Doping carbon source and vertical boat device

Abstract

The present disclosure provides a doped carbon source and a vertical boat device. The doped carbon source is a mother hollow frustum with both inner and outer diameters axially extending upward and decreasing downward. The mother hollow frustum includes a plurality of sub-hollow frustums that can be stacked axially, with the inner and outer diameters of each sub-hollow frustum being axially extending upward and decreasing downward. The mother hollow frustum is configured such that, upon first use, the multiple sub-hollow frustums are stacked together axially, and upon repeated use, the outermost sub-hollow frustum can be optionally removed. The vertical boat device includes a quartz tube, a quartz center ring, a front PBN crucible, a rear PBN crucible, and a doped carbon source. The quartz tube includes a first hollow frustum segment; the quartz center ring includes a second hollow frustum segment; the front PBN crucible includes a third hollow frustum segment; the rear PBN crucible includes a fourth hollow frustum segment; the doped carbon source is radially sandwiched between the third hollow frustum segment and the first hollow frustum segment and / or the doped carbon source is radially sandwiched between the fourth hollow frustum segment and the second hollow frustum segment.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor material production, and more particularly to a doping carbon source and a vertical boat device for doping carbon into the growth of semi-insulating gallium arsenide crystals. Background Art

[0002] Gallium arsenide (GaAs) is an important III-V compound semiconductor with excellent properties such as a wide bandgap, high electron mobility, and a high electron saturation drift velocity. These properties make GaAs widely used in the manufacture of high-frequency, high-speed, high-temperature, and radiation-resistant microelectronic devices. Furthermore, it is widely used in radar, satellite TV broadcasting, microwave and millimeter-wave communications, wireless communications (represented by mobile phones), and fiber-optic communications. Its direct bandgap properties also allow GaAs to be used in optoelectronics applications such as active optical communication devices (LDs), red and yellow light-emitting diodes (LEDs), visible light lasers, near-infrared lasers, quantum well high-power lasers, and high-efficiency solar cells.

[0003] Currently, commercial methods for mass-producing GaAs single crystals include LEC, VGF, and VB. Because the LEC method produces large variations in the diameter of the ingots and a high dislocation density, the VGF and VB methods are typically used to produce GaAs ingots with low dislocation density. To obtain high-resistance ingots, carbon doping is typically performed during the growth process to compensate for the intrinsic EL2 defects, ultimately achieving high resistance.

[0004] There are two main methods for carbon doping: CO atmosphere doping, as represented by Friberger, and the use of high-purity carbon powder or high-purity graphite blocks as carbon sources. Because atmosphere doping requires high equipment and technical requirements, it significantly increases production costs. The amount of carbon doped into GaAs single crystals during crystal growth is extremely small, making accurate weighing of carbon powder extremely difficult. Furthermore, due to the high surface energy of ultrafine carbon powder, tiny carbon clusters form within the crystal when carbon powder is used for doping. This, on the one hand, causes uneven electrical properties in the crystal, and on the other hand, localized bright spot defects form in the micro-regions of the carbon clusters after the wafer is cut, polished, and washed. In summary, the use of high-purity carbon blocks or graphite blocks as carbon doping sources is more appropriate.

[0005] In addition, the doping carbon source (high-purity carbon block or graphite block) in the prior art can generally only be used once, thereby causing waste of the doping carbon source and increasing costs. Summary of the Invention

[0006] In response to the problems in the prior art, an object of the present disclosure is to provide a doping carbon source and a vertical boat device for doping carbon into the growth of semi-insulating gallium arsenide crystals. The doping carbon source can be reused, thereby reducing costs.

[0007] To this end, the present disclosure provides a doped carbon source for incorporating carbon into the growth of semi-insulating gallium arsenide crystals, wherein the doped carbon source is a mother hollow frustum whose inner and outer diameters are both axially larger at the top and smaller at the bottom; the mother hollow frustum includes a plurality of sub-hollow frustums that can be stacked along the axial direction, wherein the inner and outer diameters of each sub-hollow frustum are formed to be axially larger at the top and smaller at the bottom, and the mother hollow frustum is configured such that, when used for the first time, the plurality of sub-hollow frustums are stacked together along the axial direction for use, and when reused, a sub-hollow frustum located at the outermost end along the axial direction can be optionally removed for use.

[0008] To this end, in some embodiments, the present disclosure provides a vertical boat device for growing semi-insulating gallium arsenide crystals and doping carbon, the vertical boat device comprising a quartz tube, a quartz middle ring, a front-end PBN crucible, a rear-end PBN crucible, and the aforementioned doped carbon source; the quartz tube comprises a first hollow frustum section and a first barrel section, the inner diameter of the first hollow frustum section increases in diameter upward and decreases in diameter downward along the axial direction, and the first barrel section is axially connected to the top of the first hollow frustum section; the quartz middle ring is used to be fixed in the first barrel section of the quartz tube, the quartz middle ring comprises a second hollow frustum section, the inner diameter of the second hollow frustum section increases in diameter upward and decreases in diameter downward along the axial direction; the front-end PBN crucible comprises a third hollow frustum section, and the third hollow frustum section is used to accommodate gallium arsenide The polycrystalline material, the outer diameter of the third hollow frustum segment increases in size at the top and decreases in size at the bottom along the axial direction, and the third hollow frustum segment is used to be located radially spaced apart within the first hollow frustum segment of the quartz tube; the rear-stage PBN crucible includes a fourth hollow frustum segment, the fourth hollow frustum segment is used to accommodate the gallium arsenide polycrystalline material, the outer diameter of the fourth hollow frustum segment increases in size at the top and decreases in size at the bottom along the axial direction, and the fourth hollow frustum segment is used to be located radially spaced apart within the second hollow frustum segment of the quartz middle ring; the doped carbon source is used to be radially sandwiched between the third hollow frustum segment of the front-stage PBN crucible and the first hollow frustum segment of the quartz tube and / or the doped carbon source is used to be radially sandwiched between the fourth hollow frustum segment of the rear-stage PBN crucible and the second hollow frustum segment of the quartz middle ring.

[0009] In some embodiments, the quartz tube further includes a second barrel section, which is axially connected to the bottom of the first hollow frustum section, has an inner diameter smaller than that of the first barrel section, and is closed at its lower axial end. The front-section PBN crucible further includes a third barrel section, which is axially connected to the bottom of the third hollow frustum section, has a closed lower axial end, is used to accommodate a seed crystal, and is used to be radially spaced apart within the second barrel section of the quartz tube.

[0010] In some embodiments, the quartz middle ring further includes a fourth barrel segment, which is radially located outside the second hollow frustum segment and axially connected to the upper end of the second hollow frustum segment at the upper end, and the fourth barrel segment is used to be radially fixed in the first barrel segment of the quartz tube.

[0011] In some embodiments, the front-stage PBN crucible further includes a fifth barrel segment, which is axially connected above the third hollow frustum segment. The upper end of the fifth barrel segment is open in the axial direction. The fifth barrel segment is used to accommodate gallium arsenide polycrystalline material. The fifth barrel segment is used to be radially spaced apart within the first barrel segment of the quartz tube.

[0012] In some embodiments, the inner wall surface of the third hollow frustum segment of the front-stage PBN crucible includes an upper inclined surface, an intermediate transition surface, and a lower inclined surface. The lower inclined surface is radially located outside the extended surface E of the upper inclined surface, and the intermediate transition surface connects the upper inclined surface and the lower inclined surface. When the doping carbon source is used to be radially sandwiched between the third hollow frustum segment of the front-stage PBN crucible and the first hollow frustum segment of the quartz tube, the doping carbon source is radially sandwiched between the lower inclined surface of the third hollow frustum segment of the front-stage PBN crucible and the first hollow frustum segment of the quartz tube, and the intermediate transition surface is used to limit the upward position of the doping carbon source.

[0013] In some embodiments, the rear-stage PBN crucible further includes a sixth barrel segment, which is used for allowing molten gallium arsenide polycrystalline material to pass through. The sixth barrel segment is axially connected below the fourth hollow frustum segment of the rear-stage PBN crucible, and the lower end of the sixth barrel segment is open in the axial direction. The lower end of the sixth barrel segment in the axial direction extends axially downward from the second hollow frustum segment of the quartz middle ring.

[0014] In some embodiments, the rear-stage PBN crucible further includes a seventh barrel segment, which is axially connected above the fourth hollow frustum segment of the rear-stage PBN crucible. The upper end of the seventh barrel segment is open in the axial direction. The seventh barrel segment is used to accommodate gallium arsenide polycrystalline material, and the seventh barrel segment is used to be radially spaced apart within the first barrel segment of the quartz tube.

[0015] In some embodiments, the outer wall surface of the third hollow frustum segment of the front PBN crucible is geometrically similar in shape to the inner wall surface of the first hollow frustum segment of the quartz tube; the outer wall surface of the fourth hollow frustum segment of the rear PBN crucible is geometrically similar in shape to the inner wall surface of the second hollow frustum segment of the quartz middle ring.

[0016] In some embodiments, the upper end of the first barrel section of the quartz tube is open; the vertical boat device further includes a quartz tail cap, which is used to be disposed at the upper end of the first barrel section of the quartz tube to close the first barrel section of the quartz tube.

[0017] The beneficial effects of the present disclosure are as follows: Based on the design of multiple sub-hollow frustums of the doped carbon source, the doped carbon source can be flexibly reused. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of an embodiment of a vertical boat apparatus according to the present disclosure.

[0019] Figure 2 yes Figure 1A schematic perspective view of an embodiment of a doping carbon source of a vertical boat device, wherein the doping carbon source is located at the rear PBN crucible.

[0020] Figure 3 yes Figure 3 A cutaway stereogram of .

[0021] Figure 4 yes Figure 3 sectional view of .

[0022] Figure 5 yes Figure 1 Schematic perspective view of an embodiment of a doping carbon source of a vertical boat device, wherein the doping carbon source is located at the front PBN crucible.

[0023] Figure 6 yes Figure 5 A cutaway stereogram of .

[0024] Figure 7 yes Figure 6 sectional view of .

[0025] Figure 8 yes Figure 1 A perspective view of the quartz mesocircle of the vertical boat apparatus.

[0026] Figure 9 yes Figure 8 A cutaway stereogram of .

[0027] Figure 10 yes Figure 8 sectional view of .

[0028] The description of the accompanying drawings is as follows:

[0029] 100 vertical boat device

[0030] 1 quartz tube

[0031] 11The first hollow cone segment

[0032] 12 First barrel section

[0033] 13 Second barrel section

[0034] 2 quartz middle ring

[0035] 21 Second hollow cone segment

[0036] 22 Fourth barrel section

[0037] 3. Front section PBN crucible

[0038] 31 The third hollow cone segment

[0039] 311 upper inclined surface

[0040] 312 intermediate transition surface

[0041] 313 lower inclined surface

[0042] E Extended Surface

[0043] 32 third barrel section

[0044] 33 Fifth barrel section

[0045] 4. Back-end PBN crucible

[0046] 41 Fourth hollow cone segment

[0047] 42 Sixth tube section

[0048] 43 Seventh tube section

[0049] 5. Doping carbon source

[0050] 51 female hollow cone

[0051] 511 hollow cone

[0052] 6 Quartz tail cap

[0053] S seed crystal

[0054] M GaAs polycrystalline material DETAILED DESCRIPTION

[0055] The accompanying drawings illustrate embodiments of the present disclosure, and it will be understood that the disclosed embodiments are merely examples and that the present disclosure can be implemented in various forms. Therefore, the specific details disclosed herein should not be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one of ordinary skill in the art to implement the present disclosure in various ways.

[0056] In the description of the present disclosure, unless otherwise specified, the terms "first", "second", "third", "fourth", "fifth", "sixth", "seventh", etc. are only used for the purpose of description and component identification, and are not to be understood as relative importance and mutual relationship.

[0057] In the present disclosure, expressions indicating directions such as up, down, left, right, front, and back, etc., used to illustrate the structure and movement of the components of the vertical boat apparatus are not absolute but relative. These expressions are appropriate when the components of the components of the vertical boat apparatus are in the postures shown in the figures. However, when the postures of the components of the vertical boat apparatus change, these expressions should be interpreted differently according to the changes in the postures.

[0058] The vertical boat apparatus 100 according to an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0059] Reference Figure 1In one embodiment, the vertical boat apparatus 100 is used to grow semi-insulating GaAs crystals and dope them with carbon.

[0060] The vertical boat device 100 includes a quartz tube 1 , a quartz center ring 2 , a front-end PBN crucible 3 , a rear-end PBN crucible 4 and a doping carbon source 5 .

[0061] The quartz tube 1 includes a first hollow frustum section 11 and a first barrel section 12. The inner diameter of the first hollow frustum section 11 is larger at the top and smaller at the bottom along the axial direction, and the first barrel section 12 is axially connected to the top of the first hollow frustum section 11. In one embodiment, Figure 1 As shown, the first cylinder section 12 is a cylinder with a constant wall thickness.

[0062] In one embodiment, referring to Figure 1 The quartz tube 1 further includes a second barrel section 13. The second barrel section 13 is axially connected to the lower portion of the first hollow cone section 11. The inner diameter of the second barrel section 13 is smaller than the inner diameter of the first barrel section 12. The lower end of the second barrel section 13 is closed in the axial direction. In one embodiment, Figure 1 As shown, the second cylinder section 13 is a cylinder with uniform wall thickness.

[0063] Reference Figure 1 and Figures 8 to 10 The quartz inner ring 2 is fixed within the first barrel section 12 of the quartz tube 1. The quartz inner ring 2 includes a second hollow frustum section 21, the inner diameter of which increases in diameter upward and decreases in diameter downward along the axial direction. In one embodiment, the second hollow frustum section 21 is fixed to the first barrel section 12 of the quartz tube 1 by welding at its radially upper end (i.e., its largest dimension).

[0064] In one embodiment, referring to Figure 1 and Figures 8 to 10 The quartz middle ring 2 further includes a fourth barrel section 22, which is radially located outside the second hollow frustum section 21 and axially connected to the upper end of the second hollow frustum section 21 at its upper end. The fourth barrel section 22 is used to be radially fixed in the first barrel section 12 of the quartz tube 1. In one embodiment, the fourth barrel section 22 is fixed in the first barrel section 12 of the quartz tube 1 by welding. The fourth barrel section 22 strengthens the positioning stability of the quartz middle ring 2 in the first barrel section 12 of the quartz tube 1, and enables the quartz middle ring 2 to provide sufficient support for the rear-stage PBN crucible 4 and the doping carbon source 5 installed at the quartz middle ring 2. In one embodiment, as Figure 1 As shown, the fourth cylinder section 22 is a cylinder with uniform wall thickness.

[0065] In one embodiment, referring to Figure 1The front-stage PBN crucible 3 includes a third hollow frustum section 31. The third hollow frustum section 31 is used to accommodate the gallium arsenide polycrystalline material M. The outer diameter of the third hollow frustum section 31 increases in diameter upward and decreases in diameter downward along the axial direction. The third hollow frustum section 31 is positioned radially within the first hollow frustum section 11 of the quartz tube 1, spaced apart from the outer diameter. Similarly, the inner diameter of the third hollow frustum section 31 also increases in diameter upward and decreases in diameter downward along the axial direction, thereby facilitating the formation of uniform wall thickness within the third hollow frustum section 31.

[0066] In one embodiment, referring to Figure 1 The outer wall of the third hollow frustum section 31 of the front-stage PBN crucible 3 is geometrically similar in shape to the inner wall of the first hollow frustum section 11 of the quartz tube 1. This facilitates the design of a doping carbon source 5 of equal thickness sandwiched between the outer wall of the third hollow frustum section 31 and the first hollow frustum section 11 of the quartz tube 1, thereby simplifying the design and structure of the doping carbon source 5.

[0067] In one embodiment, referring to Figure 1 The inner wall surface of the third hollow frustum section 31 of the front PBN crucible 3 includes an upper inclined surface 311, an intermediate transition surface 312, and a lower inclined surface 313. The lower inclined surface 313 is radially located outside the extended surface E of the upper inclined surface 311, and the intermediate transition surface 312 connects the upper inclined surface 311 and the lower inclined surface 313. When the doping carbon source 5 is used to be radially sandwiched between the third hollow frustum section 31 of the front PBN crucible 3 and the first hollow frustum section 11 of the quartz tube 1, the doping carbon source 5 is radially sandwiched between the lower inclined surface 313 of the third hollow frustum section 31 of the front PBN crucible 3 and the first hollow frustum section 11 of the quartz tube 1, and the intermediate transition surface 312 is used to limit the upward position of the doping carbon source 5. In one embodiment, referring to Figure 1 In the embodiment, the upper inclined surface 311 and the lower inclined surface 313 are parallel, thereby simplifying the design.

[0068] In one embodiment, referring to Figure 1 The front PBN crucible 3 further includes a third barrel section 32. The third barrel section 32 is axially connected to the lower side of the third hollow frustum section 31. The lower end of the third barrel section 32 is closed in the axial direction. The third barrel section 32 is used to accommodate the seed crystal S. The third barrel section 32 is used to be radially spaced apart from the second barrel section 13 of the quartz tube 1. In one embodiment, Figure 1 As shown, the third cylinder section 32 is a cylinder with a constant wall thickness.

[0069] In one embodiment, referring to Figure 1The front-stage PBN crucible 3 further includes a fifth barrel section 33, which is axially connected to the upper portion of the third hollow frustum section 31. The upper end of the fifth barrel section 33 is open in the axial direction. The fifth barrel section 33 is used to accommodate the gallium arsenide polycrystalline material M. The fifth barrel section 33 is radially spaced apart and located within the first barrel section 12 of the quartz tube 1. The axial length of the fifth barrel section 33 is determined based on the size of the gallium arsenide crystal rod required for actual production. In one embodiment, Figure 1 As shown, the fifth cylinder section 33 is a cylinder with uniform wall thickness.

[0070] Reference Figure 1 The rear-stage PBN crucible 4 includes a fourth hollow frustum-shaped section 41. This section is used to accommodate the gallium arsenide polycrystalline material M. The outer diameter of the fourth hollow frustum-shaped section 41 increases in diameter upward and decreases in diameter downward along the axial direction. The fourth hollow frustum-shaped section 41 is radially spaced apart within the second hollow frustum-shaped section 21 of the quartz tube 1. The fourth hollow frustum-shaped section 41 cooperates with the second hollow frustum-shaped section 21 of the quartz core 2 to radially sandwich the dopant carbon source 5 between the fourth hollow frustum-shaped section 41 of the rear-stage PBN crucible 4 and the second hollow frustum-shaped section 21 of the quartz core 2, when needed. Similarly, the inner diameter of the fourth hollow frustum-shaped section 41 also increases in diameter upward and decreases in diameter downward along the axial direction, thereby facilitating the formation of a uniform wall thickness within the fourth hollow frustum-shaped section 41.

[0071] By using the rear-stage PBN crucible 4 to accommodate the GaAs polycrystalline material M, the front-stage PBN crucible 3 is prevented from directly containing the entire GaAs polycrystalline material M when using the front-stage PBN crucible 3 alone. This would cause the front-stage PBN crucible 3 to bear the entire GaAs polycrystalline material M from beginning to end during the entire semi-insulating GaAs crystal growth process, resulting in a shortened service life of the front-stage PBN crucible 3. By using the rear-stage PBN crucible 4 to accommodate a portion of the entire GaAs polycrystalline material M during the entire semi-insulating GaAs crystal growth process, the front-stage PBN crucible 3 can bear a gradually increasing amount of GaAs polycrystalline material M until it bears the entire GaAs polycrystalline material M, thereby extending the service life of the front-stage PBN crucible 3.

[0072] In one embodiment, referring to Figure 1 The outer wall of the fourth hollow frustum section 41 of the rear-stage PBN crucible 4 and the inner wall of the second hollow frustum section 21 of the quartz center ring 2 are geometrically similar in shape. This facilitates the design of a carbon doping source 5 of equal thickness sandwiched between the fourth hollow frustum section 41 of the rear-stage PBN crucible 4 and the second hollow frustum section 21 of the quartz center ring 2, thereby simplifying the design and structure of the carbon doping source 5.

[0073] In one embodiment, referring to Figure 1The rear PBN crucible 4 further includes a sixth barrel section 42. The sixth barrel section 42 is used to allow the molten gallium arsenide polycrystalline material M to pass through. The sixth barrel section 42 is axially connected to the bottom of the fourth hollow frustum section 41 of the rear PBN crucible 4. The lower end of the sixth barrel section 42 is open in the axial direction, and the lower end of the sixth barrel section 42 extends axially downward from the second hollow frustum section 21 of the quartz middle ring 2. On the one hand, the sixth barrel section 42 is used to downwardly supply the molten gallium arsenide polycrystalline material M from the front PBN crucible 3 during the growth of the semi-insulating gallium arsenide crystal. On the other hand, it serves to stop the doping carbon source 5 sandwiched between the fourth hollow frustum section 41 of the rear PBN crucible 4 and the second hollow frustum section 21 of the quartz middle ring 2 from moving downward, thereby enhancing the positioning of the doping carbon source 5. In one embodiment, as Figure 1 As shown, the sixth cylinder section 42 is a cylinder with a constant wall thickness.

[0074] In one embodiment, referring to Figure 1 The rear-stage PBN crucible 4 further includes a seventh barrel section 43, which is axially connected to the top of the fourth hollow frustum section 41 of the rear-stage PBN crucible 4. The upper end of the seventh barrel section 43 is open in the axial direction. The seventh barrel section 43 is used to accommodate gallium arsenide polycrystalline material M. The seventh barrel section 43 is used to be located in the first barrel section 12 of the quartz tube 1 at intervals in the radial direction. The seventh barrel section 43 can store enough gallium arsenide polycrystalline material M to meet the size and volume of gallium arsenide crystal rods required for actual production of the front-stage PBN crucible 3. The total gallium arsenide polycrystalline material M accommodated in the rear-stage PBN crucible 4 is sufficient to meet the axial height of the gallium arsenide crystal rod grown in the front-stage PBN crucible 3 below the lowermost end of the rear-stage PBN crucible 4. In one embodiment, as Figure 1 As shown, the seventh cylinder section 43 is a cylinder with uniform wall thickness.

[0075] The doping carbon source 5 is used to dope carbon into the growth of the semi-insulating gallium arsenide crystal.

[0076] Reference Figure 1 and Figures 2 to 7 The doping carbon source 5 is used to be sandwiched radially between the third hollow frustum section 31 of the front PBN crucible 3 and the first hollow frustum section 11 of the quartz tube 1 and / or the doping carbon source 5 is used to be sandwiched radially between the fourth hollow frustum section 41 of the rear PBN crucible 4 and the second hollow frustum section 21 of the quartz middle ring 2. Figure 1 middle, Figure 1 In the figure, one doping carbon source 5 is radially sandwiched between the third hollow frustum section 31 of the front PBN crucible 3 and the first hollow frustum section 11 of the quartz tube 1, while another doping carbon source 5 is radially sandwiched between the fourth hollow frustum section 41 of the rear PBN crucible 4 and the second hollow frustum section 21 of the quartz center ring 2. This is not limiting, and the doping carbon source 5 can be placed in only one of the two aforementioned locations depending on actual production conditions.

[0077] In one embodiment, referring to Figures 2 to 7 The doped carbon source 5 is a mother hollow frustum 51, whose inner and outer diameters are both axially larger and smaller at the bottom. The mother hollow frustum 51 includes a plurality of axially stackable sub-hollow frustums 511, each of which has an inner and outer diameter that is axially larger and smaller at the bottom. The mother hollow frustum 51 is configured such that, when used for the first time, the plurality of sub-hollow frustums 511 are stacked together in the axial direction, and when reused, the sub-hollow frustum 511 located at the outermost end (e.g., the uppermost or lowermost end) in the axial direction can be optionally removed for reuse. Note that, when reused, the sub-hollow frustum 511 located at the uppermost end in the axial direction, i.e., the sub-hollow frustum 511 with the largest or smallest inner diameter, can be optionally removed, so that the remaining sub-hollow frustums 511 remain stacked continuously, thereby facilitating the positioning stability of the remaining sub-hollow frustums 511 of the mother hollow frustum 51. Furthermore, in one embodiment, the number of sub-hollow frustums 511 can be divided equidistantly based on the generatrix of the inner wall of the mother hollow frustum 51, or divided by equal weight based on the generatrix of the inner wall of the mother hollow frustum 51, or divided based on the desired weight of each sub-hollow frustum 511 (i.e., each sub-hollow frustum 511 is completely different or not completely the same). The number of sub-hollow frustums 511 is not limited to the three shown in the figure; two or more than three can also be used. Thus, the design of multiple sub-hollow frustums 511 of the doping carbon source 5 allows for flexible reuse of the doping carbon source 5. By dividing the carbon source 5 into multiple sub-hollow frustums 511, it is possible to reasonably control the range of carbon doping.

[0078] In one embodiment, the inner and outer walls of the plurality of circumferentially stacked sub-hollow frustums form a smooth, continuous wall of the mother hollow frustum. In other words, the generatrix of the inner and outer circumferential surfaces of the mother hollow frustum is a straight line or a smooth curve.

[0079] Regardless of whether the doped carbon source 5 is used for the first time or is subsequently reused, the outer diameter of the sub-hollow cone 511 of the mother hollow cone 51 of the doped carbon source 5 is designed so that: when the doped carbon source 5 is used to be radially clamped between the third hollow cone segment 31 of the front-stage PBN crucible 3 and the first hollow cone segment 11 of the quartz tube 1, any sub-hollow cone 511 of the doped carbon source 5 will not fall out of the first hollow cone segment 11 of the quartz tube 1; when the doped carbon source 5 is used to be radially clamped between the fourth hollow cone segment 41 of the rear-stage PBN crucible 4 and the second hollow cone segment 21 of the quartz middle ring 2, any sub-hollow cone 511 of the doped carbon source 5 will not fall out of the second hollow cone segment 21 of the quartz middle ring 2.

[0080] In one embodiment, for the doping carbon source 5 in the front-stage PBN crucible 3, the inner and outer walls of the mother hollow frustum 51, the outer wall of the third hollow frustum segment 31, and the inner wall of the first hollow frustum segment 11 of the quartz tube 1 are geometrically similar in shape. In another embodiment, for the doping carbon source 5 in the rear-stage PBN crucible 4, the inner and outer walls of the mother hollow frustum 51, the outer wall of the fourth hollow frustum segment 41 of the rear-stage PBN crucible 4, and the inner wall of the second hollow frustum segment 21 of the quartz center ring 2 are geometrically similar in shape. This simplifies and facilitates installation of the doping carbon source 5, improving positioning accuracy and stability.

[0081] The shape of the quartz tube 1 including the first hollow frustum section 11, the first barrel section 12 and the second barrel section 13 when the generatrix of the inner wall surface of the first hollow frustum section 11 is a single oblique straight line is the shape currently commonly used in the industry. Based on the shape design of the doped carbon source 5 disclosed in the present invention, the currently commonly used quartz tube 1 can be directly adopted, thereby simplifying the overall design of the vertical boat device 100 and reducing costs.

[0082] The material of the doping carbon source 5 is graphite with a purity of 5N or higher.

[0083] When the doped carbon source 5 is reused, it is cleaned and dried.

[0084] In one embodiment, the cleaning process includes the following steps: Step S1: hydrofluoric acid immersion; Step S2: pure water rinsing; and Step S3: alcohol immersion. In one embodiment, in Step S1, the hydrofluoric acid immersion time is 3 to 5 minutes. In one embodiment, in Step S3, the alcohol immersion time is 1 to 2 hours.

[0085] In one embodiment, drying includes the following steps: Step S4: natural air drying until no moisture is present on the surface of the doped carbon source 5; Step S5: drying in a nitrogen cabinet; and Step S6: vacuum drying. In one embodiment, in Step S5, drying is performed at 80-120°C for 1-2 hours. In Step S6, drying is performed at 400-700°C for 1-2 hours.

[0086] In one embodiment, referring to Figure 1 , the upper end of the first barrel section 12 of the quartz tube 1 is open; the vertical boat device 100 also includes a quartz tail cap 6, which is used to be arranged at the upper end of the first barrel section 12 of the quartz tube 1 to close the first barrel section 12 of the quartz tube 1.

[0087] Next, based on Figure 1 The overall structure is given to illustrate the assembly process of the vertical boat device 100.

[0088] When the doping carbon source 5 is only used to be radially sandwiched between the third hollow frustum section 31 of the front PBN crucible 3 and the first hollow frustum section 11 of the quartz tube 1: provide a quartz tube 1; put the doping carbon source 5 into the quartz tube 1, and the doping carbon source 5 falls on the first hollow frustum section 11 of the quartz tube 1; install the front PBN crucible 3 into the quartz tube 1, and the doping carbon source 5 is radially sandwiched between the third hollow frustum section 31 of the front PBN crucible 3 and the first hollow frustum section 11 of the quartz tube 1; load the seed crystal into the third barrel section 32 of the front PBN crucible 3, and then load the gallium arsenide polycrystalline material M into the fifth barrel section 33 of the front PBN crucible 3; load the quartz middle ring 2 into The first barrel section 22 of the quartz tube 1 is fixed radially to the first barrel section 12 of the quartz tube 1 by welding. The rear-stage PBN crucible 4 is installed in the first barrel section 22 of the quartz tube 1. The fourth hollow frustum section 41 of the rear-stage PBN crucible 4 is radially abutted against the second hollow frustum section 21 of the quartz middle ring 2. The lower end of the sixth barrel section 42 extends axially downward from the second hollow frustum section 21 of the quartz middle ring 2. Gallium arsenide polycrystalline material M is installed in the seventh barrel section 43 of the rear-stage PBN crucible 4. The quartz tail cap 6 is set at the upper end of the first barrel section 12 of the quartz tube 1 and the first barrel section 12 of the quartz tube 1 is sealed by welding.

[0089] When the doping carbon source 5 is only used to be radially sandwiched between the fourth hollow frustum section 41 of the rear PBN crucible 4 and the second hollow frustum section 21 of the quartz middle ring 2: provide a quartz tube 1; install the front PBN crucible 3 into the quartz tube 1, and radially abut the third hollow frustum section 31 of the front PBN crucible 3 against the first hollow frustum section 11 of the quartz tube 1; install the seed crystal into the third barrel section 32 of the front PBN crucible 3, and then install the gallium arsenide polycrystalline material M into the fifth barrel section 33 of the front PBN crucible 3; install the quartz middle ring 2 into the first barrel section 22 of the quartz tube 1, and radially fix the fourth barrel section 22 of the quartz middle ring 2 into the first barrel section 12 of the quartz tube 1 by welding. ; Place the doped carbon source 5 into the quartz tube 1, and the doped carbon source 5 falls on the second hollow frustum section 21 of the quartz middle ring 2; install the rear-stage PBN crucible 4 into the first barrel section 22 of the quartz tube 1, and the doped carbon source 5 is radially sandwiched between the fourth hollow frustum section 41 of the rear-stage PBN crucible 4 and the second hollow frustum section 21 of the quartz middle ring 2, and the lower end of the sixth barrel section 42 of the rear-stage PBN crucible 4 extends axially downward from the second hollow frustum section 21 of the quartz middle ring 2; load the gallium arsenide polycrystalline material M into the seventh barrel section 43 of the rear-stage PBN crucible 4; set the quartz tail cap 6 at the upper end of the first barrel section 12 of the quartz tube 1 and seal the first barrel section 12 of the quartz tube 1 by welding.

[0090] When the doping carbon source 5 is used to be radially sandwiched between the third hollow frustum section 31 of the front PBN crucible 3 and the first hollow frustum section 11 of the quartz tube 1, and the doping carbon source 5 is used to be radially sandwiched between the fourth hollow frustum section 41 of the rear PBN crucible 4 and the second hollow frustum section 21 of the quartz middle ring 2: provide a quartz tube 1; put the doping carbon source 5 into the quartz tube 1, and the doping carbon source 5 falls on the first hollow frustum section 11 of the quartz tube 1; load the front PBN crucible 3 into the quartz tube 1, and the doping carbon source 5 is radially sandwiched between the third hollow frustum section 31 of the front PBN crucible 3 and the first hollow frustum section 11 of the quartz tube 1; load the seed crystal into the third barrel section 32 of the front PBN crucible 3, and then load the gallium arsenide polycrystalline material M into the fifth barrel section 33 of the front PBN crucible 3; load the quartz middle ring 2 into the quartz tube 1; The first barrel section 22 of the tube 1 is fixed radially by welding the fourth barrel section 22 of the quartz middle ring 2 within the first barrel section 12 of the quartz tube 1. The doped carbon source 5 is placed in the quartz tube 1 and falls on the second hollow frustum section 21 of the quartz middle ring 2. The rear-stage PBN crucible 4 is loaded into the first barrel section 22 of the quartz tube 1 and radially sandwiched between the fourth hollow frustum section 41 of the rear-stage PBN crucible 4 and the second hollow frustum section 21 of the quartz middle ring 2. The lower end of the sixth barrel section 42 of the rear-stage PBN crucible 4 extends axially downward from the second hollow frustum section 21 of the quartz middle ring 2. Gallium arsenide polycrystalline material M is loaded into the seventh barrel section 43 of the rear-stage PBN crucible 4. The quartz tail cap 6 is set at the upper end of the first barrel section 12 of the quartz tube 1 and sealed by welding.

[0091] Note that in the three aforementioned cases, the seed crystal is loaded into the third barrel section 32 of the front-stage PBN crucible 3, and then the gallium arsenide polycrystalline material M is loaded into the fifth barrel section 33 of the front-stage PBN crucible 3 before the front-stage PBN crucible 3 is loaded into the quartz tube 1. Similarly, the gallium arsenide polycrystalline material M is loaded into the seventh barrel section 43 of the rear-stage PBN crucible 4 before the rear-stage PBN crucible 4 is loaded into the first barrel section 22 of the quartz tube 1.

[0092] It is also noted that boron oxide is added simultaneously when the gallium arsenide polycrystalline material M is loaded. After the gallium arsenide crystal is completed, the quartz tube 1 is knocked open, and the front-stage PBN crucible 3 and the rear-stage PBN crucible 4 are taken out. The rear-stage PBN crucible 4 can be reused. The gallium arsenide crystal is removed from the front-stage PBN crucible 3 by soaking the front-stage PBN crucible 3 in methanol, thereby realizing the reuse of the front-stage PBN crucible 3.

[0093] Finally, the testing process is given.

[0094] The first set of embodiments

[0095] Using 10 kg of 7N GaAs polycrystal as the raw material, a 4-inch semi-insulating crystal rod was grown. The weight of the doped carbon source 5 was 9 g. During the charging process, the doped carbon source 5 (the number of sub-hollow cones 511 was 3, and the weights of the sub-hollow cones 511 from top to bottom along the axial direction were 2.5 g, 3 g, and 3.5 g, respectively) was placed in the front-stage PBN crucible 3. After the crystal growth was completed, the conical portion and the tail cap were removed and the outer circle was ground. After the treatment, samples were taken from the head near the seed crystal end (hereinafter referred to as the head sample) and the tail at the other end (hereinafter referred to as the tail sample) to test the relevant electrical performance parameters. The electrical performance data of this crystal rod are numbered 1# in Table 1.

[0096] The charging weight and specifications of the doping carbon source 5 are the same as those of the 1# crystal rod. The doping carbon source 5 is placed in the rear PBN crucible 4. After the crystal growth is completed, the head and tail of the crystal rod are taken for electrical performance testing. The test results are numbered 2# in Table 1.

[0097] The charging weight was kept the same as that of the 1# ingot. The doping carbon source 5 was used for the second time after cleaning. After the crystal growth was completed, samples were taken from the head and tail of the equal diameter part of the ingot for testing. The test results are numbered 3# in Table 1.

[0098] The charging weight was kept the same as that of the 1# crystal rod. The doped carbon source 5 was used for the second time after being cleaned. A portion of the original doped carbon source 5 was removed so that the total weight of the doped carbon source 5 during charging was 6.5 g. The doped carbon source 5 was placed in the front PBN crucible 3. After the crystal growth was completed, samples were taken from the head and tail of the equal-diameter part of the crystal rod for electrical performance testing. The test results are numbered 4# in Table 1.

[0099] Table 1 Relationship between carbon source and electrical properties of 4-inch GaAs doped crystals

[0100]

[0101] Note that in Table 1, the weight is measured using an ordinary balance. Since the amount of carbon doping is extremely small (approximately several micrograms), no weight change is observed when measured using an ordinary balance on site.

[0102] Second set of embodiments

[0103] Using 15 kg of 7N GaAs polycrystal as the raw material, a 6-inch semi-insulating crystal ingot was grown. The weight of the doped carbon source 5 was 16 g (the number of sub-hollow cones 511 was 5, and according to the required weight of each sub-hollow cone 511, the weights of the sub-hollow cones 511 from top to bottom along the axial direction were 2.5 g, 2.5 g, 3 g, 3.5 g, and 4.5 g). During charging, the doped carbon source 5 was placed in the front PBN crucible 3. After the crystal growth was completed, the tapered portion and the tail cap were removed and the outer diameter was ground. After the treatment, samples were taken from the head near the seed crystal end (hereinafter referred to as the head sample) and the tail at the other end (hereinafter referred to as the tail sample) to test the relevant electrical properties. The electrical performance data of this crystal ingot are numbered 1# in Table 2.

[0104] The charging weight and the specifications of the doped carbon source 5 are kept the same as those of the 1# crystal rod. The doped carbon source 5 is placed in the rear PBN crucible 4. After the crystal growth is completed, the head and tail of the crystal rod are taken for electrical performance testing. The test results are numbered 2# in Table 2.

[0105] The charging weight was kept the same as that of the 1# ingot. The doping carbon source 5 was used for the second time after cleaning. After the crystal growth was completed, samples were taken from the head and tail of the equal diameter part of the ingot for testing. The test results are numbered 3# in Table 2.

[0106] The charging weight was kept the same as that of the 1# crystal rod. The doped carbon source 5 was used for the second time after being cleaned. A portion of the original doped carbon source 5 was removed to keep the total weight of the doped carbon source 5 at the time of charging at 13.5 g. The doped carbon source 5 was placed in the front-stage PBN crucible 3. After the crystal growth was completed, samples were taken from the head and tail of the equal-diameter part of the crystal rod for testing electrical performance data. The test results are numbered 4# in Table 2.

[0107] The charging weight was kept the same as that of the 1# crystal rod. The doped carbon source 5 that was used for the third time after cleaning was used. A portion of the entire doped carbon source 5 of 4# was removed to keep the total weight of the doped carbon source 5 at the time of charging at 11 g. The doped carbon source 5 was placed in the front-stage PBN crucible 3. After the crystal growth was completed, samples were taken from the head and tail of the equal-diameter part of the crystal rod for electrical performance testing. The test results are numbered 5# in Table 2.

[0108] Table 2 Relationship between 6-inch GaAs doped carbon source and crystal electrical properties

[0109]

[0110]

[0111] The measurement results of the two sets of embodiments show that for the same number of uses, the same doping carbon source 5 (i.e., the number of sub-hollow cones 511 remains unchanged), and the same crystal location, the different placement positions of the doping carbon source 5 have an impact on the amount of carbon doping. Due to the existence of the temperature gradient, the thermal convection is stronger at the location of the rear section, and the amount of carbon doped in the rear section will be greater than the amount of carbon doped in the front section. Therefore, the resistivity of the rear section is slightly higher, while the changes in electron mobility and resistivity are exactly the opposite.

[0112] For the same doped carbon source 5 (i.e., the number of sub-hollow cones 511 remains unchanged), the same placement position, and the same crystal part, but different times of use, the amount of carbon doped when used again will be greater than the amount of carbon doped when used previously, that is, the resistivity when used again is greater than the resistivity when used previously. This is because the internal structure of the doped carbon source 5 changes after repeated use.

[0113] For the same placement position and the same crystal part, different doping carbon sources 5 (i.e., the number of sub-hollow cones 511) and different times of use, after repeated use, as the number of uses increases and the weight of the doped carbon source 5 continues to decrease, the amount of doped carbon decreases compared to the case where the weight does not decrease after repeated use, but gradually approaches the amount of doped carbon at the first use, see the comparison of the results of 1#, 3# and 4# in Table 1 and the comparison of the results of 1#, 3#, 4# and 5# in Table 2. In this way, the range stability of the amount of doped carbon can be achieved.

[0114] The above detailed description describes multiple exemplary embodiments, but this document is not intended to be limited to the explicitly disclosed combinations. Therefore, unless otherwise stated, the various features disclosed herein can be combined to form multiple additional combinations that are not shown for the sake of simplicity.

Claims

1. A doping carbon source (5) for doping carbon into semi-insulating gallium arsenide crystal growth, characterized in that: The doped carbon source (5) is a female hollow frustum (51) with both inner and outer diameters increasing in the axial direction and decreasing in the axial direction. The mother hollow frustum (51) comprises a plurality of physically detachable and independently stackable sub-hollow frustums (511) along the axial direction. The inner diameter and outer diameter of each sub-hollow frustum (511) are formed to be larger at the top and smaller at the bottom along the axial direction. The mother hollow frustum (51) is configured such that, when used for the first time, a plurality of sub-hollow frustums (511) are stacked together in the axial direction to provide a doping carbon source, and when used repeatedly, the sub-hollow frustum (511) located at the outermost end in the axial direction is removed for use.

2. A vertical boat apparatus (100) for growing semi-insulating gallium arsenide crystals and incorporating carbon, characterized in that: The vertical boat device (100) comprises a quartz tube (1), a quartz middle ring (2), a front-end PBN crucible (3), a rear-end PBN crucible (4), and a doping carbon source (5) according to claim 1; The quartz tube (1) comprises a first hollow frustum section (11) and a first barrel section (12); the inner diameter of the first hollow frustum section (11) increases in diameter at the top and decreases in diameter at the bottom along the axial direction; and the first barrel section (12) is connected to the top of the first hollow frustum section (11) along the axial direction; The quartz middle ring (2) is used to be fixed in the first barrel section (12) of the quartz tube (1). The quartz middle ring (2) includes a second hollow frustum section (21). The inner diameter of the second hollow frustum section (21) increases in diameter upward and decreases in diameter downward along the axial direction. The front-stage PBN crucible (3) comprises a third hollow frustum section (31), the third hollow frustum section (31) is used to accommodate gallium arsenide polycrystalline material (M), the outer diameter of the third hollow frustum section (31) is larger in the upper part and smaller in the lower part along the axial direction, and the third hollow frustum section (31) is used to be located in the first hollow frustum section (11) of the quartz tube (1) at intervals in the radial direction; The rear section PBN crucible (4) comprises a fourth hollow frustum section (41), the fourth hollow frustum section (41) is used to accommodate gallium arsenide polycrystalline material (M), the outer diameter of the fourth hollow frustum section (41) is larger in the upper part and smaller in the lower part along the axial direction, and the fourth hollow frustum section (41) is used to be located in the second hollow frustum section (21) of the quartz middle ring (2) at intervals in the radial direction; The doped carbon source (5) is used to be radially sandwiched between the third hollow frustum section (31) of the front PBN crucible (3) and the first hollow frustum section (11) of the quartz tube (1) and / or the doped carbon source (5) is used to be radially sandwiched between the fourth hollow frustum section (41) of the rear PBN crucible (4) and the second hollow frustum section (21) of the quartz middle ring (2).

3. The vertical boat device (100) according to claim 2, characterized in that The quartz tube (1) further comprises a second barrel section (13), the second barrel section (13) being axially connected to the lower side of the first hollow frustum section (11), the inner diameter of the second barrel section (13) being smaller than the inner diameter of the first barrel section (12), and the lower end of the second barrel section (13) being closed in the axial direction; The front-stage PBN crucible (3) further includes a third barrel section (32), which is axially connected to the bottom of the third hollow frustum section (31), and the lower end of the third barrel section (32) is closed in the axial direction. The third barrel section (32) is used to accommodate the seed crystal (S), and the third barrel section (32) is used to be located in the second barrel section (13) of the quartz tube (1) at intervals in the radial direction.

4. The vertical boat device (100) according to claim 2, characterized in that The quartz middle ring (2) further includes a fourth barrel section (22), which is radially located outside the second hollow frustum section (21) and axially connected to the upper end of the second hollow frustum section (21) at its upper end. The fourth barrel section (22) is used to be radially fixed within the first barrel section (12) of the quartz tube (1).

5. The vertical boat device (100) according to claim 2, characterized in that The front-stage PBN crucible (3) further includes a fifth barrel section (33), which is axially connected to the upper side of the third hollow frustum section (31), and the upper end of the fifth barrel section (33) is open in the axial direction. The fifth barrel section (33) is used to accommodate gallium arsenide polycrystalline material (M), and the fifth barrel section (33) is used to be located in the first barrel section (12) of the quartz tube (1) at intervals in the radial direction.

6. The vertical boat device (100) according to claim 2, characterized in that The inner wall surface of the third hollow frustum section (31) of the front PBN crucible (3) comprises an upper inclined surface (311), an intermediate transition surface (312) and a lower inclined surface (313), wherein the lower inclined surface (313) is radially located outside an extended surface (E) of the upper inclined surface (311), and the intermediate transition surface (312) connects the upper inclined surface (311) and the lower inclined surface (313); When the doping carbon source (5) is used to be clamped radially between the third hollow frustum section (31) of the front PBN crucible (3) and the first hollow frustum section (11) of the quartz tube (1), the doping carbon source (5) is clamped radially between the lower inclined surface (313) of the third hollow frustum section (31) of the front PBN crucible (3) and the first hollow frustum section (11) of the quartz tube (1), and the intermediate transition surface (312) is used to limit the upward position of the doping carbon source (5).

7. The vertical boat device (100) according to claim 2, characterized in that The rear section PBN crucible (4) further comprises a sixth barrel section (42), which is used for allowing molten gallium arsenide polycrystalline material (M) to pass through. The sixth barrel section (42) is axially connected below the fourth hollow frustum section (41) of the rear section PBN crucible (4). The lower end of the sixth barrel section (42) is open in the axial direction, and the lower end of the sixth barrel section (42) extends axially downward from the second hollow frustum section (21) of the quartz middle ring (2).

8. The vertical boat device (100) according to claim 2, characterized in that The rear section PBN crucible (4) further includes a seventh barrel section (43), which is axially connected above the fourth hollow frustum section (41) of the rear section PBN crucible (4), and the upper end of the seventh barrel section (43) is open in the axial direction. The seventh barrel section (43) is used to accommodate gallium arsenide polycrystalline material (M), and the seventh barrel section (43) is used to be located in the first barrel section (12) of the quartz tube (1) at intervals in the radial direction.

9. The vertical boat device (100) according to claim 2, characterized in that: The outer wall surface of the third hollow frustum section (31) of the front PBN crucible (3) and the inner wall surface of the first hollow frustum section (11) of the quartz tube (1) are geometrically similar in shape; The outer wall surface of the fourth hollow frustum section (41) of the rear PBN crucible (4) and the inner wall surface of the second hollow frustum section (21) of the quartz middle ring (2) are geometrically similar in shape.

10. The vertical boat device (100) according to claim 2, characterized in that: The upper end of the first barrel section (12) of the quartz tube (1) is open; The vertical boat device (100) further includes a quartz tail cap (6), The quartz tail cap (6) is used to be arranged on the upper end of the first barrel section (12) of the quartz tube (1) to close the first barrel section (12) of the quartz tube (1).

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