Device for measuring resistivity of semiconductive compound semiconductor

Abstract

The utility model discloses a device for measuring the resistivity of a semi-conductive compound semiconductor. The device comprises a four-probe probe, a voltage measuring circuit, a current measuring circuit, a barrier-eliminating voltage generating circuit capable of adjusting the voltage value of a pulse signal, a constant current source, a single-chip microcomputer, and a man-machine interaction device used for setting the pulse width. A first probe and a fourth probe of the four-probe probe are connected with a current measuring circuit, and a second probe and a third probe are connected with a voltage measuring circuit; the current measuring circuit and the voltage measuring circuit are respectively connected with the single chip microcomputer, the single chip microcomputer is respectively connected with the constant current source and the man-machine interaction equipment, and the constant current source is connected with the four-probe probe; the single-chip microcomputer is connected with the input end of the barrier-eliminating voltage generating circuit, and the barrier-eliminating voltage generating circuit outputs pulse signals with positive and negative polarities between a second probe and a third probe of the four-probe probe. According to the utility model, the potential barrier formed when the probe is contacted with the sample to be measured can be eliminated, and the distributed measurement of the resistivity of the semi-conductive semiconductor material is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of resistivity measurement, in particular to a measuring device for the resistivity of a semi-conductive compound semiconductor. Background Art

[0002] Semi-conductive compound semiconductors are wide-bandgap semiconductors developed after the first-generation semiconductor material Si (second-generation semiconductor materials such as GaAs and InP, and third-generation semiconductor materials such as SiC and GaN). They have characteristics such as wide bandgap, high critical breakdown electric field, high thermal conductivity, high carrier saturation concentration, strong radiation resistance, and small dielectric constant. They are suitable for preparing high-temperature, high-frequency, high-power electronic devices and excellent microwave and optoelectronic devices. Such wide-bandgap semiconductors are also called compound semiconductors.

[0003] For the research of any semiconductor material, resistivity is a very important basis and an important basic electrical parameter that must be measured during the R & D and production processes. The resistivity distribution of a whole (ingot) or whole semiconductor crystal material can truly and completely reflect the quality of the material.

[0004] The currently commonly used semiconductor material testing methods mainly include the Hall method and the Van der Pauw method. Both of these methods require cutting the sample to obtain a sample piece with a specific shape and preparing ohmic contacts, resulting in a long measurement cycle. If only the resistivity is measured, the eddy current method is generally used at present. Although it avoids the trouble of sample preparation, it can only measure sample pieces with a certain thickness, and the thickness of the measured compound semiconductor sample piece must be the same as that of the standard sample piece. A bigger problem is that the eddy current method must use a set of standard pieces with known resistivity to calibrate the instrument. However, for the currently commonly used resistivity testing methods, such as the DC four-probe method widely used in the resistivity measurement of the first-generation semiconductors (silicon and germanium), it is still unable to effectively measure semi-conductive GaAs, SiC, and GaN. This is because when the probe contacts these materials, a potential barrier is formed, resulting in an extremely high contact resistance, so that a digital meter with an input impedance of 1 MΩ cannot stably measure the voltage signal between the second and third probes. Therefore, the resistivity of the sample cannot be measured, and the standard sample piece can only be replaced by a silicon wafer, and the accuracy of this replacement is uncertain, and its reliability has not been experimentally verified.

[0005] Therefore, it is necessary to provide a non-destructive semi-conductive compound semiconductor resistivity mapping technology with no restrictions on the sample piece thickness. Summary of the Invention

[0006] In order to overcome the defects and deficiencies of the existing technology, the present utility model provides a measuring device for the resistivity of a semi-conductive compound semiconductor. The measuring device applies positive and negative polarity pulse signals between the second probe and the third probe of a four-probe probe in contact with a sample to be measured on a sample stage based on a barrier potential elimination voltage generation circuit, eliminates the barrier potential formed when the probe contacts the sample to be measured, thereby greatly reducing the contact resistance, enabling the accurate measurement of the resistivity of the semi-conductive compound by the four-probe method, realizing the distributed measurement of the resistivity of the semi-conductive semiconductor material, and accurately reflecting the overall performance of the material.

[0007] In order to achieve the above object, the present utility model adopts the following technical solutions:

[0008] The present invention provides a measuring device for the resistivity of a semi-conductive compound semiconductor, comprising: a four-probe probe, a voltage measurement circuit, a current measurement circuit, a barrier potential elimination voltage generation circuit, a constant current source, a single-chip microcomputer, and a human-computer interaction device;

[0009] The four-probe probe is respectively provided with a first probe, a second probe, a third probe, and a fourth probe. The first probe and the fourth probe are connected to the current measurement circuit, and the second probe and the third probe are connected to the voltage measurement circuit;

[0010] The current measurement circuit and the voltage measurement circuit are respectively connected to the single-chip microcomputer. The single-chip microcomputer is respectively connected to the constant current source and the human-computer interaction device. The constant current source is connected to the four-probe probe;

[0011] The single-chip microcomputer is connected to the input end of the barrier potential elimination voltage generation circuit. The output end of the barrier potential elimination voltage generation circuit is connected to the second probe and the third probe, and outputs positive and negative polarity pulse signals between the second probe and the third probe of the four-probe probe to eliminate the barrier potential formed when the probe contacts the sample to be measured;

[0012] The barrier potential elimination voltage generation circuit is provided with a barrier potential elimination voltage knob for adjusting the voltage value of the pulse signal;

[0013] The human-computer interaction device is used to set the pulse width, transmit it to the barrier potential elimination voltage generation circuit through the single-chip microcomputer, and calculate the resistivity of the sample to be measured after eliminating the barrier potential;

[0014] The constant current source is used to output a constant current.

[0015] As a preferred technical solution, the four-probe probe is in pressing contact with the position to be measured on the surface of the sample to be measured through a motion control guide rail.

[0016] As a preferred technical solution, the four-probe probe adopts a straight row four-probe probe.

[0017] As a preferred technical solution, the barrier voltage generating circuit is provided with a control circuit for positive and negative polarity pulse signals, including: a first relay K8, a second relay K9, a capacitor, a power supply VCC terminal, and a ground terminal;

[0018] The first pair of normally open contacts of the first relay K8 are respectively connected to the second probe of the four-probe probe and the first common terminal of the second relay K9. The normally closed contact and the normally open contact corresponding to the first common terminal are respectively connected to the power supply VCC terminal and the ground terminal;

[0019] The second pair of normally open contacts of the first relay K8 are respectively connected to the third probe of the four-probe probe and the second common terminal of the second relay K9. The normally closed contact and the normally open contact corresponding to the second common terminal are respectively connected to the ground terminal and the power supply VCC terminal;

[0020] Both ends of the capacitor are respectively connected to the second probe and the third probe of the four-probe probe;

[0021] The voltage of the power supply VCC terminal is adjusted by a barrier voltage knob. The single-chip microcomputer is used to control the first pair of normally open contacts and the second pair of normally open contacts of the first relay K8 to close, and output a positive polarity pulse signal. The single-chip microcomputer controls the first pair of normally open contacts and the second pair of normally open contacts of the first relay K8, and the normally open contacts corresponding to the first common terminal and the second common terminal of the second relay K9 to close, and output a negative polarity pulse signal.

[0022] As a preferred technical solution, the barrier voltage generating circuit is further provided with a relay K8 control circuit, including: a first resistor R55, a first triode VT14, and a first diode VD31;

[0023] One end of the first resistor R55 is connected to the second output IO port of the single-chip microcomputer. The other end of the first resistor R55 is connected to the base of the first triode VT14. The emitter of the first triode VT14 is grounded. The collector of the first triode VT14 is connected to one end of the coil of the first relay K8. The other end of the coil of the first relay K8 is connected to the positive pole of the power supply. The positive pole of the first diode VD31 is connected to one end of the coil of the first relay K8. The negative pole of the first diode VD31 is connected to the other end of the coil of the first relay K8.

[0024] As a preferred technical solution, the barrier voltage generating circuit is further provided with a relay K9 control circuit, including: a second resistor R58, a second triode VT15, and a second diode VD34;

[0025] One end of the second resistor R58 is connected to the first output IO port, the other end of the second resistor R58 is connected to the base of the second triode VT15, the emitter of the second triode VT15 is grounded, the collector of the second triode VT15 is connected to one end of the coil of the second relay K9, the other end of the coil of the second relay K9 is connected to the positive pole of the power supply, the positive pole of the second diode VD34 is connected to one end of the coil of the second relay K9, and the negative pole of the second diode VD34 is connected to the other end of the coil of the second relay K9.

[0026] As a preferred technical solution, the single-chip microcomputer is further provided with a third output IO port, the third output IO port is connected to one end of the constant current source switch, and the other end of the constant current source switch is connected to the positive pole of the power supply.

[0027] As a preferred technical solution, the constant current source is provided with a current selection gear, and the single-chip microcomputer is connected to the current selection gear of the constant current source.

[0028] As a preferred technical solution, the current selection gears include 1-10 mA, 10-100 mA, and 100-500 mA gears.

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

[0030] The present invention measures the resistivity of a semi-conductive semiconductor based on the principle of eliminating contact barriers, without the need to cut the sample piece, belonging to non-destructive measurement. The output end of the barrier elimination voltage generation circuit outputs positive and negative polarity pulse signals between the second probe and the third probe of the four-probe probe. The amplitude and width of the pulse signals are controllable, eliminating the barriers formed when the probe contacts the sample to be measured, thereby greatly reducing the contact resistance, enabling the resistivity of the semi-conductive compound to be accurately measured by the four-probe method, calculating the sample resistivity according to the voltage changes of each measurement point collected by the four-probe probe, realizing the distributed measurement of the resistivity of the semi-conductive semiconductor material, and accurately reflecting the overall performance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structure of the measuring device for the resistivity of the semi-conductive compound semiconductor of the present invention;

[0032] Figure 2 It is a schematic diagram of the structure of the four-probe probe of the present invention;

[0033] Figure 3 It is a schematic diagram of the pulse signal control circuit structure of the barrier elimination voltage generation circuit of the present invention;

[0034] Figure 4 It is a schematic diagram of the relay control circuit structure of the barrier elimination voltage generation circuit of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] In order to make the objectives, technical solutions and advantages of the present utility model clearer and more understandable, the present utility model 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 only used to explain the present utility model and are not used to limit the present utility model.

[0036] Embodiment

[0037] As Figure 1 shown, this embodiment provides a measuring device for the resistivity of a semi-conductive compound semiconductor, including: a four-probe probe, a voltage measurement circuit, a current measurement circuit, a barrier voltage generation circuit, a constant current source, a single-chip microcomputer, and a human-computer interaction device;

[0038] As Figure 2 shown, the four-probe probe adopts a straight-row four-probe probe. The four-probe probe is in press-contact with the measured position on the surface of the sample to be measured through a motion control guide rail. The four-probe probe is respectively provided with a first probe, a second probe, a third probe, and a fourth probe. The first probe and the fourth probe are connected to the current measurement circuit through a shielded cable. The current measurement circuit detects the current value flowing between the first probe and the fourth probe by detecting the voltage of a standard resistor in the detection circuit. The second probe and the third probe are connected to the voltage measurement circuit through a shielded cable. The voltage measurement circuit measures the potential difference between the second probe and the third probe and sends it to the single-chip microcomputer;

[0039] In this embodiment, the sample to be measured can adopt a general sample or a standard sample, such as a single crystal ingot;

[0040] In this embodiment, the current measurement circuit and the voltage measurement circuit are respectively connected to the single-chip microcomputer. The single-chip microcomputer is respectively connected to the constant current source and the human-computer interaction device. The constant current source is connected to the four-probe probe;

[0041] In this embodiment, the single-chip microcomputer is connected to the input end of the barrier voltage generation circuit. The output end of the barrier voltage generation circuit is connected to the second probe and the third probe. Positive and negative polarity pulse signals are output between the second probe and the third probe of the four-probe probe to eliminate the barrier formed when the probe contacts the sample to be measured;

[0042] In this embodiment, the barrier voltage generation circuit is provided with a barrier voltage knob for adjusting the voltage value of the pulse signal, and the voltage range is 8-12V;

[0043] In this embodiment, the human-computer interaction device is used to set the pulse width. Specifically, the human-computer interaction module communicates with the single-chip microcomputer through RS232, sets the duration of the high and low levels, and transmits it to the barrier voltage generation circuit through the single-chip microcomputer;

[0044] In this embodiment, the constant current source is used to output a constant current. The constant current source is adjusted so that a stable current is output on the surface of the sample to be measured through a four-probe probe. The constant current source is provided with current selection gears. The single-chip microcomputer is connected to the current selection gears of the constant current source. The current output range of the constant current source in this embodiment is continuously adjustable from 1 mA to 500 mA. By using three standard resistors with different resistance values of 10 ohms, 1 ohm, and 0.1 ohm, the constant current source is changed into three sub-ranges of 1-10 mA, 10-100 mA, and 100-500 mA respectively. In this way, according to U = IR, no matter how large the output current is, the voltage on the standard resistor is within 10-100 mV. Thus, only one set of voltmeters with a certain range is needed to accurately obtain the magnitude of the stable output current.

[0045] In this embodiment, when the barrier voltage generating circuit contacts the sample to be measured, the constant current source switch is turned off. By pressing the barrier voltage switch button on the instrument panel, the output end of the barrier voltage generating circuit applies a low-voltage pulse signal with a positive polarity between the second probe and the third probe to eliminate the barrier formed when the probe contacts the sample. The pulse voltage and pulse width are adjustable. The pulse voltage is adjusted by the barrier voltage knob on the instrument panel, and the voltage range is 8-12 V. After the knob is adjusted, the voltage value remains stable. The voltage value needs to be adjusted according to the height of the sample barrier. If the barrier is too high to be broken through, the voltage value is increased. The pulse width of the barrier voltage is adjusted through the human-machine interaction module, and the adjustable time range is 10-2550 ms. Then the low level is pulled down for a period of time, and the duration (low-level pulse width) can also be adjusted through the human-machine interaction module, with an adjustable range of 100-10000 ms. After the duration ends, a reverse voltage is applied, that is, a voltage value and time identical to the positive voltage are applied from the third probe to the second probe. The high-level time of the positive and reverse voltages is the same, and the duration of the high and low levels is set by the human-machine interaction module and then transmitted to the single-chip microcomputer. The single-chip microcomputer saves the duration, and then the constant current source switch is turned on. The stable measured current flowing through the first probe and the fourth probe is measured through the current measurement circuit, and the potential difference existing between the second probe and the third probe after being pressed on the specified area of the sample to be measured is measured through the voltage measurement circuit. The measured current value and potential difference are sent to the single-chip microcomputer and then sent to the human-machine interaction module to calculate the resistivity value;

[0046] In this embodiment, the human-machine interaction device adjusts the pulse width of the barrier voltage and is used to calculate the resistivity of the material to be measured according to the current value and voltage value of the contact area between the four-probe probe and the sample to be measured after the barrier voltage is applied. The operation principle formula of the resistivity ρ is as follows:

[0047]

[0048] Among them, ρ is the resistivity of the material to be measured, V is the voltage value of the measured contact area in mV; I is the current value of the measured contact area in mA; W is the thickness value of the sample to be measured in cm; F sp is the probe spacing correction coefficient, the factory calibration parameter of the four-probe; F(W / S) is the thickness correction coefficient, and its value can be found in the national standard; F(S / D) is the diameter correction coefficient, and its value can be found in the national standard; F t is the temperature correction coefficient, and its value can be found in the national standard.

[0049] As Figure 3 shown, the barrier voltage cancellation circuit is provided with a control circuit for positive and negative polarity pulse signals, including: the first relay K8, the second relay K9, the capacitor C27, the power supply VCC terminal, and the ground terminal;

[0050] Among them, the first pair of normally open contacts of the first relay K8 are respectively connected to the second probe of the four-probe head and the first common terminal of the second relay K9, and the normally closed contact and the normally open contact corresponding to the first common terminal are respectively connected to the power supply VCC terminal and the ground terminal;

[0051] The second pair of normally open contacts of the first relay K8 are respectively connected to the third probe of the four-probe head and the second common terminal of the second relay K9, and the normally closed contact and the normally open contact corresponding to the second common terminal are respectively connected to the ground terminal and the power supply VCC terminal;

[0052] Both ends of the capacitor C27 are respectively connected to the second probe and the third probe of the four-probe head;

[0053] The voltage of the power supply VCC terminal is adjusted by the barrier voltage cancellation knob, and the voltage range is 8 - 12V;

[0054] The single-chip microcomputer is used to control the first pair of normally open contacts and the second pair of normally open contacts of the first relay K8 to close, and output a positive polarity pulse signal. The single-chip microcomputer controls the first pair of normally open contacts and the second pair of normally open contacts of the first relay K8, and the normally open contacts corresponding to the first common terminal and the second common terminal of the second relay K9 to close, and output a negative polarity pulse signal.

[0055] As Figure 4 shown, the relay K8 control circuit is also provided in the barrier voltage cancellation circuit, including: the first resistor R55, the first triode VT14, and the first diode VD31;

[0056] One end of the first resistor R55 is connected to the second output IO port of the single-chip microcomputer. The second output IO port corresponds to the second pin of the single-chip microcomputer signal connection socket P11. The other end of the first resistor R55 is connected to the base of the first triode VT14. The emitter of the first triode VT14 is grounded. The collector of the first triode VT14 is connected to one end of the coil of the first relay K8. The other end of the coil of the first relay K8 is connected to the positive power supply. The positive pole of the first diode VD31 is connected to one end of the coil of the first relay K8. The negative pole of the first diode VD31 is connected to the other end of the coil of the first relay K8.

[0057] As Figure 4 shown, the barrier voltage elimination circuit further includes a relay K9 control circuit, which includes: a second resistor R58, a second triode VT15, and a second diode VD34;

[0058] One end of the second resistor R58 is connected to the first output IO port. The first output IO port corresponds to the first pin of the single-chip microcomputer signal connection socket P11. The other end of the second resistor R58 is connected to the base of the second triode VT15. The emitter of the second triode VT15 is grounded. The collector of the second triode VT15 is connected to one end of the coil of the second relay K9. The other end of the coil of the second relay K9 is connected to the positive power supply. The positive pole of the second diode VD34 is connected to one end of the coil of the second relay K9. The negative pole of the second diode VD34 is connected to the other end of the coil of the second relay K9.

[0059] In this embodiment, when the single-chip microcomputer detects that the circuit of the constant current source is disconnected and the barrier voltage elimination switch button is turned on, it sends pulses through the first output IO port and the second output IO port to control two groups of relays. That is, the first pin and the second pin corresponding to the single-chip microcomputer signal connection socket P11 are at a high level, and a low-voltage pulse signal with positive and negative polarities is applied between the second probe and the third probe of the four-probe probe. The single-chip microcomputer controls the switches of the two groups of relays to control the conduction time and direction of the 8-12V voltage circuit. When the second output IO port outputs a high level, it controls the relay K8 to close, and the voltage output by the adjustable voltage stabilizing circuit is conducted in the forward direction of 8-12V, from the second probe to the third probe. Subsequently, the second IO port outputs a low level to control the relay K8 to disconnect. After an interval of time, the first output IO port and the second output IO port of the single-chip microcomputer output high levels at the same time to control the relay K8 and the relay K9 to close simultaneously, forming a reverse voltage from the third probe to the second probe, thereby forming a barrier voltage elimination voltage.

[0060] In this embodiment, the single-chip microcomputer is further provided with a third output IO port. The third output IO port corresponds to the third pin of the single-chip microcomputer signal connection socket P11. One end of the third output IO port is connected to one end of the constant current source switch, and the other end of the constant current source switch is connected to the positive power supply. The positive power supply of this embodiment is preferably 12V;

[0061] The measuring device for the resistivity of the semiconductive compound semiconductor in this embodiment measures the resistivity of the semiconductive semiconductor based on the principle of eliminating the contact barrier, without the need to cut the sample piece, belonging to non-destructive measurement. By using the set breakdown voltage to eliminate the contact barrier formed between the metal and the semiconductive semiconductor, the contact resistance can be greatly reduced, enabling the accurate measurement of the resistivity of the semiconductive compound by the four-probe method. The sample is placed on the sample stage, and the probe is positioned above the point on the sample that needs to be tested. The potential-barrier elimination voltage generating circuit applies a low-voltage pulse signal between the second probe and the third probe of the four-probe probe in contact with the sample piece on the sample stage. The amplitude and width of the pulse signal are controllable. The resistivity of the sample is calculated according to the voltage change of each measurement point collected by the four-probe probe, and the distributed measurement of the resistivity of the semiconductive semiconductor material can be realized, accurately reflecting the overall performance of the material.

[0062] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A device for measuring the resistivity of a semiconducting compound semiconductor, characterized in that: include: Four-probe probe, voltage measurement circuit, current measurement circuit, barrier elimination voltage generation circuit, constant current source, single-chip microcomputer, human-computer interaction equipment; The four-probe probe is respectively provided with a first probe, a second probe, a third probe and a fourth probe, the first probe and the fourth probe are connected to the current measurement circuit, and the second probe and the third probe are connected to the voltage measurement circuit; The current measurement circuit and the voltage measurement circuit are respectively connected to the single chip microcomputer, the single chip microcomputer is respectively connected to the constant current source and the human-computer interaction device, and the constant current source is connected to the four-probe probe; The single chip microcomputer is connected to the input end of the potential barrier elimination voltage generating circuit, and the output end of the potential barrier elimination voltage generating circuit is connected to the second probe and the third probe, and a pulse signal of positive and reverse polarity is output between the second probe and the third probe of the four-probe probe to eliminate the potential barrier formed when the probe contacts the sample to be tested; The barrier elimination voltage generating circuit is provided with a barrier elimination voltage knob, and the barrier elimination voltage knob is used to adjust the voltage value of the pulse signal; The human-computer interaction device is used to set the pulse width, and transmit it to the potential barrier elimination voltage generation circuit through the single-chip microcomputer to calculate the resistivity of the sample to be tested after the potential barrier is eliminated; The constant current source is used to output a constant current.

2. The device for measuring resistivity of a semiconducting compound semiconductor according to claim 1, characterized in that: The four-probe probes are pressed into contact with the positions to be tested on the surface of the sample to be tested through the transport control rails.

3. The device for measuring resistivity of a semiconducting compound semiconductor according to claim 1, characterized in that: The four-probe probe adopts an in-line four-probe probe.

4. The device for measuring resistivity of a semiconducting compound semiconductor according to claim 1, characterized in that: The potential elimination barrier voltage generating circuit is provided with a control circuit of a pulse signal of positive and reverse polarity, including: a first relay K8, a second relay K9, a capacitor, a power supply VCC terminal, and a ground terminal; The first pair of normally open contacts of the first relay K8 are respectively connected to the second probe of the four-probe probe and the first common terminal of the second relay K9, and the normally closed contact and normally open contact corresponding to the first common terminal are respectively connected to the power supply VCC terminal and the ground terminal; The second pair of normally open contacts of the first relay K8 are respectively connected to the third probe of the four-probe probe and the second common terminal of the second relay K9, and the normally closed contact and normally open contact corresponding to the second common terminal are respectively connected to the ground terminal and the power supply VCC terminal; The two ends of the capacitor are respectively connected to the second probe and the third probe of the four-probe probe; The voltage at the power supply VCC end is adjusted by the potential elimination voltage knob. The single-chip microcomputer is used to control the closure of the first pair of normally open contacts and the second pair of normally open contacts of the first relay K8, and output a pulse signal of positive polarity. The single-chip microcomputer controls the closure of the first pair of normally open contacts and the second pair of normally open contacts of the first relay K8, and the normally open contacts corresponding to the first common end and the second common end of the second relay K9, and outputs a pulse signal of reverse polarity.

5. The device for measuring resistivity of a semiconducting compound semiconductor according to claim 4, characterized in that: The potential elimination barrier voltage generating circuit is also provided with a relay K8 control circuit, including: a first resistor R55, a first transistor VT14, and a first diode VD31; One end of the first resistor R55 is connected to the second output IO port of the single-chip microcomputer, the other end of the first resistor R55 is connected to the base of the first transistor VT14, the emitter of the first transistor VT14 is grounded, the collector of the first transistor VT14 is connected to one end of the first relay K8 coil, the other end of the first relay K8 coil is connected to the positive electrode of the power supply, the positive electrode of the first diode VD31 is connected to one end of the first relay K8 coil, and the negative electrode of the first diode VD31 is connected to the other end of the first relay K8 coil.

6. The device for measuring resistivity of a semiconducting compound semiconductor according to claim 4, characterized in that: The potential elimination barrier voltage generating circuit is also provided with a relay K9 control circuit, including: a second resistor R58, a second transistor VT15, and a second diode VD34; One end of the second resistor R58 is connected to the first output IO port, the other end of the second resistor R58 is connected to the base of the second transistor VT15, the emitter of the second transistor VT15 is grounded, the collector of the second transistor VT15 is connected to one end of the second relay K9 coil, the other end of the second relay K9 coil is connected to the positive electrode of the power supply, the positive electrode of the second diode VD34 is connected to one end of the second relay K9 coil, and the negative electrode of the second diode VD34 is connected to the other end of the second relay K9 coil.

7. The device for measuring resistivity of a semiconducting compound semiconductor according to claim 1, characterized in that: The single chip microcomputer is also provided with a third output IO port, the third output IO port is connected to one end of a constant current source switch, and the other end of the constant current source switch is connected to the positive pole of the power supply.

8. The device for measuring resistivity of a semiconducting compound semiconductor according to claim 1, characterized in that: The constant current source is provided with a current selection gear, and the single chip microcomputer is connected with the current selection gear of the constant current source.

9. The device for measuring resistivity of a semiconducting compound semiconductor according to claim 8, characterized in that: The current selection range includes 1~10mA, 10~100mA, and 100~500mA.

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