A semiconductor resistivity measuring device at liquid nitrogen temperature

Abstract

This invention discloses a semiconductor resistivity measurement device at liquid nitrogen temperature. The device includes: a mounting base plate, a sample holder, a probe module, a sliding stage module, a fixed vertical plate, a first indium sheet, a second indium sheet, a first copper electrode, a second copper electrode, a first insulating liner, a second insulating liner, and a sample pressurization movable module. The sliding stage module is connected to the probe module, which is equipped with multiple wedge-shaped probes. The fixed vertical plate is sequentially connected to the first insulating liner, the first copper electrode, and the first indium sheet. The sample pressurization movable module is connected to the electrode fixing plate, which is sequentially connected to the second insulating liner, the second copper electrode, and the second indium sheet. The first and second indium sheets are respectively positioned at the end face of the sample to be measured. The sample holder and the probe module are respectively positioned at the crystal plane of the sample to be measured. This invention uses a spring plate to pressurize the wedge-shaped probes, ensuring good contact between the wedge-shaped probes and the sample at low temperatures. It eliminates the need for slicing and sample preparation, and quickly obtains the resistivity distribution results of the entire single crystal.

Description

Technical Field

[0001] This invention relates to the field of low-temperature testing technology for semiconductor samples, and more specifically to a semiconductor resistivity measuring device at liquid nitrogen temperature. Background Technology

[0002] Since germanium detectors must operate at low temperatures, it is necessary to measure the main physical properties of germanium single crystals—resistivity and carrier concentration—at low temperatures. Existing germanium single crystal resistivity measuring devices cannot measure the resistivity and carrier concentration of the entire single crystal at 77°K (i.e., at liquid nitrogen temperature). Each time, a thin slice with a thickness of 1 mm can only be cut vertically from the part of the single crystal to be measured along the longitudinal direction. This slice is then cut into smaller slices of approximately 8 mm × 8 mm. Electrodes and leads are soldered onto the slices, which are then installed on the resistivity measuring device, placed in a Dewar flask, and liquid nitrogen is poured in before measuring the resistivity and carrier concentration.

[0003] As can be seen from the above, existing test samples require several cuts to form, which is a destructive measurement for single crystals. In addition, electrodes and leads need to be soldered, making the process cumbersome, labor-intensive, and time-consuming. Furthermore, only local resistivity results can be obtained. If the resistivity of a single crystal from beginning to end is required, the entire single crystal must be sliced, which is extremely labor-intensive and makes it difficult to quickly obtain the resistivity distribution of the entire single crystal. This is not conducive to the analysis and improvement of the high-purity germanium single crystal growth process. Summary of the Invention

[0004] To overcome the defects and shortcomings of existing technologies, this invention provides a semiconductor resistivity measurement device at liquid nitrogen temperature. The wedge probe of this invention contacts the single crystal through a sample pressurization module. Each wedge probe has a pressure-adjustable spring plate to pressurize the wedge probe, ensuring good contact between the wedge probe and the sample at low temperature. The resistivity distribution of a whole high-purity germanium single crystal at liquid nitrogen temperature can be obtained quickly without the need for slicing and sample preparation.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The present invention provides a semiconductor resistivity measuring device at liquid nitrogen temperature, comprising: a mounting base plate, a sample holder, a probe module, a slide module, a fixed vertical plate, a first indium sheet, a second indium sheet, a first copper electrode, a second copper electrode, a first insulating liner, a second insulating liner, and a sample pressurization movable module;

[0007] The probe module is equipped with multiple wedge-shaped probes, which are used to contact the crystal surface of the sample to be tested;

[0008] The sample holder, the fixed vertical plate, and the sample pressurization movable module are respectively connected to the mounting base plate, and the slide module is connected to the probe module;

[0009] One side of the fixed vertical plate is connected to one side of the first insulating liner, the other side of the first insulating liner is connected to one side of the first copper electrode, and the other side of the first copper electrode is connected to the first indium sheet.

[0010] The sample pressurization module is connected to one side of the electrode fixing plate, the other side of the electrode fixing plate is connected to one side of the second insulating liner, the other side of the second insulating liner is connected to one side of the second copper electrode, and the other side of the second copper electrode is connected to the second indium sheet.

[0011] The first indium sheet, the second indium sheet, the sample holder, and the probe module form a space to accommodate the sample to be tested. The first indium sheet and the second indium sheet are respectively located at the end face of the sample to be tested, and the sample holder and the probe module are respectively located at the crystal plane of the sample to be tested.

[0012] The sample pressurization module is used to move the electrode fixing plate horizontally to adjust the position of the second indium sheet and the end face of the sample to be tested. The slide module is used to move the probe module vertically to adjust the distance between the wedge probe and the crystal surface of the sample to be tested.

[0013] As a preferred technical solution, the slide module includes a height adjustment mechanism and a self-locking handwheel. The height adjustment mechanism is provided with a screw-slider mechanism. The self-locking handwheel is connected to the screw-slider mechanism. The screw-slider mechanism is fixedly connected to the probe module. The self-locking handwheel is used to drive the screw-slider mechanism to slide in the vertical direction.

[0014] As a preferred technical solution, the probe module further includes a spring fixing bracket, a spring plate, a fixing bracket, a first insulating pad, a second insulating pad, a probe adjusting bolt, a spring plate insulating sheet, and a fixing pad;

[0015] The slide module is connected to a fixed bracket, which is connected to a spring fixing bracket. A first insulating gasket, a spring plate, and a second insulating gasket are sequentially provided between the spring fixing bracket and the fixing gasket. The spring fixing bracket, the fixing gasket, and one end of the spring plate are fixedly connected, and the other end of the spring plate is fixedly connected to a wedge-shaped probe.

[0016] The probe pressure adjusting bolt passes through the spring fixing bracket, and the end of the probe pressure adjusting bolt contacts the spring sheet through the spring sheet insulation sheet, which is used to change the deformation pressure of the spring sheet and adjust the contact pressure between the wedge probe and the sample to be tested.

[0017] As a preferred technical solution, the wedge probe is provided with a fixing seat and a wedge-shaped part, the fixing seat and the wedge-shaped part are integrally formed, the fixing seat is connected to the spring plate, the wedge-shaped part extends in the vertical direction, one end of the wedge-shaped part is connected to the fixing seat, and the other end of the wedge-shaped part is provided with a tip, which is formed by the intersection of two cut surfaces, and the included angle between the two cut surfaces is an acute angle.

[0018] As a preferred technical solution, the tip is provided with a flattened section, which is formed by flattening the intersection of two cut surfaces.

[0019] As a preferred technical solution, the intersection line of the tip of the wedge probe is perpendicular to the central axis of the sample to be tested.

[0020] As a preferred technical solution, the wedge-shaped probes are arranged at equal intervals along the same straight line.

[0021] As a preferred technical solution, the sample pressurization module includes: a pressure regulating screw, a limiting plate, a fixing frame, a bearing, a guide column, a fixing bolt, and a pressure regulating handwheel;

[0022] The bearing is connected to the electrode fixing plate, one end of the voltage adjusting screw is connected to the bearing, and the other end of the voltage adjusting screw is connected to the voltage adjusting handwheel;

[0023] The fixing frame is mounted on the mounting base plate, one end of the guide post is fixedly connected to the electrode fixing plate, and the other end of the guide post passes through the fixing frame;

[0024] The fixing frame is provided with a fixing frame base, the mounting base plate is provided with a through groove, the fixing bolt passes through the fixing frame base, the fixing bolt passes through the through groove and is movably connected to the limiting plate, and there is a movable gap between the fixing bolt and the through groove.

[0025] As a preferred technical solution, the sample pressurization module includes: a limiting plate, a fixing frame, a guide post, and fixing bolts;

[0026] The fixing frame is mounted on the mounting base plate. One end of the guide post is fixedly connected to the electrode fixing plate, and the other end of the guide post is fixedly connected to the fixing frame. A spring is sleeved on the guide post.

[0027] The fixing frame is provided with a fixing frame base, the mounting base plate is provided with a through groove, the fixing bolt passes through the fixing frame base, the fixing bolt passes through the through groove and is movably connected to the limiting plate, and there is a movable gap between the fixing bolt and the through groove.

[0028] As a preferred technical solution, the sample holder is provided with a dovetail groove, which is used to fix the sample position.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] (1) The present invention sets a wedge probe above the longitudinal measurement channel of the single crystal. The wedge probe is driven to contact the single crystal by the sliding stage module. Each probe has a pressure adjustable spring plate to pressurize the probe, ensuring good contact between the probe and the sample at low temperature. The potential difference between two adjacent probes can be read in the order from beginning to end of the single crystal, thereby calculating the resistivity of each part. This achieves the goal of obtaining the resistivity distribution of the entire high-purity germanium single crystal quickly without the need for slicing and sample preparation.

[0031] (2) The present invention uses a sample pressurization module to press the indium sheet tightly against the end face of the single crystal, forming a good ohmic contact. Without the need for slicing, the whole single crystal with cut ends is placed directly into the space for the sample to be tested formed between the first indium sheet, the second indium sheet, the sample holder and the probe module. The single crystal can still form a stable measurement current even at -196 degrees Celsius. At the same time, the process of welding electrodes and leads on the sample is eliminated, making the overall measurement more accurate, more convenient and more widely applicable. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the semiconductor resistivity measuring device at liquid nitrogen temperature in Example 1 of this embodiment;

[0033] Figure 2 A schematic diagram of the positioning fixture for the semiconductor resistivity measuring device at liquid nitrogen temperature in this embodiment 1;

[0034] Figure 3 A side view of the structure of the positioning fixture for the semiconductor resistivity measuring device at liquid nitrogen temperature in this embodiment 1;

[0035] Figure 4 This is a schematic diagram of the sample holder structure in Example 1 of this embodiment;

[0036] Figure 5 This is a schematic diagram of the probe module in Embodiment 1.

[0037] Figure 6 This is a side view of the probe module in Embodiment 1.

[0038] Figure 7 This is a schematic diagram of the wedge-shaped probe in Embodiment 1.

[0039] Figure 8(a) is a schematic diagram of the wedge probe with a flattened section in this embodiment 1;

[0040] Figure 8(b) is an enlarged view of point A in Figure 8(a);

[0041] Figure 9 This is a schematic diagram of the structure under the test state of the wedge probe in Embodiment 1;

[0042] Figure 10This is a schematic diagram of the structure of the sample pressurization module in Embodiment 1.

[0043] Figure 11 This is an exploded view of the structure of the pressurized active module of sample 1 in this embodiment;

[0044] Figure 12 This is a schematic diagram of the structure of the sample pressurization module in Example 2 of this embodiment.

[0045] Among them, 1-mounting base plate, 2-sample holder, 3-germanium sample, 4-foot, 5-wedge probe, 6-probe pressure adjusting bolt, 7-slide table module, 8-fixed vertical plate, 9-first indium sheet, 10-second indium sheet, 11-first copper electrode, 12-second copper electrode, 13-first insulating liner, 14-second insulating liner, 15-sample pressurization movable module, 16-spring fixing bracket, 17-spring plate, 18-fixed bracket 191-First insulating gasket, 192-Second insulating gasket, 20-Spring insulating sheet, 21-Probe fixing screw, 22-Fixing gasket; 23-Adjusting screw, 24-Limiting plate, 25-Fixing bracket, 26-Bearing, 27-Guide post, 28-Fixing bolt, 29-Adjusting handwheel, 30-Electrode fixing plate, 31-Positioning clamp, 32-Fixing seat, 33-Wedge-shaped part, 34-Screw hole, 35-Flattened part. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0047] Example 1

[0048] like Figure 1 , Figure 2 , Figure 3 As shown, this embodiment provides a semiconductor resistivity measuring device at liquid nitrogen temperature, specifically including: a mounting base plate 1, a sample holder 2, a foot 4, a probe module, a slide module 7, a fixed vertical plate 8, a first indium sheet 9, a second indium sheet 10, a first copper electrode 11, a second copper electrode 12, a first insulating liner 13, a second insulating liner 14, and a sample pressurization movable module 15;

[0049] Among them, the sample holder 2, the sliding table module 7, the fixed vertical plate 8 and the sample pressurizing movable module 15 are all set on the mounting base plate 1 and are fixedly connected to the mounting base plate 1 respectively. The bottom of the mounting base plate 1 is connected to the foot 4. In this embodiment, multiple foot 4 can be set, and 4-8 can be selected.

[0050] The sample holder 2 is used to support the germanium sample 3. The probe module is equipped with multiple wedge-shaped probes, which are in contact with the crystal surface of the germanium sample 3. Preferably, there are fifteen wedge-shaped probes.

[0051] The slide module 7 is equipped with a height adjustment mechanism, which is movably connected to the main body of the slide module and fixedly connected to the probe module. It is used to drive the probe module to slide in the vertical direction. Since the diameter of germanium single crystal may vary in the range of 40mm-80mm, the distance between the probe module and the crystal surface of the germanium sample can be adjusted by adjusting the height adjustment mechanism to better match the size of the germanium single crystal and make it more widely applicable.

[0052] In this embodiment, the slide module is equipped with a handwheel with a self-locking structure. The height adjustment mechanism can use the handwheel to drive the screw slider mechanism to adjust the height. After adjusting the height, the handwheel is locked to lock the current height. The slide module 7 uses an all-metal slide, which can withstand the switching between low temperature and room temperature without deformation and can work normally at low temperature.

[0053] In this embodiment, the fixed vertical plate 8 and the sample pressurization active module 15 are arranged opposite to each other on the mounting base plate 1, respectively positioned near the two end faces of the germanium sample 3.

[0054] In this embodiment, the inner side of the fixed vertical plate 8 (the side closest to the end face of the germanium sample) is connected to one side of the first insulating liner 13, the other side of the first insulating liner 13 is connected to one side of the first copper electrode 11, and the other side of the first copper electrode 11 is connected to the first indium sheet 9. In this embodiment, the indium sheet can be fixed to the first copper electrode by countersunk screws distributed around the periphery, and the corresponding position on the first copper electrode has a threaded hole.

[0055] In this embodiment, the sample pressurization module 15 is connected to one side of the electrode fixing plate 30, the other side of the electrode fixing plate 30 is connected to one side of the second insulating liner 14, the other side of the second insulating liner 14 is connected to one side of the second copper electrode 12, and the other side of the second copper electrode 12 is connected to the second indium sheet 10. In this embodiment, the first indium sheet 9 and the second indium sheet 10 are respectively located at the two end faces of the germanium sample.

[0056] In this embodiment, the sample pressurization module 15 is used to drive the electrode fixing plate to move in the horizontal direction. The first indium sheet 9, the second indium sheet 10, the sample holder 2 and the probe module form a space for receiving the germanium sample 3. By adjusting the slide module 7, the distance between the probe module and the crystal surface of the germanium sample is changed so that the probe module contacts the crystal surface of the germanium sample. By adjusting the sample pressurization module, the first indium sheet 9 and the second indium sheet 10 contact the two end faces of the germanium sample respectively.

[0057] In this embodiment, the first and second indium sheets are made of high-purity indium, which remains flexible even at a low temperature of -196 degrees Celsius. Indium is a good conductor, and when the sample surface is uneven, it can ensure full contact between the sample and the copper electrode, resulting in better measurement results.

[0058] Combination Figure 2 and Figure 3 As shown, the first copper electrode and the second copper electrode are connected to an external constant current source via wires, and the spring sheet is connected to a voltage source via wires. The first copper electrode and the second copper electrode are both made of high-quality brass. Copper has good performance and conductivity at low temperatures, which can distribute the test voltage evenly, so that the current flowing through the sample is evenly distributed, resulting in good measurement effect.

[0059] This embodiment also includes a positioning fixture 31, which is wire-cut and matches the shape of the chisel probe. The gap is within 0.005mm. The positioning fixture 31 restricts the two probes to be on a straight line, and the distance between them is within 10mm ± 0.01mm.

[0060] like Figure 4 As shown, the sample holder 2 is provided with a dovetail groove for fixing the sample position. In this embodiment, the sample holder is made of polytetrafluoroethylene, which can withstand temperatures from -196 degrees Celsius to room temperature of 40 degrees Celsius.

[0061] like Figure 5 , Figure 6 As shown, the probe module specifically includes: a spring fixing bracket 16, a spring plate 17, a fixing bracket 18, a wedge-shaped probe 5, a first insulating pad 191, a second insulating pad 192, a probe adjusting bolt 6, a spring plate insulating sheet 20, a probe fixing screw 21, and a fixing pad 22.

[0062] The slide module 7 is connected to the fixed bracket 18 with screws. The slide module 7 is provided with fixing screw holes and is fixed to the fixed bracket 18 in the probe module with bolts. The fixed bracket 18 is fixedly connected to the spring fixed bracket 16 by fastening screws. The spring fixed bracket is used to support the spring plate. A first insulating gasket 191, a spring plate 17, and a second insulating gasket 192 are provided between the spring fixed bracket 16 and the fixed gasket 22 in sequence. The spring plate insulating sheet 20 is adhered to the spring plate 17.

[0063] In this embodiment, both the first insulating pad and the second insulating pad are made of polytetrafluoroethylene (PTFE), which is resistant to low temperatures. Since the entire slide is made of metal and the test signal is a voltage signal, the spring plate 17 and the spring fixing bracket 16 need to be electrically insulated with insulating material. Therefore, the first insulating pad and the second insulating pad are provided for electrical insulation.

[0064] In this embodiment, the fixing washer is made of aluminum alloy. Because the spring sheet 17 deforms and generates elasticity during testing, and the first and second insulating washers are made of soft materials, they cannot provide sufficient strength. Therefore, a metal fixing washer must be added. The fixing washer is secured to the spring fixing bracket with screws. The screws pass through the fixing holes between the copper spring sheet, the first insulating washer, and the second insulating washer, and are encased in PTFE tubing for electrical insulation.

[0065] The spring fixing bracket 16 is provided with a fastening screw and a probe adjusting bolt 6. The fastening screw is used to fix one end of the spring plate 17 to the fixing bracket 18, and the other end of the spring plate 17 is connected to the wedge probe 5 through the fixing screw 21.

[0066] The probe pressure adjusting bolt 6 contacts the spring plate 17 through the spring plate insulating sheet 20. Adjusting the contact pressure between the probe pressure adjusting bolt and the spring plate can press down the end of the spring plate connected to the wedge probe, thereby changing the contact pressure between the wedge probe and the sample.

[0067] In this embodiment, the front end (the bottom of the bolt) of the probe pressure adjusting bolt 6 presses against the polytetrafluoroethylene sheet fixed by the copper spring sheet 17. The polytetrafluoroethylene sheet (referring to the spring sheet insulating sheet 20) can be adjusted by adjusting the length of the pressing bolt to press down the spring sheet and change the pressure in contact with the sample.

[0068] In this embodiment, the spring sheet is made of beryllium bronze and has a relatively long length, which allows it to contact the crystal surface even when the single crystal diameter varies greatly. It is also equipped with an independent pressure structure, and the pressure can be adjusted by adjusting the probe pressure adjustment bolt.

[0069] In this embodiment, instead of the usual cone, a wedge-shaped probe is used. The wedge-shaped probe can have a larger contact area on the equilateral surface of the crystal and is fixed by a fixing screw and a spring sheet.

[0070] like Figure 7 As shown, the wedge probe 5 includes a fixing base 32 and a wedge portion 33. The fixing base 32 and the wedge portion 33 are integrally formed. The fixing base 32 is provided with a screw hole 34. The screw hole 34 is fixedly connected to the spring plate 17 by a screw. The wedge portion 33 extends in the vertical direction. One end of the wedge portion is connected to the fixing base, and the other end of the wedge portion is provided with a tip. The tip is formed by the intersection of two cut surfaces. The included angle between the two cut surfaces is an acute angle, preferably a 60-degree included angle.

[0071] As shown in Figures 8(a) and 8(b), the tip is also provided with a flattened part 35, which is formed by flattening the intersection of the two cut surfaces. That is, a small obtuse angle is made at the tip to ensure full contact with the sample surface.

[0072] like Figure 9As shown, the intersection line of the tip of the wedge probe is perpendicular to the central axis of the sample to be tested. The sample has unequal diameters in the direction of the dotted line. At this time, adjust the probe pressure adjustment screw to press down the wedge probe. Since the bottom of the wedge probe is a long wedge shape, the lower end face of the wedge probe can still be tangent to the circular surface of the sample with unequal diameters and make full contact.

[0073] In this embodiment, the probe fixing screw is used to fix the wedge probe and the spring plate. Before fixing the spring plate, the probe position is adjusted to the defined position of the positioning fixture, and the central axis of the groove in the positioning fixture where the probe is placed is perpendicular to the central axis of the electrode. The positioning fixture is cut with precision wire cutting to create a groove that can only accommodate the wedge probe. The groove is perpendicular to the central axis of the copper electrodes at both ends. After the wedge probe is adjusted to enter the groove, the fixing screw is tightened, thus ensuring that the wedge probe is perpendicular to the central axis of the single crystal.

[0074] like Figure 10 , Figure 11 As shown, the sample pressurization module 15 includes: a pressure regulating screw 23, a limiting plate 24, a fixing frame 25, a bearing 26, a guide post 27, a fixing bolt 28, and a pressure regulating handwheel 29.

[0075] The mounting bracket 25 is mounted on the mounting base plate 1. One end of the guide post 27 is fixedly connected to the electrode fixing plate 30. The guide post 27 is fixed in position on the side of the electrode fixing plate 30 with screws. The other end of the guide post 27 passes through the round hole provided on the mounting bracket 25, guiding the electrode fixing plate to move left and right in the horizontal direction. The bearing 26 is fixed to the electrode fixing plate 30 with screws. The bearing 26 has a central inner hole. The pressure adjusting screw 23 passes through the inner hole of the bearing and is fixedly connected by a limiter. The other side of the electrode fixing plate 30 is connected to the side of the second insulating liner 14 with screws. The other side of the second insulating liner 14 is fitted with a fixing nut and connected to the side of the second copper electrode 12 with screws. The other side of the second copper electrode 12 is connected to the second indium sheet 10 with countersunk screws.

[0076] The mounting bracket 25 is provided with a pressure adjusting screw hole and a fixing bolt hole. The pressure adjusting screw 23 passes through the pressure adjusting screw hole, one end of which is connected to the pressure adjusting handwheel 29, and the other end of which is connected to the bearing 26. The fixing bolt 28 is connected to the limiting plate 24 through the fixing bolt hole. The limiting plate is fixedly connected to the mounting base plate 1 through the fixing bolt.

[0077] In this embodiment, the total length of the sample is in the range of 40-160mm. The sample pressurization movable module can be adjusted to the left and right position in the horizontal direction as needed. The fixing frame and the limiting plate are fixed to the mounting base plate with bolts. The mounting base plate is provided with two through slots for bolt sliding. Loosen the bolts, and the sample pressurization movable module can be moved to the left and right to a suitable position. Then tighten the two bolts to fix the sample pressurization movable module for pressure adjustment.

[0078] When the indium sheet is not parallel to the sample surface, adjusting the slots of the two bolts fixed in the mounting base plate can adjust the sample pressure moving module to make the indium sheet parallel to the sample surface.

[0079] In this embodiment, when the sample length varies greatly, the sample pressurization module can be adjusted to a suitable position, and the handwheel can be adjusted to ensure that the indium sheet on the copper electrode is in full contact with the sample surface. Adjusting the handwheel position also allows for adjustment of the pressure applied to the circular surfaces at both ends of the sample. When the two end faces of the germanium single crystal sample are slightly non-parallel, the fixing bolts can be loosened, and the fixing frame can be slightly rotated to make the movable copper electrode as parallel as possible to the single crystal end face.

[0080] In this embodiment, the bearing is treated with a special all-metal process (such as surface nitriding), which can withstand the switching between low temperature and room temperature without deformation and can work normally at low temperature.

[0081] In this embodiment, the materials and moving parts of the semiconductor resistivity measuring device at liquid nitrogen temperature can withstand low temperatures, enabling it to operate from -196 degrees Celsius in liquid nitrogen to 40 degrees Celsius in room temperature.

[0082] In this embodiment, the semiconductor resistivity measuring device at liquid nitrogen temperature operates in a cryogenic chamber at -196 degrees Celsius. The first copper electrode, the second copper electrode, and the 16 wedge-shaped probes are all connected to a constant current source and a digital voltage tester outside the cryogenic chamber via multi-core cryogenic cables (through wire holes). The current from the constant current source enters the germanium single crystal being measured through the first copper electrode and the first indium plate. The current flows out through the single crystal from the second indium plate and the second copper electrode, returning to the constant current source. Of course, the current can also flow in the reverse direction.

[0083] The 15 wedge-shaped probes in this embodiment can be divided into 7 or more pairs. Each adjacent probe can form a pair. When the probes press against the single crystal, a pair of probes (i) can be connected to a digital voltmeter in sequence via a cable to measure the potential difference V. i The single-crystal resistivity ρ beneath this pair of probes i The resistivity can be obtained using the two-probe method:

[0084]

[0085] Where S is the cross-sectional area of ​​the germanium single crystal, and d is the distance between the two probes (1 cm).

[0086] The mobility of germanium single crystal at 77°K is known to be: μ 电子 =3.619×10 4 cm 2 / v·s;

[0087] μ 空穴 =4.223×10 4 cm2 / v·s;

[0088] Thus, the carrier concentration can be obtained: (hole concentration);

[0089] Type N: (Electron concentration)

[0090] e is the electron charge = 1.6021892 × 10 -19 coulomb

[0091] Resistivity and carrier concentration directly reflect the purity of germanium, and are therefore important quality parameters for germanium single crystals.

[0092] Example 2

[0093] Except for the following technical features, the remaining technical features of this embodiment are the same as those of Embodiment 1 above. This embodiment provides another structure for a sample pressurization active module, such as... Figure 12 As shown, the sample pressurization module specifically includes: a limiting plate 24, a fixing frame 25, a guide post 27, and a fixing bolt 28. The fixing frame 25 is mounted on the mounting base plate 1. One end of the guide post 27 is fixedly connected to the electrode fixing plate 30, and the other end of the guide post 27 is fixedly connected to the fixing frame. A spring is provided on the guide post 27, with one end of the spring close to the electrode fixing plate and the other end of the spring close to the fixing frame.

[0094] The fixed frame 25 is provided with a fixed frame base, the mounting base plate 1 is provided with a through groove, the fixing bolt 28 passes through the fixed frame base, the fixing bolt passes through the through groove and is movably connected to the limiting plate 24, and there is a movable gap between the fixing bolt 28 and the through groove.

[0095] In this embodiment, pressure is applied to the spring by the fixing frame, and the guide column guides the movement of the electrode fixing plate, thereby causing the second copper electrode to move left and right in the horizontal direction.

[0096] In this embodiment, the spring can be a beryllium copper spring.

[0097] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A semiconductor resistivity measuring device at liquid nitrogen temperature, characterized in that, include: Mounting base plate, sample holder, probe module, slide module, fixed vertical plate, first indium sheet, second indium sheet, first copper electrode, second copper electrode, first insulating liner, second insulating liner and sample pressurization movable module; The probe module is equipped with multiple wedge-shaped probes, which are used to contact the crystal surface of the sample to be tested; The sample holder, the fixed vertical plate, and the sample pressurization movable module are respectively connected to the mounting base plate, and the slide module is connected to the probe module; One side of the fixed vertical plate is connected to one side of the first insulating liner, the other side of the first insulating liner is connected to one side of the first copper electrode, and the other side of the first copper electrode is connected to the first indium sheet. The sample pressurization module is connected to one side of the electrode fixing plate, the other side of the electrode fixing plate is connected to one side of the second insulating liner, the other side of the second insulating liner is connected to one side of the second copper electrode, and the other side of the second copper electrode is connected to the second indium sheet. The first indium sheet, the second indium sheet, the sample holder, and the probe module form a space to accommodate the sample to be tested. The first indium sheet and the second indium sheet are respectively located at the end face of the sample to be tested, and the sample holder and the probe module are respectively located at the crystal plane of the sample to be tested. The sample pressurization module is used to move the electrode fixing plate horizontally to adjust the position of the second indium sheet and the end face of the sample to be tested. The slide module is used to move the probe module vertically to adjust the distance between the wedge probe and the crystal surface of the sample to be tested.

2. The semiconductor resistivity measuring device at liquid nitrogen temperature according to claim 1, characterized in that, The slide module includes a height adjustment mechanism and a self-locking handwheel. The height adjustment mechanism is equipped with a screw-slider mechanism. The self-locking handwheel is connected to the screw-slider mechanism. The screw-slider mechanism is fixedly connected to the probe module. The self-locking handwheel is used to drive the screw-slider mechanism to slide in the vertical direction.

3. The semiconductor resistivity measuring device at liquid nitrogen temperature according to claim 1, characterized in that, The probe module also includes a spring fixing bracket, a spring plate, a fixing bracket, a first insulating pad, a second insulating pad, a probe adjusting bolt, a spring plate insulating sheet, and a fixing pad; The slide module is connected to a fixed bracket, which is connected to a spring fixing bracket. A first insulating gasket, a spring plate, and a second insulating gasket are sequentially provided between the spring fixing bracket and the fixing gasket. The spring fixing bracket, the fixing gasket, and one end of the spring plate are fixedly connected, and the other end of the spring plate is fixedly connected to a wedge-shaped probe. The probe pressure adjusting bolt passes through the spring fixing bracket, and the end of the probe pressure adjusting bolt contacts the spring sheet through the spring sheet insulation sheet, which is used to change the deformation pressure of the spring sheet and adjust the contact pressure between the wedge probe and the sample to be tested.

4. The semiconductor resistivity measuring device at liquid nitrogen temperature according to claim 1, characterized in that, The wedge probe has a fixed seat and a wedge-shaped part, which are integrally formed. The fixed seat is connected to a spring plate. The wedge-shaped part extends vertically. One end of the wedge-shaped part is connected to the fixed seat. The other end of the wedge-shaped part has a pointed tip, which is formed by the intersection of two cut surfaces. The included angle between the two cut surfaces is an acute angle.

5. The semiconductor resistivity measuring device at liquid nitrogen temperature according to claim 4, characterized in that, The tip is provided with a flat section, which is formed by flattening the intersection of two cut surfaces.

6. The semiconductor resistivity measuring device at liquid nitrogen temperature according to claim 1 or 5, characterized in that, The intersection line of the tip of the wedge probe is perpendicular to the central axis of the sample to be tested.

7. The semiconductor resistivity measuring device at liquid nitrogen temperature according to claim 1, characterized in that, The wedge-shaped probes are arranged at equal intervals along the same straight line.

8. The semiconductor resistivity measuring device at liquid nitrogen temperature according to claim 1, characterized in that, The sample pressurization module includes: a pressure regulating screw, a limiting plate, a fixing frame, a bearing, a guide column, fixing bolts, and a pressure regulating handwheel; The bearing is connected to the electrode fixing plate, one end of the voltage adjusting screw is connected to the bearing, and the other end of the voltage adjusting screw is connected to the voltage adjusting handwheel; The fixing frame is mounted on the mounting base plate, one end of the guide post is fixedly connected to the electrode fixing plate, and the other end of the guide post passes through the fixing frame; The fixing frame is provided with a fixing frame base, the mounting base plate is provided with a through groove, the fixing bolt passes through the fixing frame base, the fixing bolt passes through the through groove and is movably connected to the limiting plate, and there is a movable gap between the fixing bolt and the through groove.

9. The semiconductor resistivity measuring device at liquid nitrogen temperature according to claim 1, characterized in that, The sample pressurization module includes: a limiting plate, a fixing frame, a guide post, and fixing bolts; The fixing frame is mounted on the mounting base plate. One end of the guide post is fixedly connected to the electrode fixing plate, and the other end of the guide post is fixedly connected to the fixing frame. A spring is sleeved on the guide post. The fixing frame is provided with a fixing frame base, the mounting base plate is provided with a through groove, the fixing bolt passes through the fixing frame base, the fixing bolt passes through the through groove and is movably connected to the limiting plate, and there is a movable gap between the fixing bolt and the through groove.

10. The semiconductor resistivity measuring device at liquid nitrogen temperature according to claim 1, characterized in that, The sample holder is provided with a dovetail groove, which is used to fix the sample position.

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