Methods for purifying germanium by zone smelting

Abstract

A method for refining germanium by zone melting includes: S1, germanium material processing; S2, furnace loading; S3, moving the heating coil from the head to the tail; S4, zone melting, including: S41, when the germanium material at the tail is completely solidified, moving in the reverse direction, first quickly moving to point B, melting the material from point B, and moving from point B to the head; S42, when the germanium material at the head is completely solidified, moving in the forward direction, first quickly moving to point A, melting the material from point A, and moving from point A to the tail; S43, repeating S41 and S42; 5. Zone Melting II, including: S51, when the germanium material at the tail end is completely solidified, move in the reverse direction, first quickly move to point B1, which is farther from the tail end than point B, melt the material from point B1, and move from point B1 to the head; S52, when the germanium material at the head end is completely solidified, move the heating coil in the forward direction, first quickly move to point A1, which is farther from the head end than point A, melt the material from point A1, and move from point A1 to the tail end; S53, repeat S51 and S52; S6, turn off the heating power, cool, turn off the nitrogen, and remove.

Description

Technical Field

[0001] This disclosure relates to the field of material purification, and more specifically to a method for purifying germanium by zone melting. Background Technology

[0002] Zone melting, also known as zone refining, is mainly used for the purification of metals and semiconductor materials. Through localized heating, a small section of solid is melted into a liquid. As the heating coil moves, the molten zone slowly moves from one end of the material to the other. At the end of the molten zone, the melt solidifies. Impurity elements, due to their different solubilities in the solid and liquid phases, accumulate at the beginning and end of the material, respectively. By cutting away a portion of the beginning and end, the middle section yields the material with higher purity.

[0003] Conventional zone melting is unidirectional, meaning it melts from the head to the tail at a certain speed, repeating this process a certain number of times to achieve impurity segregation. However, since over 90% of impurities gradually accumulate at the tail, this method has several limitations. For example, after several unidirectional zone melting cycles, as most impurities continue to segregate towards the tail, the resistivity of the zone-melted germanium ingot gradually decreases from head to tail (resistivity is a crucial indicator of zone-melted germanium ingot quality), resulting in poor resistivity uniformity in the zone-melted product. Furthermore, higher resistivity indicates higher purity; however, because the resistivity of the entire zone-melted product gradually decreases from head to tail (i.e., uneven distribution), the acceptable section of the product is relatively short. Another example is that as the number of zone melting cycles increases, the thickness of the germanium material gradually decreases at the head and gradually increases at the tail, which significantly impacts yield. Summary of the Invention

[0004] In view of the problems existing in the background art, one object of this disclosure is to provide a method for refining germanium by zone melting, which enables the resistivity distribution of the whole zone-melted germanium product to be uniform.

[0005] Another object of this disclosure is to provide a method for refining germanium by zone melting, which can obtain a longer qualified section.

[0006] Another object of this disclosure is to provide a method for refining germanium by zone melting, which enables the entire zone-melted germanium product to have a uniform thickness.

[0007] Therefore, a method for refining germanium by zone melting includes the following steps: S1, surface treatment of germanium material: cleaning the surface of electronic-grade polycrystalline germanium material; S2, furnace loading: loading the germanium material into a graphite boat, loading the graphite boat into the zone melting furnace, sealing the zone melting furnace and purging it with nitrogen; S3, initial single forward zone melting: adjusting the nitrogen flow rate, moving the heating coil to the head of the graphite boat, starting the melting process from the head, and when the germanium material at the head melts into a regular rectangular melting zone, the heating coil begins to move forward from the head to the tail until the heating coil passes the tail of the graphite boat; S4, zone melting one, including sub-steps. Step S41: When the heating coil passes the tail of the graphite boat and the germanium material at the tail is completely solidified, the heating coil moves in the reverse direction, first quickly moving to point B, and starting to melt the germanium material from point B. When the germanium material melts into a regular rectangular molten area, the heating coil begins to move in the reverse direction from point B towards the head until the heating coil passes the head of the graphite boat; Step S42: When the heating coil passes the head of the graphite boat and the germanium material at the head is completely solidified, the heating coil moves in the forward direction, first quickly moving to point A, and starting to melt the germanium material from point A. When the germanium material melts into a regular rectangular molten area, the heating coil begins to move in the forward direction from point A towards the head. S43, repeat sub-steps S41 and S42, performing zone melting a total of 4-6 times in both the forward and reverse directions; S5, zone melting two, including sub-steps: S51, when the heating coil passes the tail of the graphite boat and the germanium material at the tail is completely solidified, the heating coil moves in the reverse direction, first quickly moving to point B1, which is further away from the tail than point B, and starting to melt the material from point B1. When the germanium material melts into a regular rectangular melting zone, the heating coil begins to move in the reverse direction from point B1 towards the head until the heating coil passes the head of the graphite boat; S52, When the heating coil passes the head of the graphite boat and the germanium material at the head is completely solidified, the heating coil moves forward, first quickly moving to point A1, which is further away from the head than point A. From point A1, the material begins to melt. When the germanium material melts into a regular rectangular melting zone, the heating coil begins to move forward from point A1 towards the tail until the heating coil passes the tail of the graphite boat; S53, repeat sub-steps S51 and S52, performing zone melting a total of 3-5 times in both the reverse and forward directions; S6, turn off the heating power, cool, turn off the nitrogen gas, remove the graphite boat from the zone melting furnace, and remove the zone-melted and purified germanium product for testing.

[0008] The beneficial effects of this disclosure are as follows:

[0009] In the zone melting method for purifying germanium disclosed herein, in step S3, the initial single forward zone melting begins with the heating coil at the head of the graphite boat and ends at the tail. In step S4, the first zone melting step begins with the heating coil at point B near the tail of the graphite boat and ends at the head, while in the forward step, the heating coil begins at point A and ends at the tail. Thus, after the first zone melting step in step S4, most impurities are initially separated and concentrated in the head-A and tail-B segments, resulting in a higher purity AB segment. Step S5, the second zone melting step, involves the heating coil moving in the reverse direction, starting at point B1 (farther from the tail end of the graphite boat than point B) and ending at the head of the graphite boat. Moving in the forward direction, the heating coil starts at point A1 (farther from the head end of the graphite boat than point A) and ends at the tail of the graphite boat. This second zone melting step S5 further melts the previously obtained high-purity AB segment, separating impurities from the AB segment into the A-A1 and B-B1 segments, resulting in a high-purity A1-B1 segment with better purity and higher resistivity. Compared to the multiple unidirectional zone melting of germanium materials in the prior art, the zone melting purification method of this disclosure suppresses the phenomenon of gradually decreasing resistivity of the zone-melted germanium material from head to tail, solving the problem of poor resistivity uniformity in the entire zone-melted purified germanium product, and enabling a uniform resistivity distribution throughout the entire zone-melted purified germanium product. Furthermore, it allows for the acquisition of longer qualified segments.

[0010] Compared with the prior art of multiple unidirectional zone melting of germanium material, the zone melting purification method of this disclosure suppresses the phenomenon of germanium material continuously shifting in one direction during the zone melting process, solves the problem of large thickness difference between the beginning and end, and enables the entire zone melting purified germanium product to have uniform thickness. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the process for refining germanium by regional smelting according to this disclosure.

[0012] Figure 2 yes Figure 1 A schematic diagram showing the location of the method for regional smelting and purifying germanium.

[0013] Figure 3 yes Figure 1 A schematic diagram of the test points for testing germanium products obtained through zone melting purification.

[0014] Figure 4 This is a graph showing the resistivity at the test point locations of Example 1 and Comparative Example 1.

[0015] Figure 5 This is a graph showing the thickness at the test point locations of Example 1 and Comparative Example 1. Detailed Implementation

[0016] It will be understood that the disclosed embodiments are merely examples of this disclosure, which can be implemented in various forms. Therefore, the specific details disclosed herein should not be construed as limiting, but are intended only as the basis for the claims and as an illustrative basis to teach those skilled in the art how to implement this disclosure in various ways.

[0017] [Methods for refining germanium through zone smelting]

[0018] Reference Figure 1 and Figure 2 The method for refining germanium by zone smelting according to this disclosure includes the following steps:

[0019] S1, Germanium material surface treatment: Clean the surface of electronic-grade polycrystalline germanium material;

[0020] S2, Furnace loading: Germanium material is loaded into a graphite boat, the graphite boat is loaded into the zone furnace, and nitrogen is introduced after the zone furnace is sealed.

[0021] S3, Initial single forward zone melting: Adjust the nitrogen flow rate, move the heating coil to the head H of the graphite boat, start melting from the head H, and when the germanium material in the head H melts into a regular rectangular melting zone, the heating coil starts to move forward from the head H to the tail T until the heating coil passes the tail T of the graphite boat.

[0022] S4, Zone Melting 1, includes sub-steps:

[0023] S41, when the heating coil passes the tail T of the graphite boat and the germanium material at the tail T is completely solidified, the heating coil moves in the opposite direction, first quickly moving to point B, and starting to melt the material from point B. When the germanium material melts into a regular rectangular melting zone, the heating coil starts to move in the opposite direction from point B to the head H until the heating coil passes the head H of the graphite boat.

[0024] S42, when the heating coil passes through the head H of the graphite boat and the germanium material at the head H is completely solidified, the heating coil moves forward, first quickly to point A, and starts melting from point A. When the germanium material melts into a regular rectangular melting zone, the heating coil starts moving forward from point A to the tail T until the heating coil passes through the tail T of the graphite boat.

[0025] S43, repeat sub-steps S41 and S42, and perform a total of 4-6 zone melts in both the reverse and forward directions;

[0026] S5, Zone Melting II, includes sub-steps:

[0027] S51, when the heating coil passes through the tail T of the graphite boat and the germanium material at the tail T is completely solidified, the heating coil moves in the opposite direction, first quickly moving to point B1, which is further away from the tail T than point B, and starts melting from point B1. When the germanium material melts into a regular rectangular melting area, the heating coil starts moving in the opposite direction from point B1 toward the head H until the heating coil passes through the head H of the graphite boat.

[0028] S52, when the heating coil passes through the head H of the graphite boat and the germanium material at the head H is completely solidified, the heating coil moves forward and first moves quickly to point A1, which is further away from the head H than point A. The material begins to melt from point A1. When the germanium material melts into a regular rectangular melting zone, the heating coil begins to move forward from point A1 to the tail T until the heating coil passes through the tail T of the graphite boat.

[0029] S53, repeat sub-steps S51 and S52, and perform zone melting a total of 3-5 times in both the reverse and forward directions;

[0030] S6, turn off the heating power, cool, turn off the nitrogen, remove the graphite boat from the zone furnace, and take out the zone-melted purified germanium product for testing.

[0031] In the zone melting method for purifying germanium disclosed herein, the initial single forward zone melting in step S3 starts with the heating coil at the head H of the graphite boat and ends at the tail T. In step S4, the first zone melting step involves the heating coil moving in the reverse direction with the heating coil starting at point B near the tail T and ending at the head H; and moving in the forward direction with the heating coil starting at point A and ending at the tail T. Thus, after the first zone melting step in S4, most impurities are initially separated and concentrated in the head HA segment and the tail TB segment, resulting in a higher purity AB segment. Step S5, the second zone melting process, involves the heating coil moving in the reverse direction, starting at point B1 (farther from point B than the tail T) of the graphite boat and ending at the head H of the graphite boat. Moving in the forward direction, the heating coil starts at point A1 (farther from point A than the head H) of the graphite boat and ends at the tail T of the graphite boat. This second zone melting process further melts the previously obtained high-purity AB segment, separating impurities from the AB segment into the A-A1 and B-B1 segments, resulting in a high-purity A1-B1 segment with better purity and higher resistivity. Compared to the multiple unidirectional zone melting of germanium materials in the prior art, the zone melting purification method of this disclosure suppresses the phenomenon of gradually decreasing resistivity of zone-melted germanium materials from beginning to end, solving the problem of poor resistivity uniformity in the entire zone-melted purified germanium product, and enabling a more uniform resistivity distribution throughout the entire zone-melted purified germanium product. Furthermore, it yields a longer, qualified segment.

[0032] Compared with the prior art of multiple unidirectional zone melting of germanium material, the zone melting purification method of this disclosure suppresses the phenomenon of germanium material continuously shifting in one direction during the zone melting process, solves the problem of large thickness difference between the beginning and end, and enables the entire zone melting purified germanium product to have uniform thickness.

[0033] In step S1, in one example, the operation of cleaning the surface of electronic-grade polycrystalline germanium is as follows: prepare 5-6 kg of electronic-grade polycrystalline germanium material with a resistivity greater than 50 Ω·cm, place the electronic-grade polycrystalline germanium in a corrosive liquid with a volume ratio of HNO3:HF = (2-3):1, corrode until the surface is bright, remove it, rinse with pure water for more than 20 minutes, and dry the germanium material with 9N high-purity nitrogen gas.

[0034] In step S2, in one example, the graphite boat is a high-purity graphite boat, and after sealing, it is purified with 9N high-purity nitrogen for more than 2 hours, with a nitrogen flow rate of 4-10 L / h.

[0035] In step S3, in one example, the nitrogen flow rate is adjusted to 4 L / h; the heating coil is an induction coil, and when the heating coil moves to the head H of the graphite boat, the heating power supply of the heating coil is turned on, and the output current of the heating power supply is adjusted to 100-120A, and the melting of the material begins from the head H; the germanium material at the head H melts into a regular rectangular melting zone with a length of 40-60 mm; the moving speed of the heating coil from the head H to the tail T in the positive direction is 100-200 mm / h.

[0036] In sub-step S41, in one example, point B is 60-100mm away from the tail T; the speed at which it first moves quickly to point B is 2000mm / h; the length of the regular rectangular melting zone formed by the melting of germanium material is 40-60mm; and the speed at which the heating coil moves in the opposite direction from point B to the head H is 100-200mm / h.

[0037] In sub-step S42, in one example, point A is 60-100mm away from the head H; the initial speed of moving quickly to point A is 2000mm / h; the length of the regular rectangular melting zone formed by the melting of germanium material is 40-60mm; the speed at which the heating coil begins to move from point A toward the tail T in the positive direction is 100-200mm / h.

[0038] In sub-step S51, in one example, point B1 is 60-100mm away from point B; the speed at which it moves quickly to point B1 is 2000mm / h; the length of the regular rectangular melting zone formed by the melting of germanium material is 40-60mm; and the speed at which the heating coil moves in the opposite direction from point B1 toward head H is 100-200mm / h.

[0039] In sub-step S52, in one example, point A1 is 60-100mm away from point A; the speed at which it moves quickly to point A1 is 2000mm / h; the length of the regular rectangular melting zone formed by the melting of germanium material is 40-60mm; and the speed at which the heating coil moves from point A1 toward the tail T in the positive direction is 100-200mm / h.

[0040] In step S6, in one example, the cooling process lasts 3-4 hours.

[0041] [test]

[0042] Example 1

[0043] Example 1 uses the following steps:

[0044] S1, Germanium material surface treatment: Clean the surface of the electronic grade polycrystalline germanium material. The operation for cleaning the surface of the electronic grade polycrystalline germanium material is as follows: Prepare 5.5 kg of electronic grade polycrystalline germanium material with a resistivity greater than 50 Ω·cm. Place the electronic grade polycrystalline germanium material in an etching liquid with a volume ratio of HNO3:HF = 2.5:1 and etch until the surface is bright. Remove it, rinse with pure water for 25 min, and dry the germanium material with 9N high-purity nitrogen gas.

[0045] S2, Furnace loading: Germanium material is loaded into a graphite boat, the graphite boat is loaded into a zone melting furnace, and nitrogen is purged through the zone melting furnace after sealing. The graphite boat is a high-purity graphite boat, and after sealing, 9N high-purity nitrogen is purged for 2.5 hours at a flow rate of 8L / h.

[0046] S3, Initial Single Forward Zone Melting: Adjust the nitrogen flow rate, move the heating coil to the head H of the graphite boat, and start melting from the head H. When the germanium material at the head H melts into a regular rectangular melting zone, the heating coil starts moving forward from the head H to the tail T until the heating coil passes the tail T of the graphite boat. The nitrogen flow rate is adjusted to 4L / h, the heating coil is an induction coil, and the heating power supply of the heating coil is turned on when the heating coil moves to the head H of the graphite boat. The output current of the heating power supply is adjusted to 110A. Melting begins from the head H. The length of the regular rectangular melting zone at the head H is 50mm, and the moving speed of the heating coil moving forward from the head H to the tail T is 150mm / h.

[0047] S4, Zone Melting 1, uses the following sub-steps:

[0048] S41, when the heating coil passes the tail T of the graphite boat and the germanium material at the tail T is completely solidified, the heating coil moves in the opposite direction, first moving quickly to point B, and starting from point B, the germanium material melts into a regular rectangular molten area. When the germanium material melts into a regular rectangular molten area, the heating coil starts moving in the opposite direction from point B to the head H until the heating coil passes the head H of the graphite boat. Here, the distance between point B and the tail T is 70mm, the speed at which the heating coil moves quickly to point B is 2000mm / h, the length of the regular rectangular molten area of ​​the germanium material is 50mm, and the speed at which the heating coil moves in the opposite direction from point B to the head H is 150mm / h.

[0049] S42, when the heating coil passes through the head H of the graphite boat and the germanium material at the head H is completely solidified, the heating coil moves forward, first quickly to point A, and starts melting from point A. When the germanium material melts into a regular rectangular molten area, the heating coil starts moving forward from point A to the tail T until the heating coil passes through the tail T of the graphite boat. Here, the distance between point A and the head H is 70mm, the speed at which it first moves quickly to point A is 2000mm / h, the length of the regular rectangular molten area of ​​the germanium material is 50mm, and the moving speed of the heating coil moving forward from point A to the tail T is 150mm / h.

[0050] S43, repeat sub-steps S41 and S42, and perform a total of 5 zone melts in both the reverse and forward directions;

[0051] S5, Zone Melting II, uses the following sub-steps:

[0052] S51, when the heating coil passes the tail T of the graphite boat and the germanium material at the tail T is completely solidified, the heating coil moves in the opposite direction, first moving quickly to point B1, which is farther away from the tail T than point B. From point B1, the germanium material begins to melt. When the germanium material melts into a regular rectangular molten area, the heating coil begins to move in the opposite direction from point B1 towards the head H until the heating coil passes the head H of the graphite boat. Here, the distance between point B1 and point B is 70mm. The speed at which the heating coil first moves quickly to point B1 is 2000mm / h. The length of the regular rectangular molten area formed by the germanium material is 50mm. The speed at which the heating coil moves in the opposite direction from point B1 towards the head H is 150mm / h.

[0053] S52, when the heating coil passes through the head H of the graphite boat and the germanium material at the head H is completely solidified, the heating coil moves forward, first quickly moving to point A1, which is farther away from the head H than point A. From point A1, the germanium material begins to melt. When the germanium material melts into a regular rectangular molten area, the heating coil begins to move forward from point A1 towards the tail T until the heating coil passes the tail T of the graphite boat. Here, the distance between point A1 and point A is 70mm. The speed at which the heating coil first moves quickly to point A1 is 2000mm / h. The length of the regular rectangular molten area formed by the germanium material is 50mm. The moving speed of the heating coil from point A1 towards the tail T is 150mm / h.

[0054] S53, repeat sub-steps S51 and S52, and perform a total of 3 zone melts in both the reverse and forward directions;

[0055] S6, turn off the heating power, cool for 3.5 hours, turn off the nitrogen gas, remove the graphite boat from the zone furnace, and take out the zone-melted purified germanium product for testing.

[0056] Comparative Example 1

[0057] Except for omitting steps S4 and S5 and replacing step S3 with 17 unidirectional forward zone melting operations, the rest is the same as in Example 1.

[0058] The germanium products purified by zone melting in Example 1 and Comparative Example 1 were processed according to... Figure 3 The resistivity and thickness of the germanium product refined by zone melting were measured at 10 cm intervals (a total of 10 test points).

[0059] Table 1 shows the resistivity of the zone-melted purified germanium products of Example 1 and Comparative Example 1 at the test points. Table 2 shows the thickness of the zone-melted purified germanium products of Example 1 and Comparative Example 1 at the test points. Figure 4 This is a graph showing the resistivity at the test point locations of Example 1 and Comparative Example 1. Figure 5 This is a graph showing the thickness at the test point locations of Example 1 and Comparative Example 1.

[0060]

[0061]

[0062] From Table 1 and Figure 4 It can be seen that, compared with Comparative Example 1 (i.e., conventional multiple unidirectional zone melting), the special zone melting method of Example 1 suppresses the phenomenon of the resistivity of the zone-melted purified germanium product gradually decreasing from beginning to end, solves the problem of poor resistivity uniformity of the zone-melted purified germanium product, and enables the resistivity of the entire germanium ingot to be uniformly distributed.

[0063] From Table 1 and Figure 4 It can be seen that the resistivity curves of Comparative Example 1 and Example 1 intersect at the position between test point number 4 and test point number 5. From this intersection point to the head H, the resistivity of Comparative Example 1 is greater than that of Example 1. However, from this intersection point to the tail T, the resistivity of Example 1 is greater than that of Comparative Example 1. The ratio of the distance from this intersection point to the tail T to the distance from this intersection point to the head H is approximately 65:45 = 13:9. Combined with... Figure 4In Example 1, the resistivity of the germanium product obtained through melting and purification is uniformly distributed throughout the entire melting zone. Therefore, compared to Comparative Example 1 (i.e., conventional multiple unidirectional zone melting), Example 1 can further increase the length of the qualified section. This indicates that Example 1 can obtain a longer qualified section compared to conventional multiple unidirectional zone melting.

[0064] From Table 2 and Figure 5 It can be seen that, compared with Comparative Example 1 (i.e., conventional multiple unidirectional zone melting), the special zone melting method of Example 1 suppresses the continuous unidirectional shift of germanium material during the zone melting process, solves the problem of large thickness difference between the beginning and end, and enables the entire zone melting purified germanium product to have uniform thickness.

[0065] Several exemplary embodiments have been described in detail above, but this document is not intended to limit itself to the explicitly disclosed combinations. Therefore, unless otherwise stated, the various features disclosed herein can be combined to form several other combinations, which are not shown for simplicity.

Claims

1. A method for purifying germanium by zone melting, characterized in that, Including the following steps: S1, Germanium material surface treatment: Clean the surface of electronic grade polycrystalline germanium material; S2, Furnace loading: Germanium material is loaded into a graphite boat, the graphite boat is loaded into the zone furnace, and nitrogen is introduced after the zone furnace is sealed. S3, Initial single forward zone melting: Adjust the nitrogen flow rate, move the heating coil to the head (H) of the graphite boat, start melting from the head (H), and when the germanium material at the head (H) melts into a regular rectangular melting zone, the heating coil starts moving forward from the head (H) to the tail (T) until the heating coil passes the tail (T) of the graphite boat. S4, Zone Melting 1, includes sub-steps: S41, when the heating coil passes the tail (T) of the graphite boat and the germanium material at the tail (T) is completely solidified, the heating coil moves in the reverse direction, first quickly moving to point B, and starting the melting process from point B. When the germanium material melts into a regular rectangular melting zone, the heating coil begins to move in the opposite direction from point B toward the head (H) until the heating coil passes the head (H) of the graphite boat; S42, when the heating coil passes through the head (H) of the graphite boat and the germanium material at the head (H) is completely solidified, the heating coil moves forward, first quickly to point A, and starts melting from point A. When the germanium material melts into a regular rectangular melting zone, the heating coil starts moving forward from point A to the tail (T) until the heating coil passes through the tail (T) of the graphite boat. S43, repeat sub-steps S41 and S42, and perform a total of 4-6 zone melts in both the reverse and forward directions; S5, Zone Melting II, includes sub-steps: S51, when the heating coil passes the tail (T) of the graphite boat and the germanium material at the tail (T) is completely solidified, the heating coil moves in the opposite direction, first quickly moving to point B1, which is further away from the tail (T) than point B, and starts melting from point B1. When the germanium material melts into a regular rectangular melting zone, the heating coil starts moving in the opposite direction from point B1 toward the head (H) until the heating coil passes the head (H) of the graphite boat. S52, when the heating coil passes through the head (H) of the graphite boat and the germanium material at the head (H) is completely solidified, the heating coil moves forward and first moves quickly to point A1, which is further away from the head (H) than point A. The material begins to melt from point A1. When the germanium material melts into a regular rectangular melting zone, the heating coil begins to move forward from point A1 toward the tail (T) until the heating coil passes through the tail (T) of the graphite boat. S53, repeat sub-steps S51 and S52, and perform zone melting a total of 3-5 times in both the reverse and forward directions; S6, turn off the heating power, cool, turn off the nitrogen, remove the graphite boat from the zone furnace, and take out the zone-melted purified germanium product for testing.

2. The method for refining germanium by zone smelting according to claim 1, characterized in that, In step S1, the surface treatment of the electronic-grade polycrystalline germanium material is performed as follows: Prepare 5-6 kg of electronic-grade polycrystalline germanium material with a resistivity greater than 50 Ω·cm. Place the electronic-grade polycrystalline germanium in a corrosive liquid with a volume ratio of HNO3:HF = (2-3):1 and corrode until the surface is bright. Remove it, rinse it with pure water for more than 20 minutes, and dry the germanium material with 9N high-purity nitrogen gas.

3. The method for refining germanium by zone smelting according to claim 1, characterized in that, In step S2, The graphite boat is a high-purity graphite boat. After sealing, purify with 9N high-purity nitrogen for more than 2 hours, with a nitrogen flow rate of 4-10 L / h.

4. The method for refining germanium by zone smelting according to claim 1, characterized in that, In step S3, Adjust the nitrogen flow rate to 4 L / h; The heating coil is an induction coil. When the heating coil moves to the head (H) of the graphite boat, the heating power supply of the heating coil is turned on. The output current of the heating power supply is adjusted to 100-120A, and the material is melted from the head (H). The germanium material at the head (H) melts into a regular rectangular melting zone with a length of 40-60 mm; The heating coil moves at a speed of 100-200 mm / h from the head (H) to the tail (T) in the forward direction.

5. The method for refining germanium by zone smelting according to claim 1, characterized in that, In substep S41, Point B is 60-100mm away from the tail (T); The initial speed at which the vehicle moves quickly to point B is 2000 mm / h. The length of the regular rectangular melting zone formed by the melting of germanium material is 40-60mm. The heating coil moves in the opposite direction from point B to the head (H) at a speed of 100-200 mm / h.

6. The method for refining germanium by zone smelting according to claim 1, characterized in that, In substep S42, Point A is 60-100mm away from the head (H); The initial speed at which the vehicle moves quickly to point A is 2000 mm / h. The length of the regular rectangular melting zone formed by the melting of germanium material is 40-60mm. The heating coil begins to move from point A towards the tail (T) at a speed of 100-200 mm / h.

7. The method for refining germanium by zone smelting according to claim 1, characterized in that, In sub-step S51, Point B1 is 60-100mm away from point B; First, move quickly to point B1 at a speed of 2000 mm / h; The length of the regular rectangular melting zone formed by the melting of germanium material is 40-60mm. The heating coil moves in the opposite direction from point B1 toward the head (H) at a speed of 100-200 mm / h.

8. The method for refining germanium by zone smelting according to claim 1, characterized in that, In sub-step S52, Point A1 is 60-100mm away from point A; The initial speed for quickly moving to point A1 is 2000 mm / h; The length of the regular rectangular melting zone formed by the melting of germanium material is 40-60mm. The heating coil moves at a speed of 100-200 mm / h from point A1 toward the tail (T) in the positive direction.

9. The method for refining germanium by zone smelting according to claim 1, characterized in that, In step S6, the temperature is cooled for 3-4 hours.

Images