CN105002561B - The method that ZnTe extension thick films are prepared on (100) GaAs substrates - Google Patents

Abstract

The invention discloses a method for preparing a ZnTe epitaxial thick film on a (100) GaAs substrate, which is used to solve the technical problem of slow growth rate of ZnTe epitaxial thick film prepared by the existing method. The technical solution is to put the treated ZnTe growth source and (100)GaAs substrate into the growth furnace chamber. Before the growth, the growth furnace chamber is repeatedly cleaned with high-purity Ar to remove residual air and filled with Ar to the target pressure, and the ZnTe is heated. After the growth source and (100) GaAs substrate are heated to a certain temperature, the growth source continues to heat up to the target temperature, and the substrate stops heating, relying on the thermal radiation at the growth source to maintain the temperature required for thick film growth. The invention controls the growth rate of the ZnTe epitaxial thick film by controlling the temperature of the ZnTe growth source, the pressure of the growth furnace chamber and the distance between the growth source and the substrate, and the growth rate is increased from 10 μm/h in the background technology to 20 μm/h ~100μm/h.

Description

Method of Preparing ZnTe Epitaxial Thick Film on (100) GaAs Substrate

technical field

The invention relates to a method for preparing a ZnTe epitaxial thick film, in particular to a method for preparing a ZnTe epitaxial thick film on a (100) GaAs substrate.

Background technique

ZnTe crystal is a II-VI compound semiconductor material, which is a direct band gap semiconductor with a band gap of 2.26eV at room temperature. It has a high second-order nonlinear coefficient and electro-optic coefficient, and the <110> oriented ZnTe bulk material has the best phase matching under the action of laser pulses around 800nm. It has become the most commonly used method for generating and detecting terahertz (THz) radiation. Electro-optic materials (Turchinovich D, Dijkhuis J I. Performance of combined<100>–<110>ZnTecrystals in an amplified THz time-domain spectrometer[J], Opticscommunications, 2007,270(1):96-99.). The development of theoretical research and practical application of ZnTe material devices has put forward more stringent requirements for the preparation of ZnTe crystal materials with high crystal quality, specific thickness and large size. The thick film refers to a thin film material with a film thickness of more than 10 μm. The ZnTe bulk material with a thickness ranging from 10 to 400 μm can be used to emit and detect broad-spectrum terahertz waves. The preparation process that meets the requirements is mainly ZnTe wafers that are ground, polished and cut from traditional ZnTe bulk materials. However, the growth equipment of the traditional ZnTe crystal growth method is expensive, and the damage layer produced by the grinding and polishing process greatly affects its optical properties. Related reports have proposed that ZnTe epitaxial films can be prepared by MOVPE, but the growth rate is low, and it is difficult to epitaxial ZnTe films with a thickness of more than 10 μm.

Document 1 "Yusuke Kμme, Qixin Guo, Yuji Fukuhara, Tooru Tanaka, Mitsuhiro Nishio, and Hiroshi Ogawa Growth and Characterization of ZnTe epilayers on (100)GaAs substrates by metallic organic vapor phase epitaxy Journal of Crystal Growth, 298, 445-448" published in 2007 A method for epitaxial ZnTe film on (100) GaAs substrate by MOVPE method. This method uses DMZn (dimethyl zinc) and DETe (diethyl zinc) as the source material, _H2 as the carrier gas, before the growth, the (100) GaAs substrate is chemically etched, and then preheated at 580 degrees 30min, film growth stage, DMZn and DETe transmission rate is controlled at 15μmol/min, the highest growth rate of the obtained film is 10μm/h, the crystal quality increases with the thickness of the epitaxial film, and the X-ray twin crystal rocking curve of the 12μm thick epitaxial film is half The peak width is 103arcsec. However, the growth rate of the MOVPE method is low, and it is difficult to achieve an epitaxial film with an epitaxial growth of more than 10 μm and a controllable thickness.

Document 2 "Chinese Invention Patent Application Publication No. CN104153001A" discloses a method for preparing a CdZnTe epitaxial film on a (100) GaAs single crystal substrate. The method adopts the near-space sublimation method (CSS) to chemically etch and preheat the (100) GaAs substrate. Then put the prepared CdZnTe growth source and (100) GaAs substrate into the growth chamber, adjust the distance between the source and the substrate, vacuumize, and fill Ar to the target pressure, turn on the heating system to heat up, and wait for deposition After the completion, the heating was stopped, and a high-quality CdZnTe film was epitaxially grown on the (100) GaAs single crystal substrate.

Contents of the invention

In order to overcome the disadvantage of slow growth rate of ZnTe epitaxial thick film prepared by the existing method, the invention provides a method for preparing ZnTe epitaxial thick film on (100) GaAs substrate. In this method, the treated ZnTe growth source and (100) GaAs substrate are placed in the growth furnace chamber, the ZnTe growth source is placed on an AlN ceramic sheet, and the (100) GaAs substrate is located directly above the ZnTe growth source, supported by a graphite block. The distance between the growth source and the substrate is regulated by adjusting the arrangement and specification of the graphite block. Before the growth, the growth furnace chamber is repeatedly cleaned with high-purity Ar to remove residual air and filled with Ar to the target pressure. The ZnTe growth source and (100) For GaAs substrates, after the growth source and the substrate reach a certain temperature, the growth source continues to heat up to the target temperature, the substrate stops heating, and the temperature required for thick film growth is maintained by relying on the thermal radiation at the growth source. By controlling different growth times, the growth ZnTe epitaxial thick films of different thicknesses. In order to grow a thicker ZnTe epitaxial thick film, the stacked growth method can be used, that is, the growth is divided into multiple times, and each growth is only used for a period of time when the temperature difference can be stable, and then the growth is stopped and the temperature is lowered until the growth furnace chamber drops to room temperature. , heated again to grow. The method of the invention prepares the ZnTe epitaxial thick film with fast growth rate and can epitaxially grow the ZnTe thick film of more than 10 μm.

The technical solution adopted by the present invention to solve the technical problems is: a method for preparing a ZnTe epitaxial thick film on a (100) GaAs substrate, which is characterized in that it comprises the following steps:

Step 1. After grinding, polishing and cleaning the ZnTe growth source, dry it with nitrogen, and then use a (100)GaAs substrate with a volume ratio of H ₂ SO ₄ :H ₂ O ₂ :H ₂ O of 3:1:1 Corrosion solution chemical corrosion 90 ~ 150s, ultrasonic cleaning, dry with nitrogen for later use.

Step 2: Put the (100) GaAs substrate and ZnTe growth source treated in step 1 into the growth furnace chamber, the ZnTe growth source is placed on the AlN ceramic sheet, the GaAs substrate is located directly above the growth source, and is supported by a graphite block. Adjust the graphite block to adjust the distance between the growth source and the substrate to be 1.5 mm to 5 mm, and seal the chamber of the growth furnace.

Step 3. Vacuum the chamber of the growth furnace to ≤1×10 -1 Pa, introduce high-purity Ar at 150 to 250 Pa, then evacuate to ≤1×10 ^-1 Pa, and ^perform the above operations 3 to 5 times to remove There is residual air in the growth furnace chamber, and the pressure of the growth furnace chamber is stabilized at ≤1×10 ^-1 Pa.

Step 4: preheating the (100)GaAs substrate, that is, heating the (100)GaAs substrate to 300-450° C., keeping it warm for 0.5h-1h, and reducing the temperature inside the growth furnace chamber to room temperature.

Step 5. Vacuum the chamber of the growth furnace to ≤1×10 ^-1 Pa, heat the ZnTe growth source and (100)GaAs substrate to 300-350°C, and keep it warm for 0.5h-1h. During the heat preservation period, put the growth furnace chamber The chamber is evacuated to ≤1×10 ^-1 Pa, and 150 to 250 Pa of high-purity Ar is introduced, and then evacuated to ≤1×10 ^-1 Pa, and the residual air in the chamber of the growth furnace is removed after 3 to 5 operations as above. Fill high-purity Ar to 80-200Pa. After the heat preservation is over, heat the ZnTe growth source to the required growth temperature of 700-850°C. (100)GaAs relies on the heat from the growth source to maintain growth at a temperature of 350-500°C. In the growth process, the temperature difference between the ZnTe growth source and the GaAs (100) substrate is kept at 250-350° C., and the growth time is 0.5h-6h.

Step 6. After the growth is over, feed high-purity Ar at 1000Pa to 10000Pa, drop the temperature to 500 to 650°C at 100 to 200°C/h according to the set slow cooling curve, and keep warm at this temperature for 0.5h to 3h; 100-300°C/h drops to 300-450°C, then cools down to room temperature with furnace cooling, and the growth of ZnTe thick film is completed.

Step five and step six are repeated multiple times to grow ZnTe thick films with different thicknesses.

The beneficial effects of the present invention are: the method puts the processed ZnTe growth source and (100) GaAs substrate into the chamber of the growth furnace, the ZnTe growth source is placed on the AlN ceramic sheet, and the (100) GaAs substrate is placed on the front of the ZnTe growth source. The upper part is supported by graphite blocks, and the distance between the growth source and the substrate is regulated by adjusting the placement and specifications of the graphite blocks. Before the growth, the chamber of the growth furnace is repeatedly cleaned with high-purity Ar to remove residual air and filled with Ar to the target pressure. ZnTe growth source and (100)GaAs substrate, after the growth source and substrate reach a certain temperature, the growth source continues to heat up to the target temperature, the substrate stops heating, and the temperature required for thick film growth is maintained by the thermal radiation at the growth source , by controlling different growth times to grow ZnTe epitaxial thick films with different thicknesses. In order to grow a thicker ZnTe epitaxial thick film, the stacked growth method can be used, that is, the growth is divided into multiple times, and each growth is only used for a period of time when the temperature difference can be stable, and then the growth is stopped and the temperature is lowered until the growth furnace chamber drops to room temperature. , heated again to grow. The method of the invention prepares the ZnTe epitaxial thick film with fast growth rate and can epitaxially grow the ZnTe thick film of more than 10 μm.

The method of the invention grows the ZnTe epitaxial thick film meeting the requirements of terahertz emission and detection devices through the optimization control of the growth process. (1) By controlling the temperature of the ZnTe growth source, the pressure of the growth furnace chamber, and the distance between the growth source and the substrate, the growth rate of the grown ZnTe epitaxial thick film can be controlled, and the growth rate ranges from 20 μm/h to 100 μm/h. Fast. (2) The present invention can grow a ZnTe epitaxial thick film with a designed thickness by controlling the growth time and adopting a stack growth process, and the thickness is 10 μm-400 μm. (3) In the present invention, by adjusting process parameters such as the cooling system, the distance between the growth source and the substrate, and the pressure in the growth furnace chamber, the crystal quality of the grown ZnTe epitaxial thick film meets the device requirements, and is measured by a high-resolution X-ray diffractometer ( 100) Theta/2θ and twin rocking curve scan spectra of ZnTe epitaxial film on GaAs substrate. There are only two diffraction peaks (200) and (400) in the θ/2θ XRD diffraction spectrum, indicating that the grown ZnTe film has only (100) orientation in the direction perpendicular to the substrate surface. The ZnTe epitaxial film with a thickness of 200 μm has a (400) plane X-ray twin crystal rocking curve with a half-maximum width of only 264 arcsec, indicating good crystal quality.

The present invention will be described in detail below in combination with specific embodiments.

detailed description

Embodiment 1: A 10 μm thick ZnTe epitaxial thick film is grown on a (100) GaAs substrate.

Step 1: Prepare the growth source: ZnTe crystal ingot grown by the vertical Bridgman method, cut the remaining polycrystalline block into 5×5×2mm ³ wafers after cutting off the single crystal, and place them on 5000# sandpaper Polish each surface of the wafer on the surface, use MgO suspension for rough polishing, and silica sol for fine polishing, then ultrasonically clean them in acetone and absolute ethanol for 15 minutes each, blow dry with high-purity N ₂ , and dry them in a vacuum oven. (100°C) for 10 minutes and set aside.

Prepare (100)GaAs substrate: (100)GaAs wafer is a GaAs crystal grown by vertical gradient solidification method, cut along the [100] crystal direction, polished on both sides, the surface treatment is Epi-ready level, and the thickness of the wafer is 500±25μm. Cut the wafer into a size of 10×10×0.5mm ³ with a diamond cutter, and ultrasonically clean the cut (100) GaAs substrate in acetone, absolute ethanol, and deionized water for 15 minutes, and then place it in H ₂ The volume ratio of SO ₄ :H ₂ O ₂ :H ₂ O is 3:1:1, chemically etched in the corrosion solution for 90s, ultrasonically cleaned with deionized water for 15min, dried with high-purity _N2 , and placed in a vacuum oven (100°C) Dry for 10 minutes and set aside.

Step 2: Ultrasonic clean the AlN ceramic sheet and graphite block with supporting heat conduction function in acetone and alcohol solution for 20 minutes, blow dry with high-purity N2, and dry in a vacuum oven (100°C) for 10 minutes for later use. Open the close-space sublimation furnace door, place the cleaned AlN ceramic sheet in the growth furnace chamber, place the prepared ZnTe growth source on the AlN ceramic sheet, and regularly place 4 graphite blocks around the growth source for support (100 ) GaAs substrate, adjust the distance between the growth source and the substrate to be 5 mm, and seal the chamber of the growth furnace.

Step 3: Vacuumize the chamber of the growth furnace to ≤1×10 ^-1 Pa, introduce 150Pa of high-purity Ar, then evacuate to ≤1×10 ^-1 Pa, and perform the above operation 3 to 5 times to remove the growth furnace The residual air in the chamber finally stabilizes the chamber pressure of the growth furnace at ≤1×10 ^-1 Pa.

Step 4: preheating the (100)GaAs substrate: heating the (100)GaAs substrate to 450° C., keeping it warm for 0.5 h, and lowering the temperature in the chamber of the growth furnace to room temperature.

Step 5: Vacuum the chamber of the growth furnace to ≤1×10 ^-1 Pa, heat the ZnTe growth source and (100)GaAs substrate to 350°C, and keep it warm for 1 hour. During the heat preservation period, evacuate the chamber of the growth furnace to ≤ 1×10 ^-1 Pa, after feeding 150Pa high-purity Ar, then evacuate to ≤1×10 ^-1 Pa, after 3 to 5 operations as above to remove residual air in the chamber of the growth furnace, then fill with high-purity Ar to 200Pa , after the heat preservation is over, heat the ZnTe growth source to the required growth temperature of 770°C, (100)GaAs substrate relies on the heat from the growth source to maintain the required growth temperature of 370°C, and the growth time is 0.5h.

Step 6: After the growth is over, pass through 5000Pa high-purity Ar, drop the temperature down to 500°C at 100°C/h according to the set slow cooling curve, and keep at this temperature for 0.5h; then drop to 300°C at 300°C/h , with the furnace cooling down to room temperature, take out the grown ZnTe thick film.

The test results of the spiral micrometer show that the thickness of the grown ZnTe thick film is 10 μm, and the growth rate of the thick film is 20 μm/h.

Embodiment 2: A 75 μm thick ZnTe epitaxial thick film is grown on a GaAs (100) substrate.

Step 1: Prepare the growth source: ZnTe crystal ingot grown by the vertical Bridgman method, cut the remaining polycrystalline block into 5×5×2mm ³ wafers after cutting off the single crystal, and place them on 5000# sandpaper Polish each surface of the wafer on the surface, use MgO suspension for rough polishing, and silica sol for fine polishing, then ultrasonically clean them in acetone and absolute ethanol for 15 minutes each, blow dry with high-purity N ₂ , and dry them in a vacuum oven. (100°C) for 10 minutes and set aside.

Prepare (100)GaAs substrate: (100)GaAs wafer is a GaAs crystal grown by vertical gradient solidification method, cut along the [100] crystal direction, polished on both sides, the surface treatment is Epi-ready level, and the thickness of the wafer is 500±25μm. Cut the wafer into a size of 10×10×0.5mm ³ with a diamond cutter, and ultrasonically clean the cut (100) GaAs substrate in acetone, absolute ethanol, and deionized water for 15 minutes, and then place it in H ₂ The volume ratio of SO ₄ :H ₂ O ₂ :H ₂ O is 3:1:1, chemically etched in the etching solution for 110s, ultrasonically cleaned with deionized water for 15min, dried with high-purity _N2 , and placed in a vacuum oven (100°C) Dry for 10 minutes and set aside.

Step 2: Ultrasonic clean the AlN ceramic sheet and graphite block with supporting heat conduction function in acetone and alcohol solution for 20 minutes, blow dry with high-purity N2, and dry in a vacuum oven (100°C) for 10 minutes for later use. Open the close-space sublimation furnace door, place the cleaned AlN ceramic sheet in the growth furnace chamber, place the prepared ZnTe growth source on the AlN ceramic sheet, and regularly place 4 graphite blocks around the growth source for support (100 ) GaAs substrate, adjust the distance between the growth source and the substrate to be 4 mm, and seal the chamber of the growth furnace.

Step 3: Vacuumize the chamber of the growth furnace to ≤1×10 ^-1 Pa, introduce 200Pa high-purity Ar, then evacuate to ≤1×10 ^-1 Pa, and perform the above operation 3 to 5 times to remove the growth furnace The residual air in the chamber finally stabilizes the chamber pressure of the growth furnace at ≤1×10 ^-1 Pa.

Step 4: Preheating the (100)GaAs substrate: heating the (100)GaAs substrate to 400° C., keeping it warm for 1 hour, and reducing the temperature in the chamber of the growth furnace to room temperature.

Step 5: Vacuum the chamber of the growth furnace to ≤1×10 ^-1 Pa, heat the ZnTe growth source and (100)GaAs substrate to 300°C, and keep it warm for 1 hour. During the heat preservation period, evacuate the chamber of the growth furnace to ≤ 1×10 ^-1 Pa, after feeding 200Pa high-purity Ar, then evacuate to ≤1×10 ^-1 Pa, after 3 to 5 operations as above to remove residual air in the chamber of the growth furnace, then fill with high-purity Ar to 160Pa , after the heat preservation is over, heat the ZnTe growth source to the required growth temperature of 800°C, (100)GaAs substrate relies on the heat of thermal radiation from the growth source to maintain the required growth temperature of 400°C, and the growth time is 1.5h.

Step 6: After the growth is over, pass through 3000Pa high-purity Ar, according to the set slow cooling curve, 150°C/h to 600°C, keep at this temperature for 1h; then 300°C/h to 300°C, with the furnace Cool down to room temperature, and take out the grown ZnTe thick film.

The test results of the spiral micrometer show that the thickness of the grown ZnTe thick film is 75 μm, and the growth rate of the thick film is 50 μm/h.

Embodiment 3: A 200 μm thick ZnTe epitaxial thick film is grown on a GaAs (100) substrate.

Step 1: Prepare the growth source: ZnTe crystal ingot grown by the vertical Bridgman method, cut the remaining polycrystalline block into 5×5×2mm ³ wafers after cutting off the single crystal, and place them on 5000# sandpaper Polish each surface of the wafer on the surface, use MgO suspension for rough polishing, and silica sol for fine polishing, then ultrasonically clean them in acetone and absolute ethanol for 15 minutes each, blow dry with high-purity N ₂ , and dry them in a vacuum oven. (100°C) for 10 minutes and set aside.

Prepare (100)GaAs substrate: (100)GaAs wafer is a GaAs crystal grown by vertical gradient solidification method, cut along the [100] crystal direction, polished on both sides, the surface treatment is Epi-ready level, and the thickness of the wafer is 500±25μm. Cut the wafer into a size of 10×10×0.5mm ³ with a diamond cutter, and ultrasonically clean the cut (100) GaAs substrate in acetone, absolute ethanol, and deionized water for 15 minutes, and then place it in H ₂ The volume ratio of SO ₄ :H ₂ O ₂ :H ₂ O is 3:1:1, chemically etched in the corrosion solution for 120s, ultrasonically cleaned with deionized water for 15min, dried with high-purity _N2 , and placed in a vacuum oven (100°C) Dry for 10 minutes and set aside.

Step 2: Ultrasonic clean the AlN ceramic sheet and graphite block with supporting heat conduction function in acetone and alcohol solution for 20 minutes, blow dry with high-purity N2, and dry in a vacuum oven (100°C) for 10 minutes for later use. Open the close-space sublimation furnace door, place the cleaned AlN ceramic sheet in the growth furnace chamber, place the prepared ZnTe growth source on the AlN ceramic sheet, and regularly place 4 graphite blocks around the growth source for support (100 ) GaAs substrate, adjust the distance between the growth source and the substrate to be 3 mm, and seal the chamber of the growth furnace.

Step 3: evacuate the chamber of the growth furnace to ≤1×10 ^-1 Pa, pass through 200Pa high-purity Ar, then evacuate to ≤1×10 ^-1 Pa, and perform the above operations 3 to 5 times to remove the growth The residual air in the furnace chamber finally stabilizes the pressure of the growth furnace chamber at ≤1×10 ^-1 Pa.

Step 4: preheating the (100)GaAs substrate: heating the (100)GaAs substrate to 400° C., keeping it warm for 0.5 h, and reducing the temperature in the chamber of the growth furnace to room temperature.

Step 5: Vacuum the chamber of the growth furnace to ≤1×10 ^-1 Pa, heat the ZnTe growth source and (100)GaAs substrate to 300°C, and keep it warm for 1 hour. During the heat preservation period, evacuate the chamber of the growth furnace to ≤ 1×10 ^-1 Pa, after feeding 200Pa high-purity Ar, then evacuate to ≤1×10 ^-1 Pa, after 3 to 5 operations as above to remove residual air in the chamber of the growth furnace, then fill with high-purity Ar to 160Pa , after the heat preservation is over, heat the ZnTe growth source to the required growth temperature of 850°C, (100)GaAs substrate relies on the heat from the growth source to maintain the required growth temperature of 450°C, and the growth time is 2h.

Step 6: After the growth is over, pass high-purity Ar at 3000Pa, and drop the temperature at 150°C/h to 600°C according to the set slow cooling curve, and keep it at this temperature for 2 hours; then drop it at 300°C/h to 300°C, Cool down to room temperature, and take out the grown ZnTe thick film.

The test results of the spiral micrometer show that the thickness of the grown ZnTe thick film is 200 μm, and the growth rate of the thick film is 100 μm/h.

Embodiment 4: A 400 μm thick ZnTe epitaxial thick film is grown on a GaAs (100) substrate.

Step 1: Prepare the growth source: ZnTe crystal ingot grown by the vertical Bridgman method, cut the remaining polycrystalline block into 5×5×2mm ³ wafers after cutting off the single crystal, and place them on 5000# sandpaper Polish each surface of the wafer on the surface, use MgO suspension for rough polishing, and silica sol for fine polishing, then ultrasonically clean them in acetone and absolute ethanol for 15 minutes each, blow dry with high-purity N ₂ , and dry them in a vacuum oven. (100°C) for 10 minutes and set aside.

Prepare (100)GaAs substrate: (100)GaAs wafer is a GaAs crystal grown by vertical gradient solidification method, cut along the [100] crystal direction, polished on both sides, the surface treatment is Epi-ready level, and the thickness of the wafer is 500±25μm. Cut the wafer into a size of 10×10×0.5 mm ³ with a diamond cutter, and ultrasonically clean the cut (100) GaAs substrate in acetone, absolute ethanol, and deionized water for 15 minutes, and then place it in H ₂ The volume ratio of SO ₄ :H ₂ O ₂ :H ₂ O is 3:1:1, chemically etched in the corrosion solution for 140s, ultrasonically cleaned with deionized water for 15min, dried with high-purity _N2 , and placed in a vacuum oven (100°C) Dry for 10 minutes and set aside.

Step 2: Ultrasonic clean the AlN ceramic sheet and graphite block with supporting heat conduction function in acetone and alcohol solution for 20 minutes, blow dry with high-purity N2, and dry in a vacuum oven (100°C) for 10 minutes for later use. Open the close-space sublimation furnace door, place the cleaned AlN ceramic sheet in the growth furnace chamber, place the prepared ZnTe growth source on the AlN ceramic sheet, and regularly place 4 graphite blocks around the growth source for support (100 ) GaAs substrate, adjust the distance between the growth source and the substrate to 2.5 mm, and seal the chamber of the growth furnace.

Step 3: Vacuumize the chamber of the growth furnace to ≤1×10 ^-1 Pa, introduce 200Pa high-purity Ar, then evacuate to ≤1×10 ^-1 Pa, and perform the above operation 3 to 5 times to remove the growth furnace The residual air in the chamber finally stabilizes the chamber pressure of the growth furnace at ≤1×10 ^-1 Pa.

Step 4: preheating the (100)GaAs substrate: heating the (100)GaAs substrate to 350° C., keeping it warm for 0.5 h, and lowering the temperature in the chamber of the growth furnace to room temperature.

Step 5: Vacuum the chamber of the growth furnace to ≤1×10 ^-1 Pa, heat the ZnTe growth source and (100)GaAs substrate to 300°C, and keep it warm for 0.5h. During the heat preservation period, evacuate the chamber of the growth furnace to ≤1×10 ^-1 Pa, after feeding 200Pa high-purity Ar, then evacuate to ≤1×10 ^-1 Pa, after 3 to 5 operations as above to remove residual air in the chamber of the growth furnace, and fill high-purity Ar to 100Pa, after the heat preservation is over, heat the ZnTe growth source to the required growth temperature of 820°C, (100)GaAs substrate relies on the heat of thermal radiation at the growth source to maintain the required growth temperature of 420°C, and the growth time is 5h.

Step 6: After the growth is over, pass high-purity Ar at 1000Pa, and drop the temperature at 150°C/h to 600°C according to the set slow cooling curve, and keep it at this temperature for 2 hours; Cool down to room temperature, and take out the grown ZnTe thick film.

The test results of the spiral micrometer show that the thickness of the grown ZnTe thick film is 400 μm, and the growth rate of the thick film is 80 μm/h.

Embodiment 5: A 400 μm thick ZnTe epitaxial thick film is grown on a GaAs (100) substrate by a stack growth method.

Step 1: Prepare the growth source: ZnTe crystal ingot grown by the vertical Bridgman method, cut the remaining polycrystalline block into 5×5×2mm ³ wafers after cutting off the single crystal, and place them on 5000# sandpaper Polish each surface of the wafer on the surface, use MgO suspension for rough polishing, and silica sol for fine polishing, then ultrasonically clean them in acetone and absolute ethanol for 15 minutes each, blow dry with high-purity N ₂ , and dry them in a vacuum oven. (100°C) for 10 minutes and set aside.

Prepare (100)GaAs substrate: (100)GaAs wafer is a GaAs crystal grown by vertical gradient solidification method, cut along the [100] crystal direction, polished on both sides, the surface treatment is Epi-ready level, and the thickness of the wafer is 500±25μm. Cut the wafer into a size of 10×10×0.5 mm ³ with a diamond cutter, and ultrasonically clean the cut (100) GaAs substrate in acetone, absolute ethanol, and deionized water for 15 minutes, and then place it in H ₂ The volume ratio of SO ₄ :H ₂ O ₂ :H ₂ O is 3:1:1, chemically etched in the corrosion solution for 150s, ultrasonically cleaned with deionized water for 15min, dried with high-purity _N2 , and placed in a vacuum oven (100°C) Dry for 10 minutes and set aside.

Step 2: Ultrasonic clean the AlN ceramic sheet and graphite block with supporting heat conduction function in acetone and alcohol solution for 20 minutes, blow dry with high-purity N2, and dry in a vacuum oven (100°C) for 10 minutes for later use. Open the close-space sublimation furnace door, place the cleaned AlN ceramic sheet in the growth furnace chamber, place the prepared ZnTe growth source on the AlN ceramic sheet, and regularly place 4 graphite blocks around the growth source for support (100 ) GaAs substrate, adjust the distance between the growth source and the substrate to be 1.5 mm, and seal the chamber of the growth furnace.

Step 3: Vacuumize the chamber of the growth furnace to ≤1×10 ^-1 Pa, introduce 250Pa high-purity Ar, then evacuate to ≤1×10 ^-1 Pa, and perform the above operation 3 to 5 times to remove the growth furnace The residual air in the chamber finally stabilizes the chamber pressure of the growth furnace at ≤1×10 ^-1 Pa.

Step 4: Preheating the (100)GaAs substrate: heating the (100)GaAs substrate to 300° C., keeping it warm for 0.5 h, and reducing the temperature in the chamber of the growth furnace to room temperature.

Step 5: Vacuum the chamber of the growth furnace to ≤1×10 ^-1 Pa, heat the ZnTe growth source and (100)GaAs substrate to 300°C, and keep it warm for 0.5h. During the heat preservation period, evacuate the chamber of the growth furnace to ≤1×10 ^-1 Pa, after feeding 250Pa high-purity Ar, then evacuate to ≤1×10 ^-1 Pa, after 3 to 5 operations as above to remove residual air in the chamber of the growth furnace, and fill high-purity Ar to 80Pa, after the heat preservation is over, heat the ZnTe growth source to the required growth temperature of 700°C, (100)GaAs substrate relies on the heat of thermal radiation from the growth source to maintain the required growth temperature of 500°C, and the growth time is 1h.

Step 6: After the growth is over, pass high-purity Ar at 10,000Pa, and drop the temperature at 200°C/h to 650°C according to the set slow cooling curve, and keep it at this temperature for 3 hours; then drop it at 100°C/h to 450°C, Cool down to room temperature.

For the stack growth of the ZnTe thick film, repeat steps 5 and 6 2 to 6 times, and take out the grown ZnTe thick film.

The test results of spiral micrometer show that the thickness of ZnTe thick film grown by lamination growth method is 400μm.

Claims (2)

1. A method for preparing ZnTe epitaxial thick film on (100) GaAs substrate, is characterized in that comprising the following steps: Step 1. After grinding, polishing and cleaning the ZnTe growth source, dry it with nitrogen, and then use a (100)GaAs substrate with a volume ratio of H ₂ SO ₄ :H ₂ O ₂ :H ₂ O of 3:1:1 Corrosion solution chemical corrosion 90 ~ 150s, after ultrasonic cleaning, dry with nitrogen for later use; Step 2: Put the (100) GaAs substrate and ZnTe growth source treated in step 1 into the growth furnace chamber, the ZnTe growth source is placed on the AlN ceramic sheet, the GaAs substrate is located directly above the growth source, and is supported by a graphite block. Adjust the graphite block to control the distance between the growth source and the substrate from 1.5mm to 5mm, and seal the chamber of the growth furnace; Step 3. Vacuum the chamber of the growth furnace to ≤1×10 -1 Pa, introduce high-purity Ar at 150 to 250 Pa, then evacuate to ≤1×10 ^-1 Pa, and ^perform the above operations 3 to 5 times to remove The residual air in the growth furnace chamber keeps the pressure in the growth furnace chamber at ≤1×10 ^-1 Pa; Step 4, preheating the (100)GaAs substrate, that is, heating the (100)GaAs substrate to 300-450°C, keeping it warm for 0.5h-1h, and reducing the temperature in the chamber of the growth furnace to room temperature; Step 5. Vacuum the chamber of the growth furnace to ≤1×10 ^-1 Pa, heat the ZnTe growth source and (100)GaAs substrate to 300-350°C, and keep it warm for 0.5h-1h. During the heat preservation period, put the growth furnace chamber The chamber is evacuated to ≤1×10 ^-1 Pa, and 150 to 250 Pa of high-purity Ar is introduced, and then evacuated to ≤1×10 ^-1 Pa, and the residual air in the chamber of the growth furnace is removed after 3 to 5 operations as above. Fill high-purity Ar to 80-200Pa. After the heat preservation is over, heat the ZnTe growth source to the required growth temperature of 700-850°C. (100)GaAs relies on the heat from the growth source to maintain growth at a temperature of 350-500°C. , during the growth process, the temperature difference between the ZnTe growth source and the GaAs(100) substrate is kept at 250-350°C, and the growth time is 0.5h-6h; Step 6. After the growth is over, feed high-purity Ar at 1000Pa to 10000Pa, drop the temperature to 500 to 650°C at 100 to 200°C/h according to the set slow cooling curve, and keep warm at this temperature for 0.5h to 3h; 100-300°C/h drops to 300-450°C, then cools down to room temperature with furnace cooling, and the growth of ZnTe thick film is completed. 2. The method for preparing a ZnTe epitaxial thick film on a (100) GaAs substrate according to claim 1, characterized in that: repeat step five and step six multiple times to grow ZnTe thick films of different thicknesses.