Ultra-thin ZnTe crystal for generation and detection of broadband terahertz and preparation method and application of ultra-thin ZnTe crystal

Abstract

The invention discloses an ultrathin ZnTe crystal for broadband terahertz generation and detection and a preparation method and application thereof, and relates to the technical field of crystal material processing. The method comprises the following steps: chamfering the edge of a ZnTe single crystal wafer, and thinning the ZnTe single crystal wafer in combination with mechanical grinding and polishing; aiming at the high surface quality requirement and the soft and brittle characteristics of the ZnTe crystal, a pressure-controlled double-sided polishing method is adopted during thinning, and the ultrathin ZnTe crystal and the crystal frame for terahertz application are processed. Compared with other traditional processing technologies, the method has the advantages that the ultrathin ZnTe wafer with the thickness of 50 microns or below can be processed, additional accompanying wafers are not needed, the problem that the ultrathin ZnTe crystal is fragile in the transportation and testing process is solved, and the requirements for broadband terahertz generation and detection at present are effectively met.

Description

Technical Field

[0001] The present invention relates to the technical field of crystal material processing, and in particular to an ultra-thin ZnTe crystal for broadband terahertz generation and detection, and a preparation method and application thereof. Background Art

[0002] Terahertz (THz) waves generally refer to electromagnetic waves with frequencies between 0.1THz and 10THz (wavelengths from 30μm to 3mm). Over the past 40 years, THz research has made significant progress, demonstrating its potential in both physical research and commercial applications. THz holds significant application value in medical imaging, industrial nondestructive testing, communications, and security inspection. However, the bandwidth of currently commercially available THz spectrometers, typically between 0.1THz and 3THz, is relatively narrow and cannot meet the broadband THz detection needs of industrial and scientific research. Therefore, research on broadband THz radiation sources and detectors holds significant application value.

[0003] ZnTe, with its zinc blende structure, is currently a highly sought-after electro-optical material for generating and detecting THz radiation due to its high second-order nonlinearity and electro-optic coefficient, excellent phase matching with femtosecond laser pulses near 800 nm, and relatively high damage threshold. However, THz spectrum generation and detection based on thicker ZnTe crystals (thickness > 0.5 mm) only have an effective bandwidth of 0.1 THz to 3 THz, which is insufficient to meet the requirements of broadband THz sources and detectors. By controlling the thickness of ZnTe crystals below 100 μm, it is hoped that an effective output bandwidth of 10 THz and above can be achieved. However, ZnTe crystals are soft materials with Vickers hardness ranging from 48.41 to 79.71 MPa and high fracture toughness. Therefore, it is very difficult to prepare ZnTe crystals below 100 μm and with dimensions greater than or equal to 5 mm × 5 mm.

[0004] Therefore, in order to realize the application of ZnTe crystals in the field of broadband terahertz generation and detection, it is urgent to develop ultra-thin ZnTe crystals with high surface quality. Summary of the Invention

[0005] In response to the shortcomings of the aforementioned background technology, the present invention primarily addresses the difficulty in processing existing ultrathin ZnTe crystals. The present invention provides an ultrathin ZnTe crystal for broadband terahertz generation and detection, as well as a preparation method and application thereof. This method chamfers the edges of the crystal, forming a "trapezoidal" shape during final thinning. This method effectively releases the internal stress of the ZnTe crystal, overcomes the crystal's brittleness, reduces cracking, and improves the preparation quality of the ultrathin ZnTe crystal.

[0006] The first object of the present invention is to provide a method for preparing an ultrathin ZnTe crystal for broadband terahertz generation and detection, comprising the following steps: The edge of the ZnTe crystal was chamfered with 1000-3000 mesh sandpaper until the edge cross section formed an isosceles triangle; One side of the ZnTe crystal is selected as the first side, and the chamfered crystal is coarse-ground using 1000-3000 mesh sandpaper to a crystal thickness of 300-700 μm, and then fine-ground using 5000-10000 mesh sandpaper to a crystal thickness of 200-500 μm; then the first side of the ZnTe crystal is subjected to coarse polishing and fine polishing in sequence, thereby completing the polishing of the first side of the ZnTe crystal; The first surface of the ZnTe crystal after polishing is glued to a grinding table with paraffin wax, and then the second surface of the ZnTe crystal is coarsely ground with 1000-3000 mesh sandpaper to a crystal thickness of 100-150 μm, and then finely ground with 5000-10000 mesh sandpaper to a crystal thickness of ≤100 μm, and then the second surface of the ZnTe crystal is subjected to coarse polishing and fine polishing in sequence, thus completing the polishing of the second surface of the ZnTe crystal; The rough polishing and fine polishing are performed sequentially, including: rough polishing for 3 to 10 minutes using a rough polishing liquid, and then fine polishing for multiple times using a fine polishing liquid, each fine polishing lasting 20 to 30 seconds, and then washing with deionized water for 3 to 10 seconds, and the fine polishing time lasts for a total of 3 to 5 minutes.

[0007] Preferably, after polishing the second surface of the ZnTe crystal, the method further comprises: Heat the paraffin until it melts, remove the wafer, wash it with an organic solvent such as petroleum ether or ethanol, and finally place the wafer in a crystal rack.

[0008] Preferably, the rough polishing liquid is prepared by uniformly mixing deionized water and light magnesium oxide in a ratio of 500 (ml): 10-30 (g).

[0009] Preferably, during rough polishing, a mirror effect can be observed on the surface of the ZnTe crystal after sufficient rough polishing on the polishing disk.

[0010] Preferably, the fine polishing liquid is prepared by uniformly mixing 30% hydrogen peroxide solution and silica sol solution in a volume ratio of 0.5-2:1.

[0011] Preferably, when chamfering, each edge of the wafer is evenly scratched more than 10 times on 1000-3000 mesh sandpaper at an angle of 45 degrees, so that the edge cross-section of the crystal forms an isosceles triangle.

[0012] Preferably, when grinding with sandpaper, the sandpaper is completely soaked with water.

[0013] Preferably, when manual coarse grinding, fine grinding and rough polishing are adopted, each coarse grinding, fine grinding and rough polishing is performed at least 200 times, and the crystal cross section will form a "trapezoidal" shape.

[0014] The second object of the present invention is to provide an ultra-thin ZnTe crystal for broadband terahertz generation and detection, wherein the broadband terahertz generated and detected by the crystal can reach 10 THz.

[0015] The third object of the present invention is to provide an application of an ultra-thin ZnTe crystal for broadband terahertz generation and detection in the field of broadband terahertz generation and detection.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an ultrathin ZnTe crystal for broadband terahertz generation and detection, a preparation method thereof, and applications thereof. The present invention chamfers the edges of the crystal so that the edges form a "trapezoidal" shape during the final thinning. This method effectively releases the internal stress of the ZnTe crystal, overcomes the soft and brittle problem of the crystal, reduces the generation of cracks, and improves the preparation quality of the ultrathin ZnTe crystal.

[0017] The present invention uses a grinding table to perform thinning during grinding and polishing. When the thickness is relatively thin, the pressure during grinding and polishing can be controlled by controlling the counterweight, thereby reducing the probability of cracks. At the same time, it can ensure that the two sides of the crystal remain parallel even at extremely thin thicknesses, meeting the requirements for use as generation and detection crystals in THz systems.

[0018] The coarse polishing liquid and the fine polishing liquid used in the present invention during polishing have a ratio that can not only polish efficiently, produce a mirror effect and improve the surface quality of the crystal, but also reduce surface scratches and even cracks caused by hard particles formed by abrasive aggregation.

[0019] The ultrathin ZnTe crystal prepared by the present invention has great application prospects in the field of broadband terahertz. Experiments have shown that it can be simultaneously used for the generation and detection of broadband terahertz, and its bandwidth can reach 10THz. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The preparation process and cross-sectional diagram of ultrathin ZnTe; Figure 2 Schematic diagram of the grinding table; Figure 3 (a) 50 μm ultra-thin ZnTe crystal and (b) its microscopic cross-section; Figure 4 Ultra-thin ZnTe of 100 μm; Figure 5 70μm ultra-thin ZnTe with sapphire substrate; Figure 6It is a crystal frame diagram; Figure 7 Time-domain and frequency-domain plots of terahertz generation and detection for ultrathin ZnTe crystals; Figure 8 Ultra-thin ZnTe crystals prepared by other methods. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below with reference to specific embodiments and drawings, but the embodiments are not intended to limit the present invention.

[0022] The present invention aims to provide an ultrathin ZnTe crystal for broadband terahertz generation and detection, as well as its preparation method and application. This approach primarily addresses the processing challenges associated with existing ultrathin ZnTe crystals. The method effectively overcomes the processing difficulties associated with the soft and brittle nature of ZnTe crystals, enabling the preparation of ultrathin ZnTe crystals and broadband terahertz generation and detection.

[0023] In order to achieve the above objectives, the present invention provides a first aspect of a method for preparing an ultrathin ZnTe crystal for broadband terahertz generation and detection, comprising the following steps: The edge of the ZnTe crystal was chamfered with 1000-3000 mesh sandpaper until the edge cross section formed an isosceles triangle; One side of the ZnTe crystal is selected as the first side, and the chamfered crystal is coarse-ground using 1000-3000 grit sandpaper to a crystal thickness of 300-700 μm, and then fine-ground using 5000-10000 grit sandpaper to a crystal thickness of 200-500 μm. Subsequently, the first side of the ZnTe crystal is subjected to coarse polishing and fine polishing in sequence, completing the polishing of the first side of the ZnTe crystal. At this point, the optical quality of the first side is high, and the crystal cross-section forms a "trapezoidal" shape, which can effectively release the internal stress caused by subsequent thinning. The polished first side of the ZnTe crystal is glued to the grinding table with paraffin wax. Then, the second side of the ZnTe crystal is coarse-ground with 1000-3000 mesh sandpaper using a total weight of 10g-200g including the grinding table to a crystal thickness of 100-150μm. Then, 5000-10000 mesh sandpaper is used for fine grinding to a crystal thickness of ≤100μm. Subsequently, the second side of the ZnTe crystal is subjected to coarse polishing and fine polishing in sequence to complete the polishing of the second side of the ZnTe crystal. This step requires controlling the pressure during crystal thinning to reduce the generation of cracks. Finally, the optical quality of both sides of the crystal is high.

[0024] Among them, the second side thinning process uses a grinding block for thinning, on the one hand to control the pressure during grinding and polishing, on the other hand to ensure that the two sides of the crystal are parallel.

[0025] The rough polishing and fine polishing are performed sequentially, including: rough polishing for 3 to 10 minutes using a rough polishing liquid, and then fine polishing for multiple times using a fine polishing liquid, each fine polishing lasting 20 to 30 seconds, and then washing with deionized water for 3 to 10 seconds, and the fine polishing time lasts for a total of 3 to 5 minutes.

[0026] After the polishing of the second surface of the ZnTe crystal is completed, the method further includes: Heat the paraffin until it melts, remove the wafer, wash it with an organic solvent such as petroleum ether or ethanol, and finally place the wafer in a crystal rack.

[0027] The rough polishing liquid is prepared by uniformly mixing deionized water and light magnesium oxide in a ratio of 500 (ml): 10-30 (g).

[0028] During rough polishing, a mirror effect can be observed on the surface of the ZnTe crystal after sufficient rough polishing on the polishing disc.

[0029] The fine polishing liquid is prepared by uniformly mixing 30% hydrogen peroxide solution and silica sol solution in a volume ratio of 0.5-2:1.

[0030] When chamfering, scratch each edge of the wafer evenly at an angle of 45° on 1000-3000 grit sandpaper for more than 10 times to make the edge cross section of the crystal form an isosceles triangle.

[0031] When grinding with sandpaper, soak the sandpaper completely with water.

[0032] When manual coarse grinding, fine grinding and rough polishing are used, each coarse grinding, fine grinding and rough polishing is performed at least 200 times, and the crystal cross-section will form a "trapezoidal" shape.

[0033] For example, see Figures 1 and 2 As shown, a method for preparing ultrathin ZnTe for broadband terahertz generation and detection includes: Step 1: Use 1000-3000 grit sandpaper to chamfer the edges of the ZnTe crystal until the edge cross section forms an isosceles triangle; Step 2: Use 1000-3000 mesh sandpaper to coarsely grind the first side of the chamfered crystal. It can be thinned to 300-700 μm by manual grinding or mechanical grinding. Then use 5000-10000 mesh sandpaper to finely grind to 200-500 μm. Finally, the cross section of the crystal will form a "trapezoidal" shape. Step 3: Rough polishing the first side of the thinned ZnTe crystal. The rough polishing liquid is prepared by mixing deionized water and light magnesium oxide in a ratio of 500 (ml): 10-30 (g). The polishing time is 3-10 minutes. Step 4: Fine polishing is performed on the first side of the ZnTe wafer. The fine polishing liquid used for fine polishing is prepared by mixing 30% hydrogen peroxide solution and silica sol solution in a volume ratio of 0.5-2:1. The surface is washed with deionized water for 3-10 seconds every 20-30 seconds of polishing, and the total polishing time is 3-5 minutes. Step 5: Use paraffin wax to stick the polished first side to a grinding table with a weight of 10g to 200g. Use 1000-3000 mesh sandpaper to grind the second side of the crystal to thin the crystal to 100-120μm. Then use 5000-10000 mesh sandpaper to thin the crystal to less than 100μm. Step 6: Rough polishing and fine polishing are performed on the second side of the ZnTe wafer, and the process is the same as steps 3 and 4.

[0034] Step 7: Heat the paraffin until it melts, remove the wafer, and wash the wafer with an organic solvent such as petroleum ether or ethanol. Figure 6 As shown, place it into the crystal rack.

[0035] When chamfering, scratch each edge of the wafer evenly at a 45-degree angle on 1000-3000 grit sandpaper for more than 10 times to ensure that the cross-section of the crystal side edge is an isosceles triangle. After thinning the first side, the cross-sectional shape of the crystal is a trapezoid, and the trapezoid is maintained for thinning the second side.

[0036] When rough grinding or fine grinding, the sandpaper should be completely soaked with water to ensure that the friction between the chip and the sandpaper is small.

[0037] If manual grinding and polishing is used, each time of rough grinding, fine grinding and rough polishing will be performed at least 200 times, and the crystal cross-section will form a "trapezoidal" shape.

[0038] When fine polishing, the process is to polish one side on the polishing cloth every 20 to 30 seconds, clean the surface within the next 3 to 10 seconds, repeat the above steps, and keep the total time at 3 to 5 minutes to remove the oxide layer.

[0039] After polishing one side first and thinning it to less than 500μm, its cross-section forms a "trapezoidal" shape, and then it is bonded to the grinding table with paraffin wax, and a total weight of 10g~200g including the grinding table is used to continue thinning to 100μm and below with 1000~10000 grit sandpaper.

[0040] After polishing, the residual paraffin on the crystal surface is cleaned with an organic solvent and the crystal is placed in a crystal rack.

[0041] A second aspect of the present invention provides an ultra-thin ZnTe crystal for broadband terahertz generation and detection, wherein the broadband terahertz generated and detected by the crystal can reach 10 THz.

[0042] A third aspect of the present invention provides an application of an ultra-thin ZnTe crystal for broadband terahertz generation and detection in the field of broadband terahertz generation and detection.

[0043] It should be noted that the experimental methods used in the present invention are all conventional methods unless otherwise specified; the reagents and materials used are all commercially available unless otherwise specified.

[0044] Example 1 Step 1: First, chamfer a 1mm thick ZnTe wafer on 2000 grit sandpaper at a 45° angle. Scratch each edge 20 times in the same direction to ensure that the chamfers are uniform and intersect on both sides, so that the edge cross-section forms an isosceles triangle.

[0045] Step 2: Choose any side of the chamfered ZnTe crystal and use 2000-grit sandpaper soaked in water for rough grinding. Hold the crystal with your hand and draw an "8" shape on the sandpaper 400 times, with each complete "8" shape being counted as one time. At the same time, thin the crystal to 500 μm.

[0046] Step 3: Wash the coarse-ground side of the ZnTe crystal with deionized water and perform fine grinding. Use 5000-grit sandpaper and soak it completely with water. Hold the wafer with your hand and draw an "8" shape on the sandpaper 400 times. Each complete "8" shape is counted as one time. At the same time, thin the crystal to 400 μm.

[0047] Step 4: Wash the finely ground side of the ZnTe crystal with deionized water and perform a rough polishing. Prepare a rough polishing solution by mixing 500 ml of deionized water and 20 g of light magnesium oxide. Hold the crystal with your hand and draw an "8" shape on the polishing cloth for 10 minutes. A mirror-like finish should be observed.

[0048] Step 5: Wash the rough-polished side of the ZnTe crystal with deionized water and perform fine polishing. The fine polishing liquid is prepared by mixing hydrogen peroxide solution and silica sol solution in a ratio of 1:1. Press the wafer with your hand and draw an "8" on the polishing cloth for 20 seconds. Then wash it with deionized water for 10 seconds. Repeat this process for a total of 3 minutes.

[0049] Step 6: Attach the polished side of the ZnTe crystal to the lapping table with paraffin wax and place it in a matching metal sleeve. Roughly grind with 2000-grit sandpaper using a 50g weight, including the lapping table. Press the sleeve down and scratch an "8" shape 200 times, counting each complete "8" shape as one stroke. Simultaneously, thin the crystal to 150μm.

[0050] Step 7: Use 5000-grit sandpaper to finely grind the coarsely ground ZnTe crystal. Press the sleeve by hand and draw an "8" shape 200 times. Each time a complete "8" shape is drawn, the crystal is thinned to 50μm.

[0051] Step 8: Roughly polish the finely ground ZnTe crystal using the same polishing liquid as above. Press the sleeve with your hand and draw an "8" shape on the polishing cloth for 10 minutes. A mirror effect can be observed on the crystal surface.

[0052] Step 9: Fine-polish the ZnTe crystal after rough polishing. Use the same polishing liquid as above. Press the sleeve with your hand to draw an "8" shape on the polishing cloth for 20 seconds. Then wash it with deionized water for 10 seconds. Repeat this process for a total of 3 minutes.

[0053] Step 10: Place the grinding table on the heating table to heat it, melt the paraffin, and wash it with an organic solvent. Finally, an ultra-thin ZnTe crystal with a thickness of 50 μm can be obtained. Figure 3 As shown, (a) is a 50μm ultra-thin ZnTe crystal and (b) is its microscopic cross-section.

[0054] Example 2 Step 1: Same as Example 1.

[0055] Step 2: The chamfered ZnTe crystal was glued to a 100 g grinding table with paraffin wax and coarsely ground using a UNIPOL-810 precision grinding and polishing machine from Shenyang Kejing Automation Equipment Co., Ltd. Use 2000-grit sandpaper and keep the sandpaper soaked with deionized water. Remove all excess counterweights and set the speed to 40 r / min for 5 min to thin the crystal to 500 μm. The crystal surface was then cleaned with deionized water.

[0056] Step 3: Replace the 5000 grit sandpaper and keep it soaked with deionized water for fine grinding. Remove all excess weights and set the speed to 40 r / min for 5 min. Thin the crystal to 400 μm and wash the crystal surface with deionized water.

[0057] Step 4: Replace the sandpaper with a polishing disc, prepare the rough polishing liquid the same as in Example 1, set the rotation speed to 50 r / min, remove all excess counterweights, continue for 10 minutes, polish the crystal surface, and a mirror effect can be observed.

[0058] Step 5: Remove the grinding table and perform fine polishing. The fine polishing liquid is the same as that in Example 1. Press the grinding table with your hand to draw an "8" shape on the polishing disc for 20 seconds, and then wash with deionized water for 10 seconds. Repeat this process for a total of 3 minutes.

[0059] Step 6: Place the grinding table on the heating table, melt the paraffin wax, stick the polished side back to the grinding table, and cool.

[0060] Step 7: Use 2000-grit sandpaper to rough-grind the second side, remove all excess counterweights, set the speed to 40 r / min, continue for 3 minutes, thin the crystal to about 150 μm, and wash the crystal surface with deionized water.

[0061] Step 8: Use 5000-grit sandpaper to finely grind the second side, remove all excess counterweights, set the speed to 40 r / min, continue for 3 minutes, thin the crystal to 100 μm, and wash the crystal surface with deionized water.

[0062] Step 9: Replace the sandpaper with a polishing disc, prepare the rough polishing liquid the same as in Example 1, set the rotation speed to 40 r / min, remove all excess counterweights, continue for 10 minutes, polish the crystal surface, and a mirror effect can be observed.

[0063] Step 10: Remove the grinding table and perform fine polishing. The fine polishing liquid is the same as that in Example 1. Press the grinding table with your hand to draw an "8" shape on the polishing disc for 20 seconds, and wash with deionized water for 10 seconds. Repeat this process for a total of 3 minutes.

[0064] Step 11: Place the grinding table on the heating table, melt the paraffin, carefully remove the crystal and wash it with an organic solvent such as petroleum ether, and finally obtain a 100μm ultra-thin ZnTe crystal such as Figure 4 shown.

[0065] Example 3: Step 1: Same as Example 1.

[0066] Step 2: Same as Example 1.

[0067] Step 3: Same as Example 1.

[0068] Step 4: Same as Example 1.

[0069] Step 5: Same as Example 1.

[0070] Step 6: Use paraffin wax to attach one side of the polished ZnTe crystal to a sapphire substrate, then to a lapping table. Place the crystal in a matching metal sleeve. Roughly grind the crystal using 3000-grit sandpaper, using a 20g counterweight (including the lapping table). Press the sleeve down and draw a figure-8 pattern 400 times, counting each complete figure-8 pattern as one stroke. Simultaneously, thin the crystal to 100μm.

[0071] Step 7: Use 7000-grit sandpaper to fine-grind the coarsely ground ZnTe crystal. Press the sleeve by hand and draw an "8" shape 300 times. Each complete "8" shape is counted as one time. At the same time, thin the crystal to 80μm.

[0072] Step 8: Roughly polish the finely ground ZnTe crystal using the same polishing liquid as above. Press the sleeve with your hand and draw an "8" shape on the polishing cloth for 5 minutes. A mirror effect can be observed on the crystal surface.

[0073] Step 9: Same as Example 9.

[0074] Step 10: Place the grinding table on the heating table and heat it. After the paraffin wax is melted, carefully remove the crystal and sapphire substrate together. Finally, an ultra-thin ZnTe crystal with a thickness of 70 μm can be obtained. Figure 5 shown.

[0075] Comparative Example 1 Step 1: Use 3000-grit sandpaper and soak it in water to coarsely grind a 1mm thick ZnTe crystal. Hold the crystal by hand and scratch the sandpaper in an "8" shape 500 times, with each complete "8" shape being counted as one time. Thin the crystal to about 500μm. Step 2: Wash the coarse-ground side of the ZnTe crystal with deionized water and perform fine grinding. Use 7000-grit sandpaper and soak it completely with water. Hold the wafer with your hand and draw an "8" shape on the sandpaper 500 times. Each complete "8" shape is counted as one time. At the same time, thin the crystal to 400μm.

[0076] Step 3: Same as step 4 of Example 1; Step 4: Same as step 5 of Example 1; Step 5: Use paraffin wax to stick the polished side of the ZnTe crystal to the grinding table and place it in a matching metal sleeve. Use 3000-grit sandpaper to coarsely grind with a total weight of 100g including the grinding table. Press the sleeve by hand to draw an "8" shape 200 times, each time a complete "8" shape is drawn, and at the same time, thin the crystal to 100μm. After thinning, cracks were found on the edge of the crystal. The crystal was then removed and the crystal broke, as shown in the following figure. Figure 8 (a) shown.

[0077] Comparative Example 2 Step 1: Same as Example 1; Step 2: Same as Example 2; Step 3: Replace the 5000 grit sandpaper and keep it soaked with deionized water for fine grinding. Press the wafer with your hand and draw an "8" shape on the sandpaper 400 times. Each time you draw a complete "8" shape, the crystal is thinned to 200μm. However, the crystal breaks during the thinning process. Figure 8 (b)

[0078] Figure 7 Time domain and frequency domain diagrams of generating and detecting terahertz for ultrathin ZnTe crystals, such as Figure 7 As shown, using the 50 μm ZnTe of Example 1 as the terahertz generation crystal and the 100 μm ZnTe of Example 2 as the detection crystal, the terahertz bandwidth of generation and detection can reach 10 THz.

[0079] The above tests show that regardless of whether manual polishing or mechanical polishing is used, the processed ultra-thin ZnTe crystals are of good quality, and the terahertz spectrum width that can be generated and detected can reach 10THz. However, for ultra-thin ZnTe crystals that have not been thinned or chamfered, cracks or even breakages occur during processing due to the soft and brittle nature of the crystal itself, resulting in processing failure. In summary, the present invention can solve the problem of cracks or even breakages that are easily generated during thinning due to the soft and brittle nature of the crystal, and can be applied to broadband terahertz generation and detection. The present invention describes preferred embodiments and their effects. However, those skilled in the art, once informed of the basic inventive concept, may make additional changes and modifications to these embodiments. Therefore, it is intended that the appended claims be interpreted to include the preferred embodiments as well as all changes and modifications that fall within the scope of the invention.

[0080] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing ultrathin ZnTe crystals for broadband terahertz generation and detection, characterized in that: The following steps are involved: The edge of the ZnTe crystal was chamfered with 1000-3000 mesh sandpaper until the edge cross section formed an isosceles triangle; Select one side of the ZnTe crystal as the first side, use 1000-3000 mesh sandpaper to coarsely grind the chamfered crystal on the first side to a thickness of 300-700 μm, and then use 5000-10000 mesh sandpaper to finely grind the crystal to a thickness of 200-500 μm; Then, the first surface of the ZnTe crystal is subjected to rough polishing and fine polishing in sequence, thereby completing the polishing of the first surface of the ZnTe crystal; The first surface of the ZnTe crystal after polishing is glued to a grinding table with paraffin wax, and then the second surface of the ZnTe crystal is coarsely ground with 1000-3000 mesh sandpaper to a crystal thickness of 100-150 μm, and then finely ground with 5000-10000 mesh sandpaper to a crystal thickness of ≤100 μm, and then the second surface of the ZnTe crystal is subjected to coarse polishing and fine polishing in sequence, thus completing the polishing of the second surface of the ZnTe crystal; The rough polishing and fine polishing are performed sequentially, including: rough polishing for 3 to 10 minutes using a rough polishing liquid, and then fine polishing for multiple times using a fine polishing liquid, each fine polishing lasting 20 to 30 seconds, and then washing with deionized water for 3 to 10 seconds, and the fine polishing time lasts for a total of 3 to 5 minutes.

2. The method for preparing ultrathin ZnTe crystal for broadband terahertz generation and detection according to claim 1, characterized in that: After completing the polishing of the second side of the ZnTe crystal, it also includes: Heat the paraffin until it melts, remove the wafer, wash it with an organic solvent such as petroleum ether or ethanol, and finally place the wafer in a crystal rack.

3. The method for preparing ultrathin ZnTe crystal for broadband terahertz generation and detection according to claim 1, characterized in that: The rough polishing liquid is prepared by uniformly mixing deionized water and light magnesium oxide in a ratio of 500 (ml): 10-30 (g).

4. The method for preparing ultrathin ZnTe crystal for broadband terahertz generation and detection according to claim 3, characterized in that: During rough polishing, a mirror effect can be observed on the surface of the ZnTe crystal after sufficient rough polishing on the polishing disc.

5. The method for preparing ultrathin ZnTe crystal for broadband terahertz generation and detection according to claim 1, characterized in that: The fine polishing liquid is prepared by uniformly mixing 30% hydrogen peroxide solution and silica sol solution in a volume ratio of 0.5-2:

1.

6. The method for preparing ultrathin ZnTe crystal for broadband terahertz generation and detection according to claim 1, characterized in that: When chamfering, scratch each edge of the wafer evenly at an angle of 45° on 1000-3000 grit sandpaper for more than 10 times to make the edge cross section of the crystal form an isosceles triangle.

7. The method for preparing ultrathin ZnTe crystal for broadband terahertz generation and detection according to claim 1, characterized in that: When grinding with sandpaper, soak the sandpaper completely with water.

8. The method for preparing ultrathin ZnTe crystal for broadband terahertz generation and detection according to claim 1, characterized in that: When manual coarse grinding, fine grinding and rough polishing are used, each coarse grinding, fine grinding and rough polishing should be performed at least 200 times, and the crystal cross-section will form a "trapezoidal" shape.

9. An ultrathin ZnTe crystal for broadband terahertz generation and detection, prepared by the method according to any one of claims 1 to 8, characterized in that: The broadband terahertz generated and detected by this crystal can reach 10 THz.

10. Use of the ultrathin ZnTe crystal for broadband terahertz generation and detection according to claim 9 in the field of broadband terahertz generation and detection.

Images