High-proportion 13N germanium single crystal and preparation method thereof

Abstract

The invention relates to the technical field of single crystal preparation, and particularly discloses a high-proportion 13N germanium single crystal and a preparation method thereof. According to the preparation method of the high-proportion 13N germanium single crystal, provided by the invention, the prepared germanium single crystal is divided into an impurity crystal section and a purified crystal section by controlling the step of pulling the single crystal, impurities in the germanium single crystal are intensively distributed in the impurity crystal section, the impurity content of the purified crystal section is reduced, and then the purified crystal section is used for further pulling and gathering the impurities, so that the purity of the high-proportion 13N germanium single crystal is improved. And reducing the impurity content in the purified crystal section of the germanium single crystal to prepare the high-proportion 13N germanium single crystal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of single crystal preparation, and discloses a high-occupancy 13N germanium single crystal and a preparation method thereof. BACKGROUND

[0002] In recent years, high-purity germanium detectors based on high-purity germanium single crystals have been widely used in dark matter detection and neutrino new property research. Dark matter and neutrino new property detection using high-purity germanium detectors has entered a new stage with ton / year mass exposure as a benchmark, producing only a few events. In particular, the detection of neutrinoless double beta decay is essentially to find a rare peak on a continuous background spectrum. The high-purity germanium detector has excellent energy resolution, far exceeding that of noble gas scintillation detectors. However, the purity of germanium required for the manufacture of the detector is extremely high, and the germanium needs to be purified to 13N level.

[0003] The existing high-purity germanium single crystal preparation method mainly obtains reduced germanium ingots through reduction, and then obtains 12N or more high-purity germanium polycrystals through horizontal zone melting, and finally obtains 13N ultra-high-purity germanium single crystals through the Czochralski method. However, the preparation method in the prior art is prone to introduce impurities in the production process, affecting the purity and performance of the germanium single crystal, and it is difficult to efficiently and stably prepare high-occupancy 13N germanium single crystals. How to stably prepare high-occupancy 13N germanium single crystals has become a technical problem to be solved in the field. SUMMARY

[0004] Therefore, the present application provides a high-occupancy 13N germanium single crystal and a preparation method thereof. The preparation method of the high-occupancy 13N germanium single crystal provided by the present application controls the steps of pulling the single crystal to divide the prepared germanium single crystal into an impurity crystal segment and a purification crystal segment. The impurities in the germanium single crystal are concentrated in the impurity crystal segment, reducing the impurity content of the purification crystal segment. Then, the purification crystal segment is further pulled to concentrate the impurities and reduce the impurity content in the purification crystal segment of the germanium single crystal, thereby preparing the high-occupancy 13N germanium single crystal.

[0005] To solve the above technical problems, the present application adopts the following technical solutions:

[0006] The present application provides a preparation method of a high-occupancy 13N germanium single crystal in the first aspect, comprising the following steps:

[0007] S1, after melting high-purity zone melting polycrystals, seeding, necking, fine necking, shoulder opening, isodiametric growth and tailing are performed to obtain a first purification crystal segment;

[0008] S2, the first purification crystal segment is subjected to fine necking and shoulder opening, and then is tailed to completely consume the high-purity zone melting polycrystals, to obtain a first purification crystal segment connected with a first impurity crystal segment at the bottom;

[0009] S3, after removing the first-stage impurity crystal section connected with the bottom of the first-stage purification crystal section, melting, seeding, necking, fine necking, shoulder, equal-diameter growth and tailing are performed to obtain a second-stage purification crystal section;

[0010] S4, after fine necking and shoulder of the second-stage purification crystal section, tailing is performed until the first-stage purification crystal section is completely consumed to obtain a second-stage purification crystal section connected with the bottom of a second-stage impurity crystal section;

[0011] S5, the steps of S3 and S4 are repeated n times to obtain a final-stage purification crystal section connected with the bottom of a final-stage impurity crystal section;

[0012] S6, after removing the final-stage impurity crystal section connected with the bottom of the final-stage purification crystal section, melting, seeding, necking, fine necking, shoulder and equal-diameter growth are performed, and then tailing is performed until the final-stage purification crystal section is completely consumed to obtain a high-13N-content germanium single crystal.

[0013] The inventors of the present application found that in the pulling process, impurities in the single crystal migrate according to the difference in the segregation coefficient, impurities with a segregation coefficient less than 1 migrate to the tail of the single crystal, impurities with a segregation coefficient greater than 1 migrate to the head of the single crystal, after one pulling operation, the conductivity type of the head of the single crystal is P type, the net impurity concentration is in the order of 10 10 cm -3 , the conductivity type of the tail is N type, the net impurity concentration is in the order of 10 11 cm -3 -10 12 cm -3 , and the impurities in the single crystal reach a balanced state. The preparation method provided by the present application removes the tail part rich in N-type impurities before pulling to break the balance of segregation and promote the purification process. After multiple cycles of purification operation, a germanium single crystal with a high 13N content is obtained.

[0014] Preferably, in S5, the n is an integer in 0-2.

[0015] By limiting the number of repetitions of S2, the present application can ensure the degree of purification and prepare a germanium single crystal with a high 13N content, and can avoid too many repetitions, which does not significantly improve the purification effect, and easily introduces impurities through the environment during the repetition process, thereby reducing the purity of the germanium single crystal.

[0016] Preferably, in S1, the net impurity concentration of the high-purity zone-fusion polycrystal is ≤9×10 10 cm -3 .

[0017] By limiting the net impurity concentration of the high-purity zone-fusion polycrystal, the present application can effectively improve the purity of the 13N germanium single crystal prepared.

[0018] Preferably, in S1, the melting temperature is 900-950℃.

[0019] The present application can ensure that the polycrystalline material maintains good fluidity in the molten state and avoids incomplete volatilization of impurities or thermal decomposition of the material due to excessively high temperature by limiting the melting temperature.

[0020] Preferably, in S1, the mass of the first-stage purification crystal section is 75-85% of the mass of the high-purity zone-melted polycrystalline material.

[0021] The present application can effectively remove most of the impurities in the material and reduce material waste and improve production efficiency by limiting the mass of the first-stage purification crystal section.

[0022] Preferably, in S2, the diameter of the thin neck is 1-5mm and the length is 20-40mm.

[0023] The present application can effectively eliminate dislocations during crystal growth, improve the integrity and purity of the crystal, easily remove the first-stage impurity crystal section, and avoid the introduction of impurities in the environment due to the long time of opening the furnace caused by the complex removal operation by limiting the diameter and length of the thin neck.

[0024] Preferably, in S3, the mass of the second-stage purification crystal section is 75-85% of the mass of the first-stage purification crystal section in S1.

[0025] Preferably, in S4, the diameter of the thin neck is 1-5mm and the length is 20-40mm.

[0026] The present application provides a high-13N-content germanium single crystal prepared by the preparation method.

[0027] Preferably, the 13N content in the high-13N-content germanium single crystal is 45-65%.

[0028] In summary, the preparation method of the high-13N-content germanium single crystal provided by the present application divides the prepared germanium single crystal into an impurity crystal section and a purification crystal section by controlling the crystal pulling step, concentrates the impurities in the impurity crystal section, reduces the impurity content in the purification crystal section, further pulls the purification crystal section, aggregates the impurities, and reduces the impurity content in the purification crystal section of the germanium single crystal to prepare the high-13N-content germanium single crystal. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described below. Obviously, the described embodiments are only one of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0030] Embodiment 1

[0031] The embodiment provides a preparation method of high-occupancy 13N germanium single crystal, and comprises the following steps:

[0032] S1, 3kg of high-purity zone-fusion polycrystal with a net impurity concentration of 9*10 10 cm -3 -9*10-6cm-3 is loaded in a quartz crucible, the temperature is raised to 937 DEG C, the germanium material is completely melted, a seed crystal is introduced, the diameter is reduced to 4mm after the length of the introduced seed crystal reaches 5mm, thin necking is performed, the length of the thin necking is 50mm, shoulder growth is started by reducing the temperature, when the diameter reaches 45mm, the temperature is raised for diameter growth, when the diameter reaches 50mm, diameter growth is started, when the weight of the single crystal reaches 2kg, the temperature is raised for tailing, the weight of the single crystal is controlled to reach 2.4kg, and a first-purification crystal segment is obtained.

[0033] S2, the first-purification crystal segment is subjected to thin necking, the diameter of the single crystal is controlled to be 4mm, after the thin necking is performed for 30mm, shoulder growth is performed, and then tailing is performed until the high-purity zone-fusion polycrystal is completely consumed, a first-purification crystal segment connected with a first-impurity crystal segment at the bottom is obtained.

[0034] S3, when the single crystal is reduced to room temperature, the furnace cover is opened, the first-impurity crystal segment in the first-purification crystal segment connected with the first-impurity crystal segment at the bottom is removed, the first-purification crystal segment is melted, a seed crystal is introduced, the diameter is reduced to 4mm after the length of the introduced seed crystal reaches 5mm, thin necking is performed, the length of the thin necking is 50mm, shoulder growth is started by reducing the temperature, when the diameter reaches 45mm, the temperature is raised for diameter growth, when the diameter reaches 50mm, diameter growth is started, when the weight of the single crystal reaches 1.5kg, the temperature is raised for tailing, the weight of the single crystal is controlled to reach 1.9kg, and a second-purification crystal segment is obtained.

[0035] S4, the second-purification crystal segment is subjected to thin necking, the diameter of the single crystal is controlled to be 4mm, after the thin necking is performed for 30mm, shoulder growth is performed, and then tailing is performed until the first-purification crystal segment is completely consumed, a second-purification crystal segment connected with a second-impurity crystal segment at the bottom is obtained.

[0036] S5, after the second-impurity crystal segment connected with the second-purification crystal segment is removed, melting, seed crystal introduction, necking, thin necking, shoulder growth and diameter growth are performed, and then tailing is performed until the second-purification crystal segment is completely consumed, and high-occupancy 13N germanium single crystal is obtained.

[0037] Embodiment 2

[0038] The embodiment provides a preparation method of high-occupancy 13N germanium single crystal, and comprises the following steps:

[0039] S1, 3kg of high-purity zone-fusion polycrystal with a net impurity concentration of 9*10 10 cm -3S1, a high purity zone melting polycrystal is prepared, and the high purity zone melting polycrystal is heated to 937 ℃, the germanium material is completely melted, a seed crystal is introduced, after the length of the seed crystal reaches 5 mm, necking is performed to reduce the diameter to 4 mm, thin necking is performed, the length of the thin necking is 50 mm, shoulder growth is started by reducing the temperature, when the diameter reaches 45 mm, heating is started for diameter growth, when the diameter reaches 50 mm, isothermal growth is started, when the weight of the single crystal reaches 2 kg, heating is started for tailing, and the weight of the single crystal is controlled to reach 2.4 kg, to obtain a first purification crystal segment;

[0040] S2, the first purification crystal segment is subjected to thin necking, the diameter of the single crystal is controlled to be 4 mm, after the thin necking is performed for 30 mm, shoulder growth is performed, and then tailing is performed until the first purification crystal segment is completely consumed, to obtain a first purification crystal segment connected with a first impurity crystal segment at the bottom;

[0041] S3, after the single crystal is reduced to room temperature, the furnace cover is opened, the first impurity crystal segment in the first purification crystal segment connected with the first impurity crystal segment at the bottom is removed, the first purification crystal segment is melted, a seed crystal is introduced, after the length of the seed crystal reaches 5 mm, necking is performed to reduce the diameter to 4 mm, thin necking is performed, the length of the thin necking is 50 mm, shoulder growth is started by reducing the temperature, when the diameter reaches 45 mm, heating is started for diameter growth, when the diameter reaches 50 mm, isothermal growth is started, when the weight of the single crystal reaches 1.5 kg, heating is started for tailing, and the weight of the single crystal is controlled to reach 1.9 kg, to obtain a second purification crystal segment;

[0042] S4, the second purification crystal segment is subjected to thin necking, the diameter of the single crystal is controlled to be 4 mm, after the thin necking is performed for 30 mm, shoulder growth is performed, and then tailing is performed until the first purification crystal segment is completely consumed, to obtain a second purification crystal segment connected with a second impurity crystal segment at the bottom;

[0043] S5, the steps of S3 and S4 are repeated once, to obtain a final purification crystal segment connected with a final impurity crystal segment at the bottom;

[0044] S6, after the final impurity crystal segment connected with the final purification crystal segment is removed, melting, seed crystal introduction, necking, thin necking, shoulder growth and isothermal growth are performed, and then tailing is performed until the final purification crystal segment is completely consumed, to obtain a high-occupancy 13N germanium single crystal.

[0045] Example 3

[0046] The embodiment provides a preparation method of a high-occupancy 13N germanium single crystal, and the method comprises the following steps:

[0047] S1, a quartz crucible is filled with 3 kg of a high-purity germanium material with a net impurity concentration ≤9×10 10 cm -3S1, a high purity zone melting polycrystal is prepared, and the high purity zone melting polycrystal is heated to 937 ℃, the germanium material is completely melted, a seed crystal is introduced, the diameter is reduced to 4 mm after the length of the introduced seed crystal reaches 5 mm, a necking process is performed, the length of the necking process is 50 mm, a shoulder is released by starting to reduce the temperature, the diameter reaches 45 mm, the temperature is increased to keep the diameter constant, the diameter reaches 50 mm, the growth is kept constant, the weight of the single crystal reaches 2 kg, the temperature is increased to finish, the weight of the single crystal reaches 2.4 kg, and a first purification crystal segment is obtained;

[0048] S2, the first purification crystal segment is necked, the diameter of the single crystal is controlled to be 4 mm, the necking process is performed for 30 mm, a shoulder is released, and then the first purification crystal segment is finished to completely consume the first impurity crystal segment connected at the bottom, and a second purification crystal segment is obtained;

[0049] S3, after the single crystal is reduced to room temperature, the first impurity crystal segment connected at the bottom of the first purification crystal segment is removed, the first purification crystal segment is melted, a seed crystal is introduced, the length of the introduced seed crystal reaches 5 mm, the diameter is reduced to 4 mm after a necking process, a necking process is performed, the length of the necking process is 50 mm, a shoulder is released by starting to reduce the temperature, the diameter reaches 45 mm, the temperature is increased to keep the diameter constant, the diameter reaches 50 mm, the growth is kept constant, the weight of the single crystal reaches 1.5 kg, the temperature is increased to finish, the weight of the single crystal reaches 1.9 kg, and a second purification crystal segment is obtained;

[0050] S4, the second purification crystal segment is necked, the diameter of the single crystal is controlled to be 4 mm, the necking process is performed for 30 mm, a shoulder is released, and then the first purification crystal segment is finished to completely consume the first impurity crystal segment connected at the bottom, and a second purification crystal segment is obtained;

[0051] S5, the steps S3 and S4 are repeated twice, and a final purification crystal segment connected with a final impurity crystal segment at the bottom is obtained;

[0052] S6, after the final impurity crystal segment connected with the final purification crystal segment is removed, a melting process, a seed crystal introduction process, a necking process, a necking process, a shoulder releasing process and a constant diameter growth process are performed, and then a finishing process is performed to completely consume the final purification crystal segment, and a high proportion 13N germanium single crystal is obtained.

[0053] Comparative Example 1

[0054] The present comparative example provides a preparation method of a germanium single crystal, comprising the following steps:

[0055] S1, a quartz crucible is filled with 3 kg of a high purity germanium material with a net impurity concentration ≤9×10 10 cm -3S1, 3kg of high-purity zone-melted polycrystal with a net impurity concentration of ≤9×10

[0056] S2, the first-stage purified crystal segment was subjected to necking, with the single crystal diameter controlled at 4mm, after 30mm of necking, shoulder growth was performed, and then end growth was performed until the high-purity zone-melted polycrystal was completely consumed, to obtain a first-stage purified crystal segment connected at the bottom to a first-stage impurity crystal segment, after the single crystal was cooled to room temperature, the furnace cover was opened, and the first-stage impurity crystal segment in the first-stage purified crystal segment connected at the bottom to a first-stage impurity crystal segment was removed, to obtain a germanium single crystal.

[0057] Comparative Example 2

[0058] The present comparative example provides a method for preparing a germanium single crystal, comprising the following steps:

[0059] S1, 3kg of high-purity zone-melted polycrystal with a net impurity concentration of ≤9×10 10 cm -3 were placed in a quartz crucible, the temperature was raised to 937℃, the germanium material was completely melted, a seed crystal was introduced, after the seed crystal length reached 5mm, necking was performed, to reduce the diameter to 4mm, necking was performed, with a necking length of 50mm, shoulder growth was started by reducing the temperature, when the diameter reached 45mm, temperature increasing and constant-diameter growth were started, when the diameter reached 50mm, constant-diameter growth was started, when the weight of the single crystal reached 2kg, end growth was started by increasing the temperature, and the weight of the single crystal was controlled to reach 2.4kg, to obtain a first-stage purified crystal segment;

[0060] S2, the first-stage purified crystal segment was subjected to necking, with the single crystal diameter controlled at 4mm, after 30mm of necking, shoulder growth was performed, and then end growth was performed until the high-purity zone-melted polycrystal was completely consumed, to obtain a first-stage purified crystal segment connected at the bottom to a first-stage impurity crystal segment;

[0061] S3, after the single crystal was cooled to room temperature, the furnace cover was opened, the first-stage impurity crystal segment in the first-stage purified crystal segment connected at the bottom to a first-stage impurity crystal segment was removed, the first-stage purified crystal segment was melted, a seed crystal was introduced, after the seed crystal length reached 5mm, necking was performed, to reduce the diameter to 4mm, necking was performed, with a necking length of 50mm, shoulder growth was started by reducing the temperature, when the diameter reached 45mm, temperature increasing and constant-diameter growth were started, when the diameter reached 50mm, constant-diameter growth was started, when the weight of the single crystal reached 1.5kg, end growth was started by increasing the temperature, and the weight of the single crystal was controlled to reach 1.9kg, to obtain a second-stage purified crystal segment;

[0062] S4, the secondary purification segment is necked, the single crystal diameter is controlled to be 4 mm, after the necking of 30 mm, shoulder is put, then tailing is performed until the primary purification segment is completely consumed, a secondary purification segment connected with a secondary impurity segment at the bottom is obtained;

[0063] S5, the steps of S3 and S4 are repeated for 3 times, a final-stage purification segment connected with a final-stage impurity segment at the bottom is obtained;

[0064] S6, after the final-stage impurity segment connected with the final-stage purification segment is removed, melting, seeding, necking, necking, shoulder and equal-diameter growth are performed, then tailing is performed until the final-stage purification segment is completely consumed, a high-occupancy 13N germanium single crystal is obtained.

[0065] The high-occupancy 13N germanium single crystals in examples 1-3 and the germanium single crystals in comparative examples 1-2 are sampled, a Hall tester (HMS3000) is used to test the net impurity concentration, the net impurity concentration is less than or equal to 2*10 10 cm -3 , the part is the effective part, and the test results are shown in table 1.

[0066] Table 1: net impurity concentration test results

[0067]

[0068] The above are preferred embodiments of the present application, and do not limit the protection scope of the present application, therefore, equivalent changes made on the basis of the structure, shape and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method for preparing a high-occupation 13N germanium single crystal, characterized by, The method comprises the following steps: S1, after melting high-purity zone-melted polycrystal, seeding, necking, thin necking, shoulder releasing, equal-diameter growth and tailing are performed to obtain a first purification crystal segment; S2, thin necking and shoulder releasing are performed on the first purification crystal segment, and then tailing is performed until the high-purity zone-melted polycrystal is completely consumed to obtain a first purification crystal segment connected with a first impurity crystal segment at the bottom; S3, after removing the first impurity crystal segment from the first purification crystal segment connected with the first impurity crystal segment at the bottom, melting, seeding, necking, thin necking, shoulder releasing, equal-diameter growth and tailing are performed to obtain a second purification crystal segment; S4, thin necking and shoulder releasing are performed on the second purification crystal segment, and then tailing is performed until the first purification crystal segment is completely consumed to obtain a second purification crystal segment connected with a second impurity crystal segment at the bottom; S5, the steps of S3 and S4 are repeated n times to obtain a final purification crystal segment connected with a final impurity crystal segment at the bottom; S6, after removing the final impurity crystal segment connected with the final purification crystal segment, melting, seeding, necking, thin necking, shoulder releasing and equal-diameter growth are performed, and then tailing is performed until the final purification crystal segment is completely consumed to obtain a high-occupancy 13N germanium single crystal.

2. The method of claim 1, wherein the high 13N germanium single crystal is prepared by the following steps of: In S5, the n is an integer in 0-2. ​ 3. The method for preparing high-percentage 13N germanium single crystals according to claim 1, characterized in that, In S1, the high purity zone refined polycrystalline has a net impurity concentration of < 9 x 10 10 cm -3 .

4. The method for preparing high-percentage 13N germanium single crystals according to claim 1, characterized in that, In S1, the temperature of the melting is 900-950°C.

5. The method of claim 1, wherein the high occupancy 13N germanium single crystal is prepared by a method comprising: In S1, the mass of the first purification crystal segment is 75%-85% of the mass of the high-purity zone-melted polycrystal. ​ 6. The method for preparing high-percentage 13N germanium single crystals according to claim 1, characterized in that, In S2, the diameter of the thin necking is 1-5 mm, and the length is 20-40 mm.

7. The method for preparing high-percentage 13N germanium single crystals according to claim 1, characterized in that, In S3, the mass of the second purification crystal segment is 75%-85% of the mass of the first purification crystal segment in S1.

8. The method of claim 1, wherein the high occupancy 13N germanium single crystal is prepared by a method comprising: In S4, the diameter of the thin necking is 1-5 mm, and the length is 20-40 mm. ​ 9. A high fraction 13N germanium single crystal, characterized by, The high-occupancy 13N germanium single crystal is prepared by the method of any one of claims 1-8.

10. The high-occupancy 13N germanium single crystal of claim 9, wherein, The 13N occupancy in the high-occupancy 13N germanium single crystal is 45%-65%.

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