Preparation method of < 100 > crystal orientation high-purity germanium single crystal

Abstract

One lt; 100 gt; the preparation method of the crystal orientation high-purity germanium single crystal comprises the following steps: S1, crystal pulling: S11, loading a germanium ingot raw material into a crucible, 1t; 111gt, 111gt; the method comprises the following steps: S11, fixing a crystal orientation seed crystal on a seed crystal chuck, S12, blowing a pulling furnace, S13, melting a germanium ingot raw material to form a melt, S14, sequentially performing seeding, necking, necking, shouldering, diameter equalizing and diameter equalizing until a small amount of melt is left in a crucible, S15, re-melting the crystal to a seeding end of the seed crystal, S16, repeating the sub-steps S14 and S17, ending until the melt is completely pulled, S18, cooling, opening the pulling furnace, and cutting off the crystal; s2, performing a cutting test perpendicular to the axial direction of the crystal, and screening out a part of which the carrier concentration at two ends is less than 2E10cm <-3 > and the dislocation density meets 6000-10000 / cm < 2 > as a first qualified section; s3, as lt; 111gt, 111gt; the crystal orientation is used as the standard, 54.74 degrees are used as the steering included angle, and the 1t is cut from the first qualified section; 100 gt; a second qualified section of crystal orientation; and S4, rechecking the head and the tail of the second qualified section.

Description

Technical Field

[0001] The present disclosure relates to the field of single crystal growth, and more specifically to a method for preparing a high-purity germanium single crystal with a <100> crystal orientation. Background Art

[0002] High-purity germanium detectors play an increasingly important role in the high-tech field. They are widely used in experimental research in nuclear physics, particle physics, and astrophysics. They have the advantages of good energy resolution, high detection efficiency, and strong stability in detecting particles, especially X-rays and gamma rays. This detector-grade high-purity germanium single crystal material usually has the best detection efficiency in the <100> crystal direction, and its net impurity concentration must be less than 2E10cm -3 , the dislocation density must reach 500-10000 / cm 2 , and 6000-10000 / cm 2 A higher dislocation density range is the most ideal. In order to obtain germanium single crystal materials with such high requirements, a special single crystal pulling method is required.

[0003] There are generally two problems in growing the above-mentioned high-purity germanium materials with extremely high requirements using seed crystals with a crystal orientation of <100>. First, the single crystal rate is relatively low. It is difficult to achieve a single crystal rate of more than 99% for directly pulling high-purity germanium materials with a crystal orientation of <100>, and extremely high requirements are placed on the seed crystals and pulling equipment. Second, dislocations are difficult to control. Using the traditional Dash (necking) technology, since dislocations are easily eliminated, crystals with zero or low dislocations are often pulled out, making it difficult to screen out qualified materials.

[0004] The above two problems can be avoided by using seed crystals with a crystal orientation of <111> to pull high-purity germanium materials. The single crystal rate is high when the crystal grows downward, and the dislocations are relatively stable. It is difficult to completely remove the dislocations using the Dash technology, which is conducive to the proliferation of dislocations. However, high-purity germanium materials with a crystal orientation of <111> are not suitable for processing high-energy detectors.

[0005] Therefore, it is very important to explore a method for preparing high-purity germanium single crystals with a <100> crystal orientation. Summary of the invention

[0006] In view of the problems existing in the background technology, an object of the present invention is to provide a method for preparing a high-purity germanium single crystal with a <100> crystal orientation, which can obtain a carrier concentration of less than 2E10cm -3 At the same time, the dislocation density meets 6000-10000 / cm 2 High purity germanium single crystal with <100> crystal orientation.

[0007] Another object of the present disclosure is to provide a method for preparing a high-purity germanium single crystal with a <100> crystal orientation, which can improve the single crystal rate.

[0008] Another object of the present disclosure is to provide a method for preparing a high-purity germanium single crystal with a <100> crystal orientation, which can improve the overall qualified rate of the crystal.

[0009] Another object of the present disclosure is to provide a method for preparing a high-purity germanium single crystal with a <100> crystal orientation, which can obtain a crystal with a <100> crystal orientation that is more suitable for processing high-energy detectors.

[0010] Thus, a method for preparing a high-purity germanium single crystal with a <100> crystal orientation comprises the steps of: S1, crystal pulling, comprising the sub-steps of: S11, furnace loading: loading the corroded germanium ingot raw material into the crucible of the pulling furnace, fixing the corroded <111> crystal orientation seed crystal on the seed crystal chuck below the seed crystal rod, S12, cleaning: sealing the pulling furnace, evacuating the vacuum, and passing nitrogen gas for purging, and then passing hydrogen gas for purging, S13, material transformation: maintaining the hydrogen gas passing into the pulling furnace and maintaining the exhaust, starting the crystal rotation and the crucible rotation in opposite directions, controlling the power to increase the temperature so that the germanium ingot raw material is completely melted to form a melt, S14, crystal pulling: sequentially performing seeding, necking, thinning the neck, shouldering, and equalizing the diameter, to obtain a crystal whose diameter is maintained at the target size and equalized to a small amount of melt remaining in the crucible, S15, remelting: closing the crystal lifting, pulling The furnace is heated manually, and the crystal begins to melt back into the crucible. The seed crystal rod is lowered according to the melting situation, and the crystal melts back to the seed crystal seeding end. S16, secondary pulling of the crystal: repeat substeps S14 and S17, finishing: control the power to cool down, finish, until the melt in the crucible is completely pulled out, and the pulled crystal is obtained. S18, cooling: turn off the crystal lift and crucible lift, control the power to cool down to room temperature, then turn off the crystal rotation and crucible rotation, stop the hydrogen flow, switch to nitrogen filling and maintain exhaust, so that the pulling furnace reaches normal pressure, then stop nitrogen filling and exhaust, open the pulling furnace, cut the crystal, and complete the pulling; S2, sampling of equal-diameter sections: perform cutting tests perpendicular to the axial direction of the pulled crystal, and cut samples from the head and tail of the equal-diameter section to the middle, and screen out the crystals with carrier concentrations less than 2E10cm at both ends. -3 , while the dislocation density meets 6000-10000 / cm 2 The position is taken as the first qualified section of the crystal; S3, crystal steering: taking the <111> crystal direction as the reference and 54.74° as the steering angle, a second qualified section with a <100> crystal direction is cut from the first qualified section of the crystal, thereby steering the first qualified section with a <111> crystal direction into a second qualified section with a <100> crystal direction; S4, head-to-tail re-inspection of the second qualified section: sampling and testing the carrier concentration and dislocation density at the head and tail ends of the second qualified section, respectively, and obtaining that the carrier concentration at both ends is less than 2E10cm -3 , while the dislocation density meets 6000-10000 / cm 2 The product of high purity germanium single crystal with crystal orientation of <100>.

[0011] The beneficial effects of the present disclosure are as follows.

[0012] In the preparation method of the <100> crystal orientation high-purity germanium single crystal according to the present disclosure, a single-crystal rate of the crystal is improved, thereby improving the overall qualified rate of the crystal. At the same time, the dislocation density of the crystal is relatively stable, and more high-purity germanium crystals with carrier concentrations of less than 2E10cm at both ends can be screened out. -3 At the same time, the dislocation density meets 6000-10000 / cm 2 The crystals that are turned into <100> crystal orientation are more suitable for processing high-energy detectors.

[0013] In the preparation method of the <100> crystal orientation high-purity germanium single crystal according to the present disclosure, in step S1, through the one-time pulling of sub-step S14 and the remelting of sub-step S15, compared with the conventional situation without these two sub-steps, the contact area between the crystal raw material and hydrogen is increased, the amount of impurities in the crystal raw material carried away by hydrogen is increased, the crystal raw material is purified, and the crystal purity is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic diagram of crystal rotation.

[0015] Figure 2 This is the dislocation morphology of the <111> crystal direction at the head of the first qualified segment of Example 1.

[0016] Figure 3 This is the dislocation morphology of the <100> crystal direction at the head of the second qualified segment of Example 1. DETAILED DESCRIPTION

[0017] It will be understood that the disclosed embodiments are merely examples of the present disclosure, which may be implemented in various forms, and therefore, the specific details disclosed herein should not be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one of ordinary skill in the art to implement the present disclosure in various ways.

[0018] [Method for preparing high-purity germanium single crystal with <100> crystal orientation]

[0019] The method for preparing a high-purity germanium single crystal with a <100> crystal orientation according to the present disclosure comprises the following steps:

[0020] S1, crystal pulling, includes sub-steps:

[0021] S11, loading the furnace: load the corroded germanium ingot into the crucible of the pulling furnace, fix the corroded <111> crystal orientation seed crystal on the seed crystal chuck under the seed crystal rod,

[0022] S12, cleaning: evacuate the sealed pulling furnace and introduce nitrogen to purge, then introduce hydrogen to purge;

[0023] S13, melting materials: hydrogen is kept flowing into the pulling furnace and exhaust is maintained, the crystal turner and the crucible turner with opposite rotation directions are turned on, and the power is controlled to increase the temperature so that the germanium ingot raw material is completely melted to form a melt;

[0024] S14, pulling the crystal: performing seeding, necking, neck thinning, shouldering, and equalizing the diameter in sequence, until the crystal diameter is kept at the target size and the diameter is equalized to a small amount of melt remaining in the crucible;

[0025] S15, remelting: turn off the crystal lift, manually heat up the pulling furnace, and the crystal begins to melt back into the crucible. The seed crystal rod is lowered according to the melting situation, and the crystal melts back to the seed crystal seeding end;

[0026] S16, secondary crystal pulling: repeat sub-step S14;

[0027] S17, end: control the power to cool down and end until the melt in the crucible is completely pulled out to obtain a pulled crystal;

[0028] S18, cooling: turn off the crystal lift and crucible lift, control the power to cool down to room temperature, then turn off the crystal rotation and crucible rotation, stop passing hydrogen, switch to nitrogen filling and maintain exhaust, so that the pulling furnace reaches normal pressure, then stop filling nitrogen and exhaust, open the pulling furnace, cut the crystal, and complete the pulling;

[0029] S2, sampling of equal diameter sections: cutting test is done perpendicular to the axis of the pulled crystal, such as Figure 1 As shown in the figure, samples were cut from the head and tail of the equal diameter segment to the middle, and the carrier concentrations at both ends were screened out to be less than 2E10cm -3 At the same time, the dislocation density meets 6000-10000 / cm 2 The part is regarded as the first qualified section of the crystal;

[0030] S3, crystal steering: taking the <111> crystal orientation as a reference and taking 54.74° as a steering angle, a second qualified segment of the <100> crystal orientation is cut from the first qualified segment of the crystal, thereby steering the first qualified segment of the <111> crystal orientation into the second qualified segment of the <100> crystal orientation;

[0031] S4, re-inspection of the head and tail of the second qualified section: sample and test the carrier concentration and dislocation density at the head and tail of the second qualified section respectively, and the carrier concentration at both ends is less than 2E10cm -3 At the same time, the dislocation density meets 6000-10000 / cm 2 The product of high purity germanium single crystal with crystal orientation of <100>.

[0032] In the preparation method of the <100> crystal orientation high-purity germanium single crystal according to the present disclosure, a single-crystal rate of the crystal is improved, thereby improving the overall qualified rate of the crystal. At the same time, the dislocation density of the crystal is relatively stable, and more high-purity germanium crystals with carrier concentrations of less than 2E10cm at both ends can be screened out. -3 At the same time, the dislocation density meets 6000-10000 / cm 2 The crystals that are turned into <100> crystal orientation are more suitable for processing high-energy detectors.

[0033] In the preparation method of the <100> crystal orientation high-purity germanium single crystal according to the present disclosure, in step S1, through the one-time pulling of sub-step S14 and the remelting of sub-step S15, compared with the conventional situation without these two sub-steps, the contact area between the crystal raw material and hydrogen is increased, the amount of impurities in the crystal raw material carried away by hydrogen is increased, the crystal raw material is purified, and the crystal purity is improved.

[0034] In the charging of sub-step S11, in one example, the carrier concentration of the germanium ingot raw material is ≤ 8E10 cm -3 , carrier concentration of seed crystal in <111> crystal direction ≤8E10cm -3 ; Etching is performed using an etching solution prepared with a volume ratio of HNO3:HF=(2-3):1 until the surface is bright, then the surface is taken out, rinsed with pure water for more than 20 minutes, and blown dry with 9N high-purity nitrogen. In the charging of sub-step S11, in one example, the etched germanium ingot raw material is knocked into small pieces.

[0035] In the cleaning of sub-step S12, in one example, the vacuum is evacuated to below 1 Pa, purged with 9N nitrogen for 2 hours, and then purged with 9N hydrogen for more than 3 hours.

[0036] In the chemical material of sub-step S13, in one example, hydrogen is maintained to be introduced into the pulling furnace and exhaust is maintained to keep the pressure in the pulling furnace at normal pressure or slightly positive pressure. For example, the slightly positive pressure is a difference from normal pressure that does not exceed 5% of normal pressure. In the chemical material of sub-step S13, in one example, the hydrogen flow rate is 2-5L / min, the crystal rotation is 5-10r / min, the crucible rotation is 5-10r / min, the power is controlled to heat up to 1000±20℃ within 2-4h, keep the temperature constant, wait for the germanium ingot raw material to be completely melted, cool down to 940-970℃, and keep the temperature constant for 30-60min.

[0037] In the crystal pulling of sub-step S14, in one example, seeding is as follows: slowly insert the seed crystal into the melt, adjust the power according to the melt interface, wait for 10-20 minutes after a certain width aperture appears, and start seeding: gradually increase the pulling speed to 20-30mm / h, maintain this pulling speed for 10-30 minutes, and control the crystal diameter to be stable at 5-10mm as the standard; necking and thin necking are as follows: manually increase the pulling speed, evenly increase the pulling speed by 10-20mm / h at intervals of 10 minutes, until the pulling speed rises to 90-150mm / h, and control the crystal diameter to be stable at 3-5mm as the standard ; Keep the pulling speed at 90-150mm / h, pull the thin neck at this high pulling speed, and the pulling length at this stage is 90-150mm; shoulder release: evenly reduce the pulling speed to 20-30mm / h, and the frequency of reducing the pulling speed is to evenly reduce the pulling speed by 20-40mm / h at intervals of 10min, control the power to evenly cool down, and the cooling frequency is 120-180w / h. The crystal diameter gradually grows to the target diameter and stops cooling; equal diameter: observe the crystal diameter, manually control the power to keep the crystal diameter at the target diameter, and equalize the diameter until the melt in the crucible has 1 / 10-1 / 3 of the weight remaining.

[0038] In sub-step S15, in one example, the pulling furnace is manually heated to the temperature at which the crystal is seeded in sub-step S14, and the crystal is melted back to the seeding end of the seed crystal and then kept at a constant temperature for 30-60 minutes.

[0039] At the end of sub-step S17, in one example, the power is controlled to evenly cool down, the cooling frequency is 100-200w / h, and the end time is 2-3h, until the melt in the quartz crucible is completely pulled out.

[0040] In sub-step S18, in one example, the cooling frequency is 300-400w / h, and the purity of nitrogen is 9N.

[0041] In step S2, in one example, the single crystal rate of the crystal at the head of the equal diameter section at the shoulder position is above 99%.

[0042] In step S4, in one example, the weight of the second qualified segment is 24-30% relative to the total weight of the entire crystal.

[0043] [test]

[0044] Example 1

[0045] The method for preparing the high-purity germanium single crystal with a <100> crystal orientation of Example 1 comprises the following steps:

[0046] S1, crystal pulling adopts the following sub-steps:

[0047] S11, loading the furnace: load the corroded germanium ingot into the crucible of the pulling furnace, fix the corroded <111> crystal orientation seed crystal on the seed crystal chuck under the seed crystal rod,

[0048] in,

[0049] The raw material of germanium ingot is 8kg, and the carrier concentration of the ingot is 7E10cm -3 , the carrier concentration of the seed crystal in the <111> crystal orientation is 7E10cm -3 ;

[0050] The corrosion was carried out using a corrosion solution prepared with a volume ratio of HNO3:HF = 3:1. The surface was corroded until it was bright, then taken out, rinsed with pure water for 30 minutes, and dried with 9N high-purity nitrogen gas.

[0051] The corroded germanium ingot raw material is knocked into small pieces;

[0052] S12, cleaning: seal the pulling furnace, evacuate to 1 Pa, first purge with 9N nitrogen for 2 hours, then purge with 9N hydrogen for 5 hours;

[0053] S13, chemical material: maintain 9N hydrogen gas into the pulling furnace and maintain exhaust to keep the pressure in the pulling furnace at normal pressure, start the crystal rotation (i.e., seed crystal rotation) and crucible rotation (i.e., crucible rotation) with opposite rotation directions, control the power to increase the temperature so that the germanium ingot raw material is completely melted to form a melt, wherein the hydrogen flow rate is 4L / min, the crystal rotation is 8r / min, the crucible rotation is 8r / min, the power is controlled to increase the temperature to 1000°C within 4h, keep the temperature constant, wait for the germanium ingot raw material to be completely melted, cool down to 950°C, and keep the temperature constant for 45min;

[0054] S14, pulling the crystal: seeding, necking, neck thinning, shouldering, equalizing the diameter are performed in sequence, so that the crystal diameter is kept at the target size and the diameter is equalized to a small amount of melt remaining in the crucible,

[0055] in,

[0056] Seeding is as follows: slowly insert the seed crystal into the melt, adjust the power according to the melt interface, wait for 15 minutes after a certain width of aperture appears, and start seeding: gradually increase the pulling speed to 24mm / h, maintain this pulling speed for 10 minutes, and control the crystal diameter to be stable at 7mm as the standard;

[0057] Neck shrinkage and thin neck: manually increase the pulling speed, evenly increase the pulling speed by 15mm / h every 10min until the pulling speed reaches 100mm / h, and control the crystal diameter to be stable at 3.5mm as the standard; maintain the pulling speed at 100mm / h, and pull the thin neck at this high pulling speed. The pulling length at this stage is 100mm;

[0058] Shoulder release is: uniformly reduce the pulling speed to 24mm / h, the frequency of reducing the pulling speed is to uniformly reduce the pulling speed by 25mm / h every 10min, control the power to uniformly cool down, the cooling frequency is 160w / h, the crystal diameter gradually grows to the target diameter, and then stop cooling;

[0059] The equal diameter is: observe the crystal diameter, manually control the power, so that the crystal diameter is kept at the target diameter, and the equal diameter is reached until the melt in the crucible remains 1.8 kg (i.e., the melt in the crucible remains 22.5% by weight);

[0060] S15, remelting: turn off the crystal lift, manually heat the pulling furnace to the temperature of the seeding in sub-step S14, the crystal begins to melt back into the crucible, lower the seed crystal rod according to the melting situation, and keep the temperature constant for 50 minutes after the crystal melts back to the seeding end of the seed crystal;

[0061] S16, secondary crystal pulling: repeat sub-step S14;

[0062] S17, ending: Control the power to evenly cool down, the cooling frequency is 180w / h, and the ending time is 2.5h, until the melt in the crucible is completely pulled out, and the pulled crystal is obtained;

[0063] S18, cooling: turn off the crystal lift and crucible lift, control the power to cool down to room temperature, the cooling frequency is 380w / h, then turn off the crystal rotation and crucible rotation, stop the hydrogen flow, switch to nitrogen with a purity of 9N and maintain exhaust, so that the pulling furnace reaches normal pressure, then stop filling nitrogen and stop exhausting, open the pulling furnace, cut the crystal, and complete the pulling;

[0064] S2, sampling of equal diameter segments: Cutting test is performed perpendicular to the axis of the pulled crystal, and samples are cut from the head and tail of the equal diameter segment to the middle, and the carrier concentrations at both ends are less than 2E10cm -3 At the same time, the dislocation density meets 6000-10000 / cm 2 The part is regarded as the first qualified section of the crystal;

[0065] S3, crystal steering: taking the <111> crystal orientation as a reference and taking 54.74° as a steering angle, a second qualified segment of the <100> crystal orientation is cut from the first qualified segment of the crystal, thereby steering the first qualified segment of the <111> crystal orientation into the second qualified segment of the <100> crystal orientation;

[0066] S4, re-inspection of the head and tail of the second qualified section: sample and test the carrier concentration and dislocation density at the head and tail of the second qualified section respectively, and the carrier concentration at both ends is less than 2E10cm -3 At the same time, the dislocation density meets 6000-10000 / cm 2 The product of high purity germanium single crystal with crystal orientation of <100>.

[0067] Comparative Example 1

[0068] The same procedures as in Example 1 are as follows, except that in sub-step S11 of step S1, the <111> crystal orientation seed crystal is replaced by a <100> crystal orientation seed crystal, and step S3 and step S4 are not performed.

[0069] Comparative Example 2

[0070] Except that sub-step S15 and sub-step S16 in step S1 are not performed, the rest is the same as in Example 1. That is, the pulling in Comparative Example 2 is performed only once without a remelting process.

[0071] Figure 2 This is the dislocation morphology of the <111> crystal direction at the head of the first qualified segment of Example 1. Figure 3 This is the dislocation morphology of the <100> crystal direction at the head of the second qualified segment of Example 1.

[0072] Example 1 and Comparative Examples 1-2 were tested and the test results are shown in Table 1.

[0073] Table 1 Test results of Example 1 and Comparative Examples 1-2

[0074]

[0075] In Table 1, the single crystal rate of the shoulder position crystal is measured by using X-ray, the carrier concentration is detected by HL9900 of Toho Technology Company of the United States, and the dislocation density is detected according to the test method of dislocation density of germanium single crystal in GB / T5252-2020.

[0076] From the comparison between Example 1 and Comparative Example 1, it can be seen that in Example 1, by first pulling the high-purity germanium crystal with a <111> crystal orientation and then turning it into a crystal with a <100> crystal orientation, the single crystal rate of the crystal is improved, thereby improving the crystal quality; at the same time, the dislocation density of the crystal is relatively stable, and more crystals with carrier concentrations at both ends less than 2E10cm can be screened out. -3 At the same time, the dislocation density meets 6000-10000 / cm 2 Part of the body.

[0077] From the comparison between Example 1 and Comparative Example 2, it can be seen that in Example 1, during the process of primary pulling, remelting and secondary pulling, the contact area between the crystal raw material and 9N hydrogen is fully increased, thereby removing impurities in the crystal raw material and purifying the crystal raw material, thereby improving the crystal purity and the crystal qualification rate.

[0078] The above detailed description is used to describe multiple exemplary embodiments, but this document is not intended to be limited to the explicitly disclosed combinations. Therefore, unless otherwise stated, the various features disclosed herein can be combined together to form multiple additional combinations that are not shown for the sake of simplicity.

Claims

1. A <100> A method for preparing a high-purity germanium single crystal, characterized in that: Includes steps: S1, crystal pulling, includes sub-steps: S11, loading the furnace: Load the corroded germanium ingot raw materials into the crucible of the pulling furnace, <111> The crystal seed is fixed on the seed chuck under the seed rod. S12, cleaning: evacuate the sealed pulling furnace and introduce nitrogen to purge, then introduce hydrogen to purge; S13, melting materials: hydrogen is kept flowing into the pulling furnace and exhaust is maintained, the crystal turner and the crucible turner with opposite rotation directions are turned on, and the power is controlled to increase the temperature so that the germanium ingot raw material is completely melted to form a melt; S14, pulling the crystal: performing seeding, necking, neck thinning, shouldering, and equalizing the diameter in sequence, until the crystal diameter is kept at the target size and the diameter is equalized to a small amount of melt remaining in the crucible; S15, remelting: turn off the crystal lift, manually heat up the pulling furnace, and the crystal begins to melt back into the crucible. The seed crystal rod is lowered according to the melting condition, and the crystal is melted back to the seed crystal seeding end; S16, secondary crystal pulling: repeat sub-step S14; S17, end: control the power to cool down and end until the melt in the crucible is completely pulled out to obtain a pulled crystal; S18, cooling: turn off the crystal lift and crucible lift, control the power to cool down to room temperature, then turn off the crystal rotation and crucible rotation, stop passing hydrogen, switch to nitrogen filling and maintain exhaust, so that the pulling furnace reaches normal pressure, then stop filling nitrogen and exhaust, open the pulling furnace, cut the crystal, and complete the pulling; S2, sampling of equal diameter segments: Cutting test is performed perpendicular to the axis of the pulled crystal, and samples are cut from the head and tail of the equal diameter segment to the middle, and the carrier concentrations at both ends are less than 2E10cm -3 , while the dislocation density meets 6000-10000 / cm 2 The part is regarded as the first qualified section of the crystal; S3, crystal steering: <111> The crystal direction is taken as the reference, and the turning angle is 54.74°. <100> The second qualified section of the crystal direction, thus <111> The first qualified section of the crystal direction turns into <100> The second qualified section of the crystal direction; S4, re-inspection of the head and tail of the second qualified section: sample and test the carrier concentration and dislocation density at the head and tail of the second qualified section respectively, and the carrier concentration at both ends is less than 2E10cm -3 , while the dislocation density meets 6000-10000 / cm 2 of <100> Products of high purity germanium single crystal.

2. according to claim 1 <100> A method for preparing a high-purity germanium single crystal, characterized in that: In the charging of sub-step S11, The carrier concentration of germanium ingot raw material is ≤8E10cm -3 , <111> The carrier concentration of the seed crystal is ≤8E10cm -3 ; The corrosion was carried out using a corrosion solution prepared with a volume ratio of HNO3:HF=(2-3):1 until the surface was bright, then the sample was taken out, rinsed with pure water for more than 20 minutes, and dried with 9N high-purity nitrogen.

3. According to claim 1 <100> A method for preparing a high-purity germanium single crystal, characterized in that: In the cleaning of sub-step S12, the vacuum is evacuated to below 1 Pa, purged with 9N nitrogen for 2 hours, and then purged with 9N hydrogen for more than 3 hours.

4. according to claim 1 <100> A method for preparing a high-purity germanium single crystal, characterized in that: During the chemical reaction in sub-step S13, hydrogen is maintained to flow into the pulling furnace and exhaust is maintained to keep the pressure in the pulling furnace at normal pressure or slightly positive pressure.

5. According to claim 1 <100> A method for preparing a high-purity germanium single crystal, characterized in that: In the chemical material of sub-step S13, the hydrogen flow rate is 2-5L / min, the crystal rotation is 5-10r / min, the crucible rotation is 5-10r / min, and the power is controlled to heat up to 1000±20℃ within 2-4h, keep the temperature constant, wait for the germanium ingot raw material to be completely melted, cool down to 940-970℃, and keep the temperature constant for 30-60min.

6. According to claim 1 <100> A method for preparing a high-purity germanium single crystal, characterized in that: In the crystal pulling in sub-step S14, Seeding is as follows: slowly insert the seed crystal into the melt, adjust the power according to the melt interface, wait for 10-20 minutes after a certain width of aperture appears, and start seeding: gradually increase the pulling speed to 20-30mm / h, maintain this pulling speed for 10-30min, and control the crystal diameter to be stable at 5-10mm as the standard; Neck shrinkage and thin neck: manually increase the pulling speed, increase the pulling speed evenly by 10-20mm / h every 10min until the pulling speed reaches 90-150mm / h, and control the crystal diameter to be stable at 3-5mm as the standard; maintain the pulling speed at 90-150mm / h, and pull the thin neck at this high pulling speed. The pulling length at this stage is 90-150mm; Shoulder release is: evenly reduce the pulling speed to 20-30mm / h, the frequency of reducing the pulling speed is to evenly reduce the pulling speed by 20-40mm / h at intervals of 10min, control the power to evenly cool down, the cooling frequency is 120-180w / h, the crystal diameter gradually grows to the target diameter, and then stop cooling; The equal diameter means: observe the crystal diameter and manually control the power to keep the crystal diameter at the target diameter, and equalize the diameter until the melt in the crucible remains 1 / 10-1 / 3 of its weight.

7. According to claim 1 <100> A method for preparing a high-purity germanium single crystal, characterized in that: In sub-step S15, the pulling furnace is manually heated to the temperature at which the crystal is seeded in sub-step S14, and the crystal is melted back to the seeding end of the seed crystal and then kept at a constant temperature for 30-60 minutes.

8. According to claim 1 <100> A method for preparing a high-purity germanium single crystal, characterized in that: At the end of sub-step S17: control the power to evenly cool down, the cooling frequency is 100-200w / h, and the end time is 2-3h, until the melt in the quartz crucible is completely pulled out.

9. According to claim 1 <100> A method for preparing a high-purity germanium single crystal, characterized in that: In sub-step S18, the cooling frequency is 300-400w / h, and the purity of nitrogen is 9N.

10. According to claim 1 <100> A method for preparing a high-purity germanium single crystal, characterized in that: In step S2, the single crystal rate of the crystal at the head of the equal diameter section at the shoulder position is above 99%. In step S4, the weight of the second qualified segment is 24-30% relative to the total weight of the entire crystal.

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