Germanium single crystal detection method

Abstract

The detection method of the germanium single crystal comprises the following steps: S1, preparing a sample wafer of the germanium single crystal; s2, manufacturing four ohmic electrodes on the sample wafer; s3, enabling the four probes of the Hall detection clamp to be in contact with the four ohmic electrodes respectively; and S4, starting the Hall detector for detection. Wherein in the step S1, four notches are respectively formed in four side surfaces of the sample wafer; in the step S2, the four ohmic electrodes are formed in the four notches respectively; in the step S3, each probe of the Hall detection clamp is inserted into the ohmic electrode in the corresponding notch in a manner of facing the corresponding side surface of the sample wafer. As the tail ends of the probes of the Hall detection clamp are the same in shape and size and operation stroke, when the probes are inserted into the ohmic electrode and the tail ends are in point contact with the ohmic electrode, the contact surfaces of point contact are the same, and the repeatability, the stability and the accuracy of the detection result of the Hall detector are ensured.

Description

Technical Field

[0001] The present disclosure relates to the field of germanium materials, and in particular to a method for detecting germanium single crystals. Background Art

[0002] A voltage is applied in the length direction of the semiconductor sample and a magnetic field is applied in the width direction. Due to the effect of the magnetic field, a Lorentz force is generated in the height direction. This phenomenon is called the Hall effect. The Lorentz force causes the carriers moving in the semiconductor sample to accumulate above the sample, thus generating an electric field on the top and bottom of the sample (in the height direction). The electric force generated by the electric field is balanced with the Lorentz force. This phenomenon is used to perform Hall detection on the semiconductor sample.

[0003] When performing low-temperature Hall detection, high requirements are placed on the sample and electrode contact, such as: the sample thickness should be uniform, the sample surface should be flat without holes or grooves, the electrode contact position should be at the edge of the sample, and the area of ​​the electrode contact point should be small enough.

[0004] In the field of Hall detection of germanium, the current conventional detection method is to first cut a sample with a thickness of less than 1 mm, then cut the sample into small square samples, and finally make indium electrodes at the four corners of the sample for Hall detection. For example, the published Chinese patents CN114577561A and CN114235899A both use similar methods; although the temperature of thinner samples can be easily and quickly reduced to 77K, the detection efficiency is higher, but when using a wire cutting machine to cut crystal samples, thickness errors are inevitable. The thinner the sample thickness, the greater the impact of the sample thickness error on the test results, which is not conducive to the accuracy of the test results.

[0005] Ultra-high purity germanium is the pinnacle of high purity materials, with a carrier concentration of less than 2E10 / cm 3 The purity can reach 13N, and the resistivity can reach several thousand to tens of thousands. Such special high-resistance materials have extremely high requirements for Hall detection methods and detection equipment. The detection methods and equipment currently used are prone to unstable detection results and poor repeatability, and even the accuracy of the detection results cannot be guaranteed. Summary of the invention

[0006] In view of the problems existing in the background technology, an object of the present disclosure is to provide a method for detecting a germanium single crystal, which can ensure the stability, repeatability and accuracy of the detection results.

[0007] Thus, a method for detecting germanium single crystal includes the following steps: S1, preparing a sample of germanium single crystal; S2, making four ohmic electrodes on the sample; S3, making four probes of the Hall detection fixture contact the four ohmic electrodes respectively; S4, starting the Hall detector for detection. In step S1, the sample is provided with four notches on four sides respectively; in step S2, the four ohmic electrodes are formed in the four notches respectively; in step S3, each probe of the Hall detection fixture is inserted into the ohmic electrode in the corresponding notch facing the corresponding side of the sample.

[0008] The beneficial effects of the present disclosure are as follows: in the detection method of germanium single crystal according to the present disclosure, since the four ohmic electrodes are respectively formed in the four notches, when the probes of the Hall detection fixture are respectively inserted into the ohmic electrodes in the corresponding notches facing the corresponding sides of the sample, the parts of the probes inserted into the ohmic electrodes form point contacts with the ohmic electrodes. Since the ends of the probes of the Hall detection fixture are the same in shape and size and the same in operating stroke, when the probes are inserted into the ohmic electrodes and the ends point-contact the ohmic electrodes, the contact surfaces of the point contacts are the same. In this way, the repeatability, stability and accuracy of the detection results of the Hall detector are guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a stereoscopic view of a sample of a germanium single crystal prepared according to step S1 of the method for inspecting a germanium single crystal disclosed in the present invention.

[0010] Figure 2 1 is a top view schematic diagram of four probes of a Hall detection fixture connected to four ohmic electrodes respectively in step S3 of the method for detecting a germanium single crystal disclosed in the present invention, wherein: Figure 2 The sample piece is made along the horizontal plane formed by the centers of the four notches.

[0011] Figure 3 is a side view schematic diagram of four probes of the Hall detection fixture connected to four ohmic electrodes respectively in step S3 of the detection method of germanium single crystal disclosed in the present invention, wherein: Figure 3 The sample is made along the vertical plane of the sample passing through the center of two opposite notches. DETAILED DESCRIPTION

[0012] The accompanying drawings show embodiments of the present disclosure, and it will be understood that the disclosed embodiments are merely examples of the present disclosure, and the present disclosure can be implemented in various forms. Therefore, the specific details disclosed herein should not be interpreted as limiting, but merely as the basis for the claims and as a representative basis for teaching ordinary technicians in the field to implement the present disclosure in various ways.

[0013] [Detection method of germanium single crystal]

[0014] Reference Figures 1 to 3According to the present invention, the detection method of germanium single crystal includes the steps of

[0015] S1, prepare a sample of germanium single crystal;

[0016] S2, make four ohmic electrodes on the sample;

[0017] S3, connecting the four probes of the Hall detection fixture to four ohmic electrodes respectively;

[0018] S4, start the Hall detector to perform detection;

[0019] Wherein, in step S1, four notches are respectively provided on four sides of the sample;

[0020] In step S2, four ohmic electrodes are formed in four recesses respectively;

[0021] In step S3, each probe of the Hall detection fixture is inserted into the ohmic electrode in the corresponding notch facing the corresponding side surface of the sample.

[0022] In the detection method of the germanium single crystal according to the present disclosure, since the four ohmic electrodes are respectively formed in the four notches, when the probes of the Hall detection fixture are respectively inserted into the ohmic electrodes in the corresponding notches facing the corresponding side surfaces of the sample, the parts of the probes inserted into the ohmic electrodes form point contacts with the ohmic electrodes. Figure 2 and Figure 3 The two electrodes (shown as pointed cones) are the same in size and operating stroke, so when the ohmic electrode is inserted and the end contacts the ohmic electrode, the contact surface of the point contact is the same. In this way, the repeatability, stability and accuracy of the detection results of the Hall detector are guaranteed.

[0023] In one example, the step S1 of preparing a sample of a germanium single crystal includes: cutting the crystal perpendicular to the crystal growth axis, taking a sample, and the thickness of the sample is (2.0±0.1) mm-(4.0±0.1) mm. Compared with the sample thickness less than 1 mm required by the background technology, the sample of the germanium single crystal in this example has a large thickness, and the sample thickness error caused by cutting has little effect on the test results, further enhancing the repeatability, stability and accuracy of the test results.

[0024] In one example, the upper and lower surfaces of the sample piece are squares with side lengths of (10±0.1) mm to (15±0.1) mm.

[0025] like Figure 1 As shown, each notch is formed at the center of the corresponding side surface, so that it can match the 90-degree configuration of the four probes, avoiding measurement inconvenience caused by the difference in notch position.

[0026] In one example, the diameter of each notch is 1.0-1.5 mm and is smaller than the thickness of the germanium single crystal sample, and the depth of each notch is less than 0.5 mm. This ensures that the upper and lower surfaces of the sample are complete surfaces, and each notch is a small contact point of an ohmic electrode.

[0027] In one example, the step S1 of preparing the sample of the germanium single crystal further includes: repeatedly scratching each notch with a diamond pen to increase the surface roughness of the notch. This operation can form the bonding ability of the ohmic electrode in the notch, reduce the occurrence of bubbles and cold solder joints in the formed ohmic electrode, make the current and voltage after the probe contacts the ohmic electrode more stable and accurate, and further enhance the stability, repeatability and accuracy of the test results.

[0028] In one example, the step S1 of preparing a sample of a germanium single crystal further includes: corroding the sample in an etching solution of HNO3:HF=(2-4):1, then rinsing the sample with pure water for a rinsing time of not less than 15 minutes, preferably 20-30 minutes, and finally drying with high-purity nitrogen. Specifically, the rinsing time is 20-30 minutes, and the purity of the high-purity nitrogen is above 7N.

[0029] In one example, the step S2 of making four ohmic electrodes on the sample includes: injecting a Hg—In alloy having 50-60 wt % In at 25° C. into each of the recesses.

[0030] In one example, the starting of the Hall detector for detection in step S4 includes sub-steps: S41, open the Hall detection software, input the sample information and measurement parameters, and perform a contact test on the sample; S42, after confirming that the contact test is OK, place the Hall test fixture in the liquid nitrogen well, then add liquid nitrogen to the liquid nitrogen well, wait for 3-5 minutes, and ensure that the sample is cooled to 77k; S43, test the positive and negative voltages and currents between each electrode in the positive magnetic field direction, then change the magnetic field direction, re-test the positive and negative voltages and currents between each electrode in turn, and finally convert the low-temperature carrier concentration, resistivity, mobility, Hall coefficient, F value, etc., and record them in the table; S44, take out the Hall test fixture from the liquid nitrogen well, use warm air to blow to room temperature, re-test the sample according to sub-steps S41 to S43, record them in the table, and complete the Hall test. Specifically, in step S41, the sample information and measurement parameters input include sample thickness, detection temperature, and magnetic induction intensity.

[0031] [test]

[0032] Example 1

[0033] Example 1 adopts the following steps:

[0034] S1, preparing a sample of a germanium single crystal, including sub-steps:

[0035] S11, cut the crystal perpendicular to the crystal growth axis and take a sample. The thickness of the sample is (3.0±

[0036] 0.1) mm, the upper and lower surfaces of the specimen are squares with a side length of (12 ± 0.1) mm;

[0037] S12, sawing four notches at the center positions of the four sides of the sample, respectively, the diameter of each notch is 1.2 mm (less than the thickness of the germanium single crystal sample), and the depth of each notch is 0.4 mm;

[0038] S13, use a diamond pen to repeatedly scratch each notch to increase the surface area of ​​the notch.

[0039] Surface roughness;

[0040] S14, place the sample in a HNO3:HF=3:1 etching solution, and then rinse with pure water.

[0041] Wash the sample for 25 minutes and finally blow dry with 7N high-purity nitrogen;

[0042] S2, injecting a Hg-In alloy containing 52 wt% In at 25° C. into each notch, and four ohmic electrodes are formed in the four notches, respectively, thereby making four ohmic electrodes on the sample;

[0043] S3, each probe of the Hall detection fixture is inserted into the ohmic electrode in the corresponding notch facing the corresponding side of the sample, so that the four probes of the Hall detection fixture are in contact with the four ohmic electrodes respectively;

[0044] S4, starting the Hall detector to perform detection, including sub-steps:

[0045] S41, opening the Hall detection software, inputting the sample information and measurement parameters, and performing the sample contact test, wherein the input sample information and measurement parameters include the sample thickness, the detection temperature, and the magnetic induction intensity;

[0046] S42, after confirming that the contact test is OK, place the Hall test fixture in the liquid nitrogen well, then add liquid nitrogen to the liquid nitrogen well and wait for 4 minutes to ensure that the sample is cooled to 77K;

[0047] S43, in the positive magnetic field direction, respectively test the positive and negative voltages and currents between the electrodes, then change the magnetic field direction, and re-test the positive and negative voltages and currents between the electrodes, and finally convert the low-temperature carrier concentration, resistivity, mobility, Hall coefficient, F value, etc., and record them.

[0048] Record in the form;

[0049] S44, take out the Hall test fixture from the liquid nitrogen well, use warm air to blow it to room temperature, retest the sample according to sub-steps S41 to S43, record it in the table, and complete the Hall test.

[0050] The above steps were repeated four times for two samples (sample A and sample B) prepared from the same batch. The test results are shown in Table 1.

[0051] Table 1 Test results of two samples prepared from the same batch

[0052]

[0053]

[0054] It can be seen from Table 1 that the method for detecting high-purity germanium single crystals by the method adopted in Example 1 can ensure the stability, repeatability and accuracy of the detection results.

[0055] The above detailed description is used to describe 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 together to form multiple additional combinations that are not shown for the sake of simplicity.

Claims

1. A method for detecting a germanium single crystal, comprising the steps of: S1, prepare a sample of germanium single crystal; S2, make four ohmic electrodes on the sample; S3, making the four probes of the Hall detection fixture contact the four ohmic electrodes respectively; S4, start the Hall detector to perform detection; It is characterized in that In step S1, the sample is provided with four notches on four sides respectively; In step S2, four ohmic electrodes are formed in four recesses respectively; In step S3, each probe of the Hall detection fixture is inserted into the ohmic electrode in the corresponding notch facing the corresponding side surface of the sample.

2. The method for detecting germanium single crystal according to claim 1, characterized in that: The step S1 of preparing a sample of a germanium single crystal includes: cutting the crystal perpendicular to the crystal growth axis to obtain a sample, wherein the thickness of the sample is (2.0±0.1) mm-(4.0±0.1) mm; The upper and lower surfaces of the specimen are squares with side lengths of (10±0.1) mm to (15±0.1) mm.

3. The method for detecting germanium single crystal according to claim 1, characterized in that: Each notch is formed at a center position of a corresponding side surface.

4. The method for detecting germanium single crystal according to claim 1, characterized in that: The diameter of each notch is 1.0-1.5 mm and is smaller than the thickness of the germanium single crystal sample, and the depth of each notch is less than 0.5 mm.

5. The method for detecting germanium single crystal according to claim 1, characterized in that: The step S1 of preparing the germanium single crystal sample also includes: repeatedly scratching each notch with a diamond pen to increase the surface roughness of the notch.

6. The method for detecting germanium single crystal according to claim 5, characterized in that: The step S1 of preparing the germanium single crystal sample also includes: corroding the sample in a corrosion solution of HNO3:HF=(2-4):1, then rinsing the sample with pure water for a rinsing time of not less than 15 minutes, preferably 20-30 minutes, and finally drying with high-purity nitrogen.

7. The method for detecting germanium single crystal according to claim 6, characterized in that: The flushing time is 20-30 minutes, and the purity of high-purity nitrogen is above 7N.

8. The method for detecting germanium single crystal according to claim 5, characterized in that: Step S2 of making four ohmic electrodes on the sample includes injecting a Hg-In alloy containing 50-60 wt % In at 25° C. into each of the recesses.

9. The method for detecting germanium single crystal according to claim 1, characterized in that: The step S4 of starting the Hall detector to perform detection includes the following sub-steps: S41, open the Hall detection software, input the sample information and measurement parameters, and perform the sample contact test; S42, after confirming that the contact test is OK, place the Hall test fixture in the liquid nitrogen well, then add liquid nitrogen to the liquid nitrogen well and wait for 3-5 minutes to ensure that the sample is cooled to 77K; S43, testing the positive and negative voltages and currents between the electrodes in the positive magnetic field direction, then changing the magnetic field direction, testing the positive and negative voltages and currents between the electrodes again, and finally converting the low-temperature carrier concentration, resistivity, mobility, Hall coefficient, F value, etc., and recording them in a table; S44, take out the Hall test fixture from the liquid nitrogen well, use warm air to blow it to room temperature, retest the sample according to sub-steps S41 to S43, record it in the table, and complete the Hall test.

10. The method for detecting germanium single crystal according to claim 9, characterized in that: In step S41, the input sample information and measurement parameters include sample thickness, detection temperature, and magnetic induction intensity.

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