio of 1:100 to prepare a doping source.

[0029] 3. Melt growth: Place the doping source in a vacuum melting furnace, heat to 1000°C, and maintain for 2 hours to allow the arsenic to fully dissolve in the cadmium telluride melt.

[0030] 4. Crystal growth: A cadmium telluride single crystal is grown from a melt using the vertical Bridgman method. Specifically, in the early stage of crystal growth, the crystal growth furnace is kept fixed relative to the crystal growth container, and the temperature field in the crystal growth furnace is controlled to move the temperature gradient zone relative to the melt to grow the crystal; in the later stage of crystal growth, the temperature field in the crystal growth furnace is kept unchanged, and the crystal growth furnace is controlled to move relative to the crystal growth container to grow the crystal.

[0031] 5. Annealing: The grown cadmium telluride single crystal is annealed at a temperature of 500° C. for 24 hours to eliminate defects and stresses in the growth process.

[0032] 6. Performance test: The resistivity of the cadmium telluride single crystal after annealing was tested. The test results in this embodiment show that the resistivity is increased by one order of magnitude.

[0033] In this embodiment, the vertical Bridgman method in the above embodiment is replaced by a mobile heater method, a vertical gradient freezing technique and an improved vertical Bridgman method, wherein the mobile heater method specifically includes: the crucible is divided into three regions, which are a polycrystalline region, a Te-rich solution region and a single crystal region from top to bottom. During the growth process, as the crucible moves upward, polycrystalline cadmium telluride is fed at the dissolution interface, and single crystal cadmium telluride is continuously precipitated at the crystallization interface;

[0034] The vertical gradient freezing technology uses a one-dimensional gradient temperature field, and the melt is cooled from bottom to top in the crucible, so that the crystal grows in a directional manner.

[0035] The above doping method can be applied to a variety of semiconductor devices and has broad market prospects. The obtained high-resistance cadmium telluride crystal has good stability and is suitable for long-term use in optoelectronic devices, infrared detectors and other fields.

[0036] The basic principles and main features of the present invention and the advantages of the present invention are shown and described above. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention.

[0037] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A high-resistance cadmium telluride crystal doping method, characterized in that: The following steps are involved: Step 1: Select high-purity cadmium telluride single crystal as raw material; Step 2: Select one or more doping elements to prepare a doping source; Step 3, placing the doping source in a vacuum melting furnace for heating treatment; Step 4: growing a cadmium telluride single crystal from the melt; Step 5: annealing the grown cadmium telluride single crystal to eliminate defects and stresses in the growth process; Step 6: Test the resistivity, photoconductivity and other properties of the cadmium telluride single crystal after annealing.

2. The high-resistance cadmium telluride crystal doping method according to claim 1, characterized in that: In the step 2, the doping elements include arsenic (As), phosphorus (P), and boron (B), and the doping elements are mixed with the cadmium telluride single crystal.

3. The high-resistance cadmium telluride crystal doping method according to claim 2, characterized in that: The mixing ratio of the doping element to the cadmium telluride single crystal is (0.001-0.01)%: (99.999-99.99)%.

4. The high-resistance cadmium telluride crystal doping method according to claim 1, characterized in that: The purity of the high-purity cadmium telluride single crystal is above 99.99999%.

5. The high-resistance cadmium telluride crystal doping method according to claim 1, characterized in that: The step three is heating to a temperature above the melting point of the doping source until the doping element is fully dissolved in the cadmium telluride melt.

6. The high-resistance cadmium telluride crystal doping method according to claim 1, characterized in that: In the step 4, the vertical Bridgman method (VB) or other suitable crystal growth methods are used. The specific process includes: in the early stage of crystal growth, the crystal growth furnace is kept fixed relative to the crystal growth container, and the temperature gradient zone is moved relative to the melt by controlling the change of the temperature field in the crystal growth furnace to grow the crystal.

7. A high-resistance cadmium telluride crystal doping method according to claim 6, characterized in that: In the later stage of crystal growth, the temperature field in the crystal growth furnace is kept unchanged, and the crystal is grown by controlling the movement of the crystal growth furnace relative to the crystal growth container.

8. The high-resistance cadmium telluride crystal doping method according to claim 7, characterized in that: Other suitable crystal growth methods include a melt method, a moving heater method, a vertical gradient freezing technique, and an improved vertical Bridgman method, wherein the improved vertical Bridgman method introduces a seed crystal growth technique to grow a crystal ingot.

9. Application of a high-resistance cadmium telluride crystal doping method, characterized in that: It is used in the field of semiconductor materials to prepare semiconductor devices. The high-resistance cadmium telluride crystals prepared by this doping method are used in the fields of optoelectronic devices and infrared detectors.

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