Method for detecting minority carrier lifetime

Abstract

The invention discloses a minority carrier lifetime detection method, and relates to the technical field of semiconductor detection, and the method comprises the following steps: S1, preparing a test sample; s2, modulating an obtained photoconductive signal on a 10-10.5 GHz high-frequency carrier wave through capacitive coupling between a sample and an electrode; s3, taking out the photoconductive signal; s4, loading two ends of the sample with a high-frequency power supply of 25-35MHz; s5, irradiating the sample with laser with the wavelength of 904 nm to modulate high-frequency signals at the two ends of the sample; s6, after 3-5 min, illumination is stopped; s7, increasing a photoconductive attenuation signal; and S8, measuring the minority carrier lifetime of the sample through the attenuation curve. According to the method, in order to improve the test effect, a photoconduction signal is increased between a sample and an electrode, so that the detection accuracy of the method is improved, xenon lamps are used as light sources in optical systems of the method and a direct-current photoconduction recession method, but a cold cathode thyratron is used for gate control, and the detection accuracy of the method can be further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor detection, in particular to a minority carrier lifetime detection method. BACKGROUND

[0002] Minority carrier lifetime is an important parameter of semiconductor materials, and is also a basic parameter for evaluating the quality of semiconductor materials. With the wide application of semiconductor materials, its testing and analysis technology has always attracted people's attention, such as the development and wide application of many technologies such as direct current photoconductance decay technology, surface photovoltage technology, alternating current photocurrent phase technology and microwave photoconductance decay technology. However, due to the differences in light (electricity) injection amount, test frequency, temperature and other parameters of different test technologies, the test values of the same semiconductor material on different test equipment often differ greatly, and the error range even reaches more than 100%, therefore, accurate measurement of the minority carrier lifetime of semiconductor materials is the focus of people's attention.

[0003] The minority carrier lifetime of semiconductor materials not only characterizes the quality of semiconductor materials, but also evaluates the quality control in the process of device manufacturing, such as the use of carrier lifetime by integrated circuit companies to characterize the degree of metal contamination in the process, and to study the causes of device performance degradation. Therefore, with the development of semiconductor device technology, the testing equipment of the minority carrier lifetime of semiconductor materials requires higher and higher, from the early contact measurement of block materials, to the non-destructive, non-contact and non-polluting measurement of sheet materials.

[0004] In the invention patent with publication (announcement) number: CN108680850B, publication (announcement) date: 2020-07-14, and the name of a minority carrier lifetime detection method, it includes: obtaining the bulk minority carrier lifetime value; obtaining the bulk distribution characteristic parameter; obtaining the minority carrier lifetime density and the effective minority carrier lifetime according to the bulk minority carrier lifetime value and the bulk distribution characteristic parameter. The present application obtains the bulk minority carrier lifetime value at the same time, and also obtains the semiconductor layer bulk distribution characteristic parameter, combines the bulk minority carrier lifetime value and the bulk distribution characteristic parameter to obtain the minority carrier lifetime density and the effective minority carrier lifetime. The detection method has high accuracy, and is beneficial to truly reflecting the minority carrier lifetime and the performance of the semiconductor layer material.

[0005] In the prior art including the above-mentioned patent, the method for detecting the minority carrier lifetime can detect the quality of the semiconductor in most cases, but the general detection method needs to cut the sample, which cannot guarantee the integrity of the sample, and the whole test process is relatively complicated. At the same time, the method does not increase the photoconductivity signal, which cannot improve the test accuracy of the method, and the actual application effect is not good, and an urgent need for a minority carrier lifetime detection method. SUMMARY

[0006] The present application aims to provide a kind of minority life detection method to solve the above-mentioned deficiencies in prior art.

[0007] In order to achieve the above-mentioned purposes, the present application provides the following technical solutions:

[0008] A kind of minority life detection method, the method comprises the following steps:

[0009] S1, prepare test sample;

[0010] S2, by the capacitance coupling between sample and electrode, the obtained photoconductive signal is modulated on 10-10.5GHz high frequency carrier;

[0011] S3, photoconductive signal is taken out;

[0012] S4, using 25-35MHz high frequency power supply, load in the two ends of sample;

[0013] S5, using wavelength 904nm laser irradiation on sample, so that the high frequency signal of the two ends of sample is modulated;

[0014] S6, after 3-5min, stop light;

[0015] S7, increase photoconductive decay signal;

[0016] S8, the minority life of sample is measured by decay curve.

[0017] As a further description of the above technical solutions:

[0018] The test sample in S1 is tellurium cadmium mercury material, and its appearance is guaranteed to be intact during testing;And the injection ratio of the test sample is less than 1%.

[0019] As a further description of the above technical solutions:

[0020] In S3, photoconductive signal is taken out by detection, and photoconductive signal can be taken out from sampling resistance or directly modulated from the two ends of sample.

[0021] As a further description of the above technical solutions:

[0022] In S5, light irradiation is used on sample, non-equilibrium minority carriers are generated in sample, so that the conductivity of sample increases, the resistance decreases, the high frequency voltage value of the two ends of sample decreases, and then the high frequency signal of the two ends of sample is modulated.

[0023] As a further description of the above technical solutions:

[0024] In S5, in order to improve the test effect, the following scheme is adopted, that is, heat-conducting silicone grease is applied between sample and electrode to increase the coupling between them.

[0025] As a further description of the above technical solution:

[0026] In the S5, the following scheme is used to improve the test effect: a variable capacitor is connected in series in the circuit to improve the matching of the circuit and increase the photoconductive signal.

[0027] As a further description of the above technical solution:

[0028] In the S5, the following scheme is used to improve the test effect: a variable capacitor is connected in series in the circuit to improve the matching of the circuit and increase the photoconductive signal.

[0029] As a further description of the above technical solution:

[0030] The variable capacitor is a porcelain dielectric trimmer capacitor, and the capacitance value range is 3-30 pF.

[0031] As a further description of the above technical solution:

[0032] In the S6, after the light is stopped, the non-equilibrium carriers in the sample decay according to an exponential law, gradually recombine and disappear, so the high-frequency voltage amplitude across the sample gradually returns to the level when there is no light. A diode detector and a capacitor filter are used to demodulate the high-frequency photoconductive signal.

[0033] As a further description of the above technical solution:

[0034] In the S7, the photoconductive decay signal is increased by a wide-band amplifier, and the bandwidth of the wide-band amplifier is greater than 5 MHz.

[0035] As a further description of the above technical solution:

[0036] In the S8, the amplified signal is added to a pulse oscilloscope, and a synchronization signal is connected to display an exponential decay curve on the fluorescent screen. The minority carrier lifetime of the sample is measured through the decay curve.

[0037] In the above technical solution, the present application provides a minority carrier lifetime detection method. In order to improve the test effect, the photoconductive signal between the sample and the electrode is increased, thereby improving the detection accuracy of the method. In terms of optical systems, the method uses a xenon lamp as a light source in the optical system of the direct current photoconductive decay method, but uses a cold cathode valve as a gate control, which can further improve the detection accuracy of the method.

[0038] It should be understood that the foregoing general description and the following detailed description are only exemplary and illustrative, but not for limiting the present disclosure.

[0039] This application file provides an overview of various implementations or examples of the technology described in this disclosure and is not intended to be comprehensive or disclose all the features of the disclosed technologies. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art based on these drawings.

[0041] Fig. 1 A flowchart of a minority carrier lifetime detection method.

[0042] Fig. 2 A test structure block diagram of a minority carrier lifetime detection method. DETAILED DESCRIPTION

[0043] In order to make the purposes, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be described clearly and completely in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present disclosure.

[0044] Embodiment 1

[0045] Referring to Figs. 1-2 As shown in the figure, the present application provides a minority carrier lifetime detection method, which comprises the following steps:

[0046] S1, preparing a test sample; the test sample is a tellurium cadmium mercury material, and its appearance is guaranteed to be intact during testing; and the injection ratio of the test sample is less than 1%.

[0047] Wherein, the injection ratio is ΔV / kV; in the formula, ΔV is the signal voltage value measured on the oscilloscope, k is the amplification multiple of the preamplifier, and V is the indication value of the voltmeter behind the detector. The sample injection ratio is the non-equilibrium carrier concentration ratio to the equilibrium carrier concentration. The injection ratio less than 1 is generally called low injection, and the injection ratio greater than 1 is called high injection. If the injection ratio is greater than 1, that is, in the case of high injection, the majority carrier concentration will change, and the test actually captures the recombination of the majority carrier. However, when it is less than 1, the carrier recombination follows the linear kinetic law, and the test signal is strictly proportional to the carrier concentration.

[0048] For the sample rod with high resistivity, the control of injection ratio should be paid special attention. Because the photoconductive signal is often large at this time, it is easy to make the reading of the measured data too large.

[0049] S2, modulate the obtained photoconductive signal on a 10GHz high-frequency carrier through the capacitive coupling between the sample and the electrode;

[0050] S3, take out the photoconductive signal; the photoconductive signal can be taken out from the sampling resistor or directly taken out from the two ends of the sample through detection.

[0051] S4, load a 25MHz high-frequency power source at the two ends of the sample;

[0052] S5, irradiate the sample with a laser with a wavelength of 904nm to modulate the high-frequency signal at the two ends of the sample; the light irradiation on the sample generates unbalanced minority carriers in the sample, increases the conductivity of the sample, reduces the resistance, and reduces the high-frequency voltage value at the two ends of the sample, thereby modulating the high-frequency signal at the two ends of the sample.

[0053] Among them, the following scheme is adopted to improve the test effect: a heat-conducting silicone grease is applied between the sample and the electrode to increase the coupling between them.

[0054] S6, stop the light irradiation for 3min; after stopping the light irradiation, the unbalanced carriers in the sample decay according to an exponential law and gradually recombine and disappear, so the high-frequency voltage amplitude at the two ends of the sample gradually returns to the level when there is no light irradiation. Diode detection plus capacitive filtering is adopted to demodulate the high-frequency photoconductive signal.

[0055] S7, increase the photoconductive decay signal; the photoconductive decay signal is increased through a wideband amplifier with a bandwidth greater than 5MHz.

[0056] S8, measure the minority carrier lifetime of the sample through the decay curve; the amplified signal is added to a pulse oscilloscope, a synchronization signal is connected, and an exponential decay curve is displayed on the fluorescent screen. The minority carrier lifetime of the sample is measured through the decay curve.

[0057] Among them, the initial part of the decay curve is fast decay, which should be removed during the measurement. Fast decay is often caused by surface recombination. The non-penetrating light is removed by a silicon filter, which often eliminates it. In addition, the head part of the signal amplitude (about 1 / 3 of the amplitude) should be removed before reading.

[0058] Trapping effect: When non-equilibrium charge carriers are present, the number of electrons in certain impurity energy levels of a semiconductor changes, leading to the accumulation of charge carriers. This effect of accumulating non-equilibrium charge carriers is called the trapping effect. Generally, an increase in the number of electrons can be considered as the accumulation of electrons, and a decrease in the number of electrons can be considered as the accumulation of holes. Under normal circumstances, non-equilibrium charge carriers that fall into the trap often take a relatively long time to be gradually released, thus causing the decay rate in the latter half of the decay curve to slow down, the so-called "tail".

[0059] The "flat-top" phenomenon in the attenuation curve can be caused by two factors: First, the high-frequency oscillation voltage is too high. In this case, reducing the output power of the high-frequency oscillator will improve the situation. Second, the flash intensity is too strong. Reducing the flash discharge voltage, adding a silicon filter, or reducing the aperture of the aperture lamp can all correct the waveform.

[0060] The lower limit for measuring minority carrier lifetime using the high-frequency photoconductivity decay method is approximately ten microseconds (determined by the cutoff time of the light pulse), while the upper limit is several thousand microseconds. Due to limitations imposed by the intensity of the pulsed light, the resistivity of the single crystal rod is generally required to be greater than 10² Ω·cm; too low a resistivity will result in a photoconductivity signal that is too weak to be observed.

[0061] Example 2

[0062] Reference Figs. 1-2 As shown, the present invention provides a minority carrier lifetime detection method, which includes the following steps:

[0063] S1. Prepare the test sample; the test sample is mercury cadmium telluride material, and its appearance must be intact during the test; and the injection ratio of the test sample is less than 1%.

[0064] The injection ratio is ΔV / kV; where ΔV is the signal voltage value measured on the oscilloscope, k is the amplification factor of the preamplifier, and V is the voltmeter reading after the detector. The sample injection ratio is the ratio of non-equilibrium carrier concentration to equilibrium carrier concentration. An injection ratio less than 1 is generally considered low injection, and an injection ratio greater than 1 is considered high injection. If the injection ratio is greater than 1, i.e., under high injection conditions, the majority carrier concentration will change, and the test actually captures the recombination of majority carriers. However, when it is less than 1, carrier recombination follows linear dynamics, and the test signal is strictly proportional to the carrier concentration.

[0065] For sample rods with very high resistivity, special attention must be paid to controlling the injection ratio. This is because the photoconductive signal is often very large at this point, which can easily lead to an inflated reading of the measured data.

[0066] S2. The obtained photoconductive signal is modulated onto a 10.3 GHz high-frequency carrier wave through capacitive coupling between the sample and the electrode;

[0067] S3. Extract the photoconductive signal; the photoconductive signal can be extracted by detection. The photoconductive signal can be extracted from the sampling resistor or directly from both ends of the sample for modulation.

[0068] S4. Using a 30MHz high-frequency power supply, apply it to both ends of the sample;

[0069] S5. Using a laser with a wavelength of 904nm to irradiate the sample, the high-frequency signal at both ends of the sample is modulated. When light irradiates the sample, non-equilibrium minority carriers are generated in the sample, which increases the conductivity of the sample, decreases the resistance, and reduces the high-frequency voltage value at both ends of the sample, thereby modulating the high-frequency signal at both ends of the sample.

[0070] To improve test results, the following approach is adopted: a variable capacitor is inserted in series in the circuit to improve circuit matching and increase the photoconductivity signal. The variable capacitor is a ceramic trimmer capacitor with a capacitance range of 3pF. The variable capacitor is used to reduce noise, improve the circuit, and increase the photoconductivity signal.

[0071] S6, 4min to stop the illumination; after the illumination stops, the non-equilibrium carriers in the sample decay exponentially, gradually recombine and disappear, so the high-frequency voltage amplitude at both ends of the sample gradually returns to the level when there is no illumination. Diode detection plus capacitor filtering is used to demodulate the high-frequency photoconductive signal.

[0072] S7. Increase the photoconductivity attenuation signal; increase the photoconductivity attenuation signal through a wideband amplifier, the bandwidth of the wideband amplifier is greater than 5MHz.

[0073] S8. The minority carrier lifetime of the sample is measured by the decay curve. The amplified signal is applied to a pulse oscilloscope. With the synchronization signal connected, a curve that decays exponentially can be displayed on the fluorescent screen. The minority carrier lifetime of the sample is measured by this decay curve.

[0074] The initial portion of the decay curve is characterized by rapid decay and should be discarded during measurement. Rapid decay is often caused by surface recombination, which can usually be eliminated by removing non-penetrating light using a silicon filter. Additionally, it is advisable to remove the beginning of the signal amplitude (approximately the first third of the amplitude) before taking the reading.

[0075] Trapping effect: When non-equilibrium charge carriers are present, the number of electrons in certain impurity energy levels of a semiconductor changes, leading to the accumulation of charge carriers. This effect of accumulating non-equilibrium charge carriers is called the trapping effect. Generally, an increase in the number of electrons can be considered as the accumulation of electrons, and a decrease in the number of electrons can be considered as the accumulation of holes. Under normal circumstances, non-equilibrium charge carriers that fall into the trap often take a relatively long time to be gradually released, thus causing the decay rate in the latter half of the decay curve to slow down, the so-called "tail".

[0076] The "flat-top" phenomenon in the attenuation curve can be caused by two factors: First, the high-frequency oscillation voltage is too high. In this case, reducing the output power of the high-frequency oscillator will improve the situation. Second, the flash intensity is too strong. Reducing the flash discharge voltage, adding a silicon filter, or reducing the aperture of the aperture lamp can all correct the waveform.

[0077] The lower limit for measuring minority carrier lifetime using the high-frequency photoconductivity decay method is around ten microseconds (determined by the cutoff time of the light pulse), while the upper limit is several thousand microseconds. Due to the limitation of pulse light intensity, the resistivity of the single crystal rod is generally required to be greater than 10² Ω·cm; too low a resistivity will make the photoconductivity signal too weak to be observed.

[0078] Example 3

[0079] Reference Figs. 1-2 As shown, the present invention provides a minority carrier lifetime detection method, which includes the following steps:

[0080] S1. Prepare the test sample; the test sample is mercury cadmium telluride material, and its appearance must be intact during the test; and the injection ratio of the test sample is less than 1%.

[0081] The injection ratio is ΔV / kV; where ΔV is the signal voltage value measured on the oscilloscope, k is the amplification factor of the preamplifier, and V is the voltmeter reading after the detector. The sample injection ratio is the ratio of non-equilibrium carrier concentration to equilibrium carrier concentration. An injection ratio less than 1 is generally considered low injection, and an injection ratio greater than 1 is considered high injection. If the injection ratio is greater than 1, i.e., under high injection conditions, the majority carrier concentration will change, and the test actually captures the recombination of majority carriers. However, when it is less than 1, carrier recombination follows linear dynamics, and the test signal is strictly proportional to the carrier concentration.

[0082] For sample rods with very high resistivity, special attention must be paid to controlling the injection ratio. This is because the photoconductive signal is often very large at this point, which can easily lead to an inflated reading of the measured data.

[0083] S2. The obtained photoconductive signal is modulated onto a 10.5 GHz high-frequency carrier wave through capacitive coupling between the sample and the electrode.

[0084] S3. Extract the photoconductive signal; the photoconductive signal can be extracted by detection. The photoconductive signal can be extracted from the sampling resistor or directly from both ends of the sample for modulation.

[0085] S4. Using a 35MHz high-frequency power supply, apply it to both ends of the sample;

[0086] S5. Using a laser with a wavelength of 904nm to irradiate the sample, the high-frequency signal at both ends of the sample is modulated. When light irradiates the sample, non-equilibrium minority carriers are generated in the sample, which increases the conductivity of the sample, decreases the resistance, and reduces the high-frequency voltage value at both ends of the sample, thereby modulating the high-frequency signal at both ends of the sample.

[0087] To improve the test results, the following approach was adopted: thermal grease was applied between the sample and the electrode to increase the coupling between them, and a variable capacitor was inserted in series in the circuit to improve the circuit matching and increase the photoconductive signal. The variable capacitor was a ceramic trimmer capacitor with a capacitance range of 30pF. The variable capacitor was used to reduce noise, improve the circuit, and increase the photoconductive signal.

[0088] S6, stop illumination after 5 minutes; after the illumination stops, the non-equilibrium carriers in the sample decay exponentially, gradually recombine and disappear, so the high-frequency voltage amplitude at both ends of the sample gradually returns to the level when there is no illumination. Diode detection plus capacitor filtering is used to demodulate the high-frequency photoconductive signal.

[0089] S7. Increase the photoconductivity attenuation signal; increase the photoconductivity attenuation signal through a wideband amplifier, the bandwidth of the wideband amplifier is greater than 5MHz.

[0090] S8. The minority carrier lifetime of the sample is measured by the decay curve. The amplified signal is applied to a pulse oscilloscope. With the synchronization signal connected, a curve that decays exponentially can be displayed on the fluorescent screen. The minority carrier lifetime of the sample is measured by this decay curve.

[0091] The initial portion of the decay curve is characterized by rapid decay and should be discarded during measurement. Rapid decay is often caused by surface recombination, which can usually be eliminated by removing non-penetrating light using a silicon filter. Additionally, it is advisable to remove the beginning of the signal amplitude (approximately the first third of the amplitude) before taking the reading.

[0092] Trapping effect: When non-equilibrium charge carriers are present, the number of electrons in certain impurity energy levels of a semiconductor changes, leading to the accumulation of charge carriers. This effect of accumulating non-equilibrium charge carriers is called the trapping effect. Generally, an increase in the number of electrons can be considered as the accumulation of electrons, and a decrease in the number of electrons can be considered as the accumulation of holes. Under normal circumstances, non-equilibrium charge carriers that fall into the trap often take a relatively long time to be gradually released, thus causing the decay rate in the latter half of the decay curve to slow down, the so-called "tail".

[0093] The "flat-top" phenomenon in the attenuation curve can be caused by two factors: First, the high-frequency oscillation voltage is too high. In this case, reducing the output power of the high-frequency oscillator will improve the situation. Second, the flash intensity is too strong. Reducing the flash discharge voltage, adding a silicon filter, or reducing the aperture of the aperture lamp can all correct the waveform.

[0094] The lower limit for measuring minority carrier lifetime using the high-frequency photoconductivity decay method is approximately ten microseconds (determined by the cutoff time of the light pulse), while the upper limit is several thousand microseconds. Due to limitations imposed by the intensity of the pulsed light, the resistivity of the single crystal rod is generally required to be greater than 10² Ω·cm; too low a resistivity will result in a photoconductivity signal that is too weak to be observed.

[0095] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for detecting minority carrier lifetime, characterized in that, The method includes the following steps: S1. Prepare test samples; S2. The obtained photoconductive signal is modulated onto a 10-10.5 GHz high-frequency carrier wave through capacitive coupling between the sample and the electrode. S3. Extract the photoconductive signal; S4. Apply a 25-35MHz high-frequency power supply to both ends of the sample. S5. Use a laser with a wavelength of 904nm to irradiate the sample, so that the high-frequency signals at both ends of the sample are modulated. S6, after 3-5 minutes, stop the light exposure; S7. Increase the photoconductive attenuation signal; S8. The minority carrier lifetime of the sample is measured by the decay curve.

2. The minority carrier lifetime detection method according to claim 1, characterized in that, The test sample in S1 is a mercury cadmium telluride material, and its appearance is guaranteed to be intact; and the injection ratio of the test sample is less than 1%.

3. The minority carrier lifetime detection method according to claim 1, characterized in that, In step S3, the photoconductive signal is extracted by detection. The photoconductive signal can be extracted from the sampling resistor or directly extracted from both ends of the sample for modulation.

4. The minority carrier lifetime detection method according to claim 1, characterized in that, In step S5, light is irradiated onto the sample, generating non-equilibrium minority carriers in the sample, which increases the conductivity of the sample, decreases the resistance, and reduces the high-frequency voltage across the sample, thereby modulating the high-frequency signal across the sample.

5. The minority carrier lifetime detection method according to claim 4, characterized in that, In step S5, the following approach is adopted to improve the test results: thermal grease is applied between the sample and the electrode to increase the coupling between them.

6. The minority carrier lifetime detection method according to claim 4, characterized in that, In step S5, the following scheme is adopted to improve the test effect: a variable capacitor is inserted in series in the circuit to improve the circuit matching and increase the photoconductive signal.

7. The minority carrier lifetime detection method according to claim 4, characterized in that, In step S5, the following approach is adopted to improve the test results: thermal grease is applied between the sample and the electrode to increase the coupling between them, and a variable capacitor is connected in series in the circuit to improve the circuit matching and increase the photoconductive signal.

8. A minority carrier lifetime detection method according to any one of claims 5, 6, or 7, characterized in that, The variable capacitor is a ceramic trimmer capacitor with a capacitance range of 3-30pF.

9. The minority carrier lifetime detection method according to claim 1, characterized in that, After the illumination is stopped at S6, the non-equilibrium carriers in the sample decay exponentially, gradually recombine and disappear. Therefore, the high-frequency voltage amplitude at both ends of the sample gradually returns to the level when there is no illumination. Diode detection and capacitor filtering are used to demodulate the high-frequency photoconductive signal.

10. The minority carrier lifetime detection method according to claim 1, characterized in that, In step S7, the photoconductive attenuation signal is amplified by a wideband amplifier, and the bandwidth of the wideband amplifier is greater than 5MHz.

11. The minority carrier lifetime detection method according to claim 1, characterized in that, In step S8, the amplified signal is applied to a pulse oscilloscope, and a synchronization signal is connected to display an exponentially decaying curve on the fluorescent screen. The minority carrier lifetime of the sample is measured through this decay curve.

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