Large-diameter infrared silicon single crystal, annealing method and application thereof

Abstract

The present application relates to the technical field of infrared optical material preparation, and particularly discloses a large-diameter infrared silicon single crystal, an annealing method thereof and application. The present application provides an annealing method for the large-diameter infrared silicon single crystal by controlling the temperature, heating rate and cooling rate and other parameters in different annealing stages under a protective gas atmosphere. The annealing method can make the single crystal silicon rod uniformly heated, does not increase the oxygen donor concentration, and effectively reduces the internal stress and lattice defects of the single crystal silicon rod. The infrared silicon single crystal prepared by the present application has excellent optical transmittance and optical uniformity, the average infrared transmittance in the range of 2-6 μm is greater than or equal to 52.4%, and the optical uniformity is less than or equal to 7.5*10 ‑5 The large-diameter infrared silicon single crystal prepared by the present application can be applied to the preparation of large-aperture infrared remote sensing detection lenses or infrared optical windows and related fields.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of infrared optical material preparation, in particular to a large-diameter infrared silicon single crystal and an annealing method and application thereof. BACKGROUND

[0002] High-resolution infrared optical detection systems are widely used in space exploration, earth exploration, remote control and telemetry, industrial temperature measurement, fire rescue, intelligent driving, medical treatment, environmental protection and consumer electronics and many other fields. Infrared optical materials are not only the basis of the infrared technology industry, but also the core of high-resolution infrared optical detection systems. Silicon single crystal, as one of the main types of infrared optical materials, has good infrared transmission performance, high refractive index, easy processing into lenses, corrosion resistance, low dispersion, no deliquescence, high mechanical strength and good chemical stability, and is the preferred material for 2-6 μm short and medium wave infrared spectral detection systems. With the continuous development of science and technology, the infrared lens, as the core component of the infrared detection system, has higher requirements for the size and quality of the silicon single crystal. The diameter of the infrared silicon single crystal lens required by the space exploration system is usually more than 300 mm, and the optical performance required is also higher and higher. However, during the process of drawing large-diameter infrared silicon single crystal with a diameter of more than 300 mm, due to the limitation of process conditions, more serious internal stress, lattice defects, oxygen donor effect and other problems are often caused, which seriously affect the optical performance of the infrared silicon single crystal.

[0003] At present, the annealing method of silicon single crystal mainly improves its electrical performance, and does not specifically solve the problems of optical performance caused by the process of drawing large-diameter infrared silicon single crystal. In addition, for the annealing of large-size silicon single crystal, the highest annealing temperature is too high (such as more than 1000℃), which can cause uneven heating and easily cause new stress problems. There are few reports in the prior art that the annealing method of large-diameter infrared silicon single crystal can eliminate the oxygen donor effect while solving the problems of stress, internal defects and substandard optical performance. SUMMARY

[0004] In view of the above technical problems, the present application provides a simple, efficient and highly applicable annealing method for large-diameter infrared silicon single crystal, which can reduce the internal stress, lattice defects and oxygen donor effect of the large-diameter infrared silicon single crystal, and the obtained product has excellent optical performance such as transmittance and optical uniformity. The infrared silicon single crystal prepared by the present application can be applied to the preparation of large-aperture infrared remote sensing detection lenses or infrared optical windows and related fields.

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

[0006] In a first aspect, the present application provides an annealing method for large-diameter infrared silicon single crystal, which comprises the following steps:

[0007] In a protective gas atmosphere, a large-diameter single crystal silicon rod is heated to T1 at a first preset rate and kept for a first preset time, then cooled to T2 at a second preset rate, cooled to T3 at a third preset rate, and cooled to T4 at a fourth preset rate, and cooled to obtain a large-diameter infrared silicon single crystal.

[0008] The T1 is 660 DEG C ~ 700 DEG C.

[0009] The T2 is 500 DEG C ~ 520 DEG C.

[0010] The T3 is 390 DEG C ~ 410 DEG C.

[0011] The T4 is 160 DEG C ~ 200 DEG C.

[0012] The first preset rate is 6 DEG C / min ~ 12 DEG C / min.

[0013] The second preset rate is 3 DEG C / min ~ 6 DEG C / min.

[0014] The third preset rate is 8 DEG C / min ~ 10 DEG C / min.

[0015] The fourth preset rate is 1 DEG C / min ~ 2 DEG C / min.

[0016] The temperature and time relationship curve of the annealing method of the large-diameter infrared silicon single crystal provided by the application is as shown in the figure. Figure 1 Under the protective gas atmosphere, by controlling the temperature, the heating rate and the cooling rate and other parameters in different annealing stages, the single crystal silicon rod can be heated uniformly, the oxygen donor concentration can not be increased, and the internal stress and the lattice defects of the single crystal silicon rod can be effectively eliminated. In the cooling to T2 stage (i.e. the first-stage cooling) and the cooling to T4 stage (i.e. the third-stage cooling), a lower cooling rate is adopted, which can effectively eliminate the internal stress and the lattice defects of the single crystal silicon rod; in the cooling to T3 stage (i.e. the second-stage cooling), a higher cooling rate is adopted, which can effectively eliminate the oxygen donor effect of the single crystal silicon rod. The annealing process of the large-diameter infrared silicon single crystal provided by the application can not only reduce the internal stress, the lattice defects and the oxygen donor effect of the large-diameter infrared silicon single crystal, but also effectively improve the optical transmittance and the optical uniformity of the infrared silicon single crystal, the average transmittance in the range of 2 μm ~ 6 μm is ≥ 52.4%, and the optical uniformity is ≤ 7.5 x 10 -5 In addition, the annealing method of the large-diameter infrared silicon single crystal provided by the application is simple and efficient, does not involve special process, has strong engineering application and wide application prospect.

[0017] Preferably, the large-diameter single crystal silicon rod comprises a single crystal silicon rod material with a diameter of 300mm-500mm; the purity of the protective gas is ≥99.999%; and the protective gas comprises argon or nitrogen.

[0018] In the present application, annealing under the protection of high-purity argon is taken as an example for illustration.

[0019] In the present application, the placing of the large-diameter single crystal silicon rod in a protective gas atmosphere specifically comprises placing the large-diameter single crystal silicon rod in a high-temperature-control-precision annealing furnace, vacuumizing the annealing furnace to 1-5Pa, and filling the annealing furnace with high-purity protective gas.

[0020] Preferably, the first preset time is 120min-240min.

[0021] Preferably, the first preset rate is 9℃ / min-10℃ / min.

[0022] Preferably, the second preset rate is 3℃ / min-5℃ / min.

[0023] Preferably, the third preset rate is 9℃ / min-10℃ / min.

[0024] Preferably, when the temperature drops to T2, the air cooling device is turned on, the temperature is lowered to T3 at the third preset rate, and the air cooling device is turned off; wherein the air speed of the air cooling device is 8m / s-15m / s.

[0025] Preferably, the fourth preset rate is 1.5℃ / min-2℃ / min.

[0026] In the second aspect, the present application provides a large-diameter infrared silicon single crystal prepared by the annealing method of the large-diameter infrared silicon single crystal provided in the first aspect.

[0027] The infrared silicon single crystal provided in the present application has excellent optical transmittance and optical uniformity, with an average transmittance ≥52.4% and an optical uniformity ≤7.5×10-5 in the range of 2μm-6μm, meeting the requirements of high-quality infrared optical systems. -5

[0028] In the third aspect, the large-diameter infrared silicon single crystal provided in the present application has excellent optical performance, and can be applied to the preparation of large-aperture infrared remote sensing lenses and infrared optical windows. BRIEF DESCRIPTION OF DRAWINGS

[0029] ​In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings described in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0030] Figure 1 The temperature and time relationship curve of the annealing method of the large-diameter infrared silicon single crystal provided by the present application;

[0031] Figure 2 The optical uniformity detection diagram of the infrared silicon single crystal I in the embodiment 1 of the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present application more clear, the following will further describe the present application in combination with specific embodiments. It should be understood that the specific embodiments described here are only used to explain the present application, and are not used to limit the present application.

[0033] According to the "GJB2919A-2015, People's Republic of China National Military Standard, Specification for Germanium for Infrared Optics", the average transmittance of the obtained infrared silicon single crystal in the 2-6um waveband is measured by using an infrared spectrometer; according to the specification, the optical uniformity of the obtained infrared silicon single crystal at 3.39um wavelength is measured by using an interferometer.

[0034] Embodiment 1

[0035] The present embodiment provides an annealing method of a large-diameter infrared silicon single crystal, which comprises the following steps:

[0036] S1, the diameter of the single crystal silicon rod after cutting head and tail is 450mm, the thickness is 100mm, and it is placed in a high temperature control precision annealing furnace, the annealing furnace is vacuumized to 5Pa, high purity argon with a purity of 99.9995% is filled to normal pressure, the temperature of the annealing furnace is raised to 670℃ at a heating rate of 8℃ / min, and the heating is turned off after constant temperature for 210min;

[0037] Start the cooling program, the first stage cooling is reduced to 510℃ at a cooling rate of 3.5℃ / min, the air blowing device is started and the wind speed reaches 13m / s, the second stage cooling is reduced to 410℃ at a cooling rate of 10℃ / min, and the air blowing device is turned off; the third stage cooling is reduced to 190℃ at a cooling rate of 1.5℃ / min;

[0038] S2, the above single crystal silicon rod is taken out from the annealing furnace, and it is naturally cooled to room temperature, that is, the large-diameter single crystal silicon after annealing is obtained, which is recorded as infrared silicon single crystal I.

[0039] The average infrared transmittance of the infrared silicon single crystal I in the range of 2-6 μm is 53.2%, and the optical uniformity at the wavelength of 3.39 μm is 4.2*10 -5 The optical uniformity detection diagram of the infrared silicon single crystal I is shown in Figure 2 .

[0040] Embodiment 2

[0041] The embodiment provides an annealing method of a large-diameter infrared silicon single crystal, and the annealing method comprises the following steps:

[0042] S1, a single crystal silicon rod with a diameter of 500 mm and a thickness of 20 mm after cutting the head and tail is placed in a high-temperature-control-precision annealing furnace, the annealing furnace is vacuumized to 4 Pa, high-purity argon with a purity of 99.9995% is filled to normal pressure, the temperature of the annealing furnace is raised to 700 DEG C at a temperature raising rate of 12 DEG C / min, and the heating is turned off after constant temperature for 240 min;

[0043] A cooling program is started, the first-stage cooling is reduced to 520 DEG C at a cooling rate of 3 DEG C / min, the air blowing device is started and the wind speed reaches 15 m / s, the second-stage cooling is reduced to 390 DEG C at a cooling rate of 10 DEG C / min, and the air blowing device is turned off; and the third-stage cooling is reduced to 160 DEG C at a cooling rate of 2 DEG C / min;

[0044] S2, the single crystal silicon rod is taken out from the annealing furnace, and is naturally cooled to room temperature, so that a large-diameter single crystal silicon after annealing is obtained, and is recorded as an infrared silicon single crystal II.

[0045] The average infrared transmittance of the infrared silicon single crystal II in the range of 2-6 μm is 52.4%, and the optical uniformity at the wavelength of 3.39 μm is 7.5*10 -5 .

[0046] Embodiment 3

[0047] The embodiment provides an annealing method of a large-diameter infrared silicon single crystal, and the annealing method comprises the following steps:

[0048] S1, a single crystal silicon rod with a diameter of 400 mm and a thickness of 200 mm after cutting the head and tail is placed in a high-temperature-control-precision annealing furnace, the annealing furnace is vacuumized to 2 Pa, high-purity argon with a purity of 99.9995% is filled to normal pressure, the temperature of the annealing furnace is raised to 680 DEG C at a temperature raising rate of 10 DEG C / min, and the heating is turned off after constant temperature for 180 min;

[0049] Start the cooling program, the first stage cooling to 510℃ at a cooling rate of 4℃ / min, open the blowing device to 10m / s, the second stage cooling to 400℃ at a cooling rate of 9℃ / min, close the blowing device; the third stage cooling to 180℃ at a cooling rate of 1.5℃ / min.

[0050] S2, take out the single crystal silicon rod from the annealing furnace, and cool it to room temperature naturally, to obtain the large-diameter single crystal silicon after annealing, which is recorded as infrared silicon single crystal III.

[0051] It is determined that the average infrared transmittance of the infrared silicon single crystal III in the range of 2μm~6μm is 53.1%, and the optical uniformity at the wavelength of 3.39μm is 2.6×10 -5 .

[0052] Example 4

[0053] The embodiment provides an annealing method of a large-diameter infrared silicon single crystal, which comprises the following steps:

[0054] S1, place the single crystal silicon rod with a diameter of 350mm and a thickness of 400mm after cutting the head into the high-temperature-control-precision annealing furnace, vacuumize the annealing furnace to 1Pa, fill high-purity argon with a purity of 99.9999% to normal pressure, and increase the temperature of the annealing furnace to 690℃ at a temperature increasing rate of 9℃ / min, and then close the heating after constant temperature for 150min;

[0055] Start the cooling program, the first stage cooling to 500℃ at a cooling rate of 4℃ / min, open the blowing device to 12m / s, the second stage cooling to 400℃ at a cooling rate of 9℃ / min, close the blowing device; the third stage cooling to 170℃ at a cooling rate of 1.5℃ / min.

[0056] S2, take out the single crystal silicon rod from the annealing furnace, and cool it to room temperature naturally, to obtain the large-diameter single crystal silicon after annealing, which is recorded as infrared silicon single crystal IV.

[0057] It is determined that the average infrared transmittance of the infrared silicon single crystal IV in the range of 2μm~6μm is 53.5%, and the optical uniformity at the wavelength of 3.39μm is 2.1×10 -5 .

[0058] Example 5

[0059] The embodiment provides an annealing method of a large-diameter infrared silicon single crystal, which comprises the following steps:

[0060] S1, the diameter of the cut head 300mm, thickness 500mm single crystal silicon rod is placed in high control precision annealing furnace, the annealing furnace is vacuumized to 3Pa, the purity of 99.999% high-purity argon is filled to normal pressure, the temperature of the annealing furnace is increased to 660 DEG C at a rate of 6 DEG C / min, and the heating is turned off after constant temperature 120 min;

[0061] Start the cooling program, the first stage cooling is reduced to 520 DEG C at a rate of 3 DEG C / min, the blowing device wind speed reaches 8m / s, the second stage cooling is reduced to 410 DEG C at a rate of 8 DEG C / min, and the blowing device is turned off; the third stage cooling is reduced to 200 DEG C at a rate of 1 DEG C / min;

[0062] S2, the above-mentioned single crystal silicon rod is taken out from the annealing furnace, and it is naturally cooled to room temperature, that is, the annealed large-diameter single crystal silicon is obtained, which is recorded as infrared silicon single crystal V.

[0063] It is determined that the average infrared transmittance of infrared silicon single crystal V in the range of 2μm~6μm is 52.5%, and the optical uniformity at 3.39μm is 6.5x10 -5 .

[0064] Comparative Example 1

[0065] This comparative example provides an annealing method of large-diameter infrared silicon single crystal, which is basically the same as that of Example 4, and the difference is that in step S1, "the temperature of the annealing furnace is increased to 690 DEG C at a rate of 9 DEG C / min" is changed to "the temperature of the annealing furnace is increased to 650 DEG C at a rate of 9 DEG C / min", and the rest of the parameters are the same as those of Example 4. The annealed large-diameter single crystal silicon is finally prepared, which is recorded as infrared silicon single crystal pair I.

[0066] It is determined that the average infrared transmittance of infrared silicon single crystal pair I in the range of 2μm~6μm is 51.4%, and the optical uniformity at 3.39μm is 1.5x10 -4 .

[0067] Compared with the infrared silicon single crystal IV prepared in Example 4, the optical performance of the infrared silicon single crystal pair I prepared in this comparative example is significantly reduced. The reason may be that T1 is reduced from 690 DEG C to 650 DEG C, and because the highest annealing temperature is reduced, the internal stress of the single crystal cannot be completely released, and it is also not conducive to repairing lattice defects, thereby affecting the plastic deformation ability of the single crystal, and further weakening the optical performance such as the average infrared transmittance in the range of 2μm~6μm and the optical uniformity at 3.39μm of the obtained product.

[0068] Comparative Example 2

[0069] The present comparative example provides an annealing method of a large-diameter infrared silicon single crystal, which is basically the same as that of Example 4, except that in step S1, “the temperature of the annealing furnace is increased to 690°C at a temperature increasing rate of 9°C / min” is changed to “the temperature of the annealing furnace is increased to 720°C at a temperature increasing rate of 9°C / min”, and the rest of the parameters are the same as those of Example 4. Finally, a large-diameter single crystal silicon after annealing is prepared, which is denoted as infrared silicon single crystal pair II.

[0070] It is determined that the average infrared transmittance of the infrared silicon single crystal pair II in the range of 2 μm to 6 μm is 51.2%, and the optical uniformity at 3.39 μm is 2.6 x 10 -4 .

[0071] Compared with the infrared silicon single crystal IV prepared in Example 4, the optical performance of the infrared silicon single crystal pair II prepared in the present comparative example is significantly reduced. The reason may be that the T1 is increased from 690°C to 720°C, and due to the increase of the highest annealing temperature, the oxygen donor concentration in the single crystal is increased, which leads to an increase in the carrier absorption of the single crystal, and further causes the optical performance of the obtained product, such as the average infrared transmittance in the range of 2 μm to 6 μm and the optical uniformity at 3.39 μm, to be significantly weakened.

[0072] Comparative Example 3

[0073] The present comparative example provides an annealing method of a large-diameter infrared silicon single crystal, which is basically the same as that of Example 4, except that in step S1, “the first stage of cooling is decreased to 500°C at a temperature decreasing rate of 4°C / min” is changed to “the first stage of cooling is decreased to 500°C at a temperature decreasing rate of 7°C / min”, and the rest of the parameters are the same as those of Example 4. Finally, a large-diameter single crystal silicon after annealing is prepared, which is denoted as infrared silicon single crystal pair III.

[0074] It is determined that the average infrared transmittance of the infrared silicon single crystal pair III in the range of 2 μm to 6 μm is 51.6%, and the optical uniformity at 3.39 μm is 1.6 x 10 -4 .

[0075] Compared with the infrared silicon single crystal IV prepared in Example 4, the optical performance of the infrared silicon single crystal pair III prepared in the present comparative example is significantly reduced. The reason may be that the temperature decreasing rate of the first stage of cooling is significantly increased, which causes the center temperature and the edge temperature of the large-size single crystal silicon to be non-uniform during the cooling process, and the lattice defect repair and stress release effect is not good, which leads to a significant weakening of the optical performance of the product.

[0076] Comparative Example 4

[0077] The present comparative example provides an annealing method of a large-diameter infrared silicon single crystal, which is basically the same as that of Example 4, except that in step S1, the phrase "the second-stage cooling is reduced to 400 DEG C at a cooling rate of 9 DEG C / min" is changed to "the second-stage cooling is reduced to 380 DEG C at a cooling rate of 11 DEG C / min", and the rest of the parameters are the same as those of Example 4. Finally, a large-diameter single crystal silicon after annealing is prepared, which is denoted as infrared silicon single crystal pair IV.

[0078] It is determined that the average infrared transmittance of the infrared silicon single crystal pair IV in the range of 2 μm to 6 μm is 51.8%, and the optical uniformity at 3.39 μm is 1.4 x 10 -4 .

[0079] Compared with the infrared silicon single crystal IV prepared in Example 4, the optical performance of the infrared silicon single crystal pair IV prepared in the present comparative example is significantly reduced. The reason may be that, within the scope of the present application, increasing the cooling rate of the second-stage cooling and slightly increasing T3 at the same time can make the central temperature and the edge temperature of the large-size single crystal silicon not uniform during the cooling process, and the long temperature interval of the rapid cooling can result in poor stress release effect, thereby significantly weakening the optical performance of the product in the range of 2 μm to 6 μm and at 3.39 μm wavelength.

[0080] Comparative Example 5

[0081] The present comparative example provides an annealing method of a large-diameter infrared silicon single crystal, which is basically the same as that of Example 4, except that in step S1, the phrase "the second-stage cooling is reduced to 400 DEG C at a cooling rate of 9 DEG C / min" is changed to "the second-stage cooling is reduced to 400 DEG C at a cooling rate of 5 DEG C / min", and the rest of the parameters are the same as those of Example 4. Finally, a large-diameter single crystal silicon after annealing is prepared, which is denoted as infrared silicon single crystal pair V.

[0082] It is determined that the average infrared transmittance of the infrared silicon single crystal pair V in the range of 2 μm to 6 μm is 50.8%, and the optical uniformity at 3.39 μm is 1.2 x 10 -4 .

[0083] Compared with the infrared silicon single crystal IV prepared in Example 4, the optical performance of the infrared silicon single crystal pair V prepared in the present comparative example is significantly reduced. The reason may be that, within the scope of the present application, decreasing the cooling rate of the second-stage cooling can make the intermittent oxygen in the large-size single crystal silicon form oxygen donors in this temperature interval, increase the single crystal carrier absorption, and thus significantly weaken the optical performance of the product.

[0084] In summary, the large-diameter infrared silicon single crystal obtained by the annealing method provided in Examples 1 to 5 can have an average infrared transmittance of more than 52%, and an optical uniformity of less than 1 x 10 -5, meet the use requirements of the infrared silicon single crystal in a large-aperture infrared optical system. Moreover, the annealing method of the large-diameter infrared silicon single crystal is simple and efficient, does not involve special processes, and has strong engineering applicability.

[0085] Compared with example 4, the optical properties such as the average infrared transmittance in the range of 2-6 mu m and the optical uniformity at 3.39 mu m of the product prepared in comparative examples 1-5 are significantly weakened, and the reason is that the T1, T2, T3 and T4 temperature settings and parameters such as the heating rate or the cooling rate at different stages are an organic whole. Within the parameter range provided by the present application, the single crystal silicon rod can be uniformly heated, the oxygen donor concentration can not be increased, and the internal stress and lattice defects of the single crystal silicon rod can also be effectively eliminated. The infrared silicon single crystal prepared by the present application has excellent optical transmittance and optical uniformity, the average infrared transmittance in the range of 2-6 mu m is greater than or equal to 52.4%, and the optical uniformity is less than or equal to 7.5*10 -5 . In view of the excellent optical properties of the large-diameter infrared silicon single crystal prepared by the present application, it can be used in the preparation of large-aperture infrared remote sensing lenses and infrared optical windows and related fields.

[0086] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement or improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for annealing a large-diameter infrared silicon single crystal, characterized in that: The annealing method comprises the following steps: Under a protective gas atmosphere, heating a large-diameter single crystal silicon rod at a first preset rate to T1 and holding the temperature for a first preset time, then cooling the rod at a second preset rate to T2, cooling the rod at a third preset rate to T3, and finally cooling the rod at a fourth preset rate to T4, and cooling the rod to obtain a large-diameter infrared silicon single crystal; Wherein, the T1 is 660°C~700°C; The temperature T2 is 500°C to 520°C; The T3 is 390°C to 410°C; The T4 is 160°C to 200°C; The first preset rate is 6°C / min to 12°C / min; The second preset rate is 3°C / min to 6°C / min; The third preset rate is 8°C / min to 10°C / min; The fourth preset rate is 1°C / min to 2°C / min.

2. The annealing method of large-diameter infrared silicon single crystal according to claim 1, characterized in that: The large-diameter single crystal silicon rod includes a single crystal silicon rod with a diameter of 300 mm to 500 mm; and / or The purity of the protective gas is ≥99.999%; and / or The protective gas includes argon or nitrogen.

3. The annealing method of large-diameter infrared silicon single crystal according to claim 1, characterized in that: The first preset time is 120 minutes to 240 minutes.

4. The annealing method of large-diameter infrared silicon single crystal according to claim 1, characterized in that: The first preset rate is 9°C / min to 10°C / min.

5. The annealing method of large-diameter infrared silicon single crystal according to claim 1, characterized in that: The second preset rate is 3°C / min to 5°C / min.

6. The annealing method of large-diameter infrared silicon single crystal according to claim 1, characterized in that: The third preset rate is 9°C / min to 10°C / min.

7. The annealing method of large-diameter infrared silicon single crystal according to claim 1, characterized in that: When the temperature drops to T2, the air cooling device is turned on, the temperature is lowered to T3 at a third preset rate, and the air cooling device is turned off; wherein the wind speed of the air cooling device is 8m / s~15m / s.

8. The annealing method of large-diameter infrared silicon single crystal according to claim 1, characterized in that: The fourth preset rate is 1.5°C / min to 2°C / min.

9. A large-diameter infrared silicon single crystal, characterized in that: The large-diameter infrared silicon single crystal is prepared by the annealing method according to any one of claims 1 to 8.

10. Use of the large-diameter infrared silicon single crystal according to claim 9 in a large-aperture infrared remote sensing detection lens or an infrared optical window.

Images