Method for Evaluating the Lifetime of a Short-Wave Infrared Focal Plane Detector with Dark Current as the Degradation Parameter

Abstract

The present invention relates to the field of optoelectronic detection technology, and particularly to a method for evaluating the lifetime of a short-wave infrared focal plane detector with dark current as the degradation quantity, including: dividing a plurality of short-wave infrared focal plane detectors into multiple groups of samples and placing them in a test chamber; performing a charged aging test on the samples under high-temperature conditions in the normal working state; during the charged aging test, continuously collecting multiple frames of image data of the samples at periodic time intervals; increasing the integration time, using the integration time as the abscissa and the gray value of the image data as the ordinate, and fitting to obtain the dark signal; and converting the dark signal into dark current through the circuit gain constant; determining the failure time of the samples based on the change amount of the dark current relative to the initial value to obtain the failure lifetime of the samples at high temperature, and establishing an adaptive acceleration model to calculate the service life of the samples at the normal working temperature. The present invention can measure the dark current of short-wave infrared devices in batches, with accurate measurement results and low cost.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic detection technology, and in particular to a method for evaluating the lifetime of a short-wave infrared focal plane detector with dark current as the degradation quantity. Background Art

[0002] Short-wave infrared focal plane detectors have high detection performance and are widely used in fields such as space remote sensing, low-light-level night vision, medical diagnosis, and industrial inspection. The service life of optoelectronic detectors is long and the stability is good. To discover the degradation law of devices during long-term use in a short time, it is necessary to use the method of accelerated aging experiments to study the performance evolution characteristics of devices over a long time. Accelerated aging is to change the stress level without changing the failure mechanism, thereby shortening the time required for the experiment, improving efficiency, and reducing costs.

[0003] However, traditional acceleration models often assume that the acceleration parameters are fixed and do not consider the fact that these parameters will change dynamically with environmental conditions. Especially in scenarios with a wide working temperature range or large temperature fluctuations, the assumption of a fixed model cannot accurately capture the true degradation process of the device, resulting in an increase in the error of life prediction.

[0004] When traditional infrared focal plane detectors perform dark current tests, they usually choose the method of direct measurement or using a blind cold screen. However, the test conditions of direct measurement are difficult to control and the test result accuracy is low. With the development of short-wave infrared technology and the improvement of application requirements, the performance requirements for detectors are also getting higher and higher. The traditional test methods cannot meet the needs of high-precision tests. And testing under blind cold screen conditions requires changing the component structure, with a long test cycle, low test efficiency, complex operation for packaged devices, and is not suitable for batch testing. Summary of the Invention

[0005] (I) Technical Problems to be Solved

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a method for evaluating the lifetime of a short-wave infrared focal plane detector with dark current as the degradation quantity, which solves the technical problem that the assumption of a fixed acceleration parameter model cannot accurately capture the true degradation process of the device.

[0007] (II) Technical Solutions

[0008] To achieve the above object, the main technical solutions adopted by the present invention include:

[0009] An embodiment of the present invention provides a method for evaluating the lifetime of a short-wave infrared focal plane detector with dark current as the degradation quantity, including the following steps:

[0010] Divide multiple short-wave infrared focal plane detectors into multiple groups of samples and place them in a test chamber;

[0011] Conduct the charged aging test of the sample under high-temperature conditions in the normal working state;

[0012] During the charged aging test, continuously collect multiple frames of image data of the sample at periodic time intervals; increase the integration time, use the integration time as the abscissa, and the gray value of the image data as the ordinate to fit and obtain the dark signal; and convert the dark signal into dark current through the circuit gain constant;

[0013] Judge the failure time of the sample based on the change amount of the dark current relative to the initial value to obtain the failure life of the sample at high temperature, and establish an adaptive acceleration model to calculate the service life of the sample at the normal working temperature.

[0014] Optionally, the test chamber is a dark box with electromagnetic shielding on the box body;

[0015] The temperature of the test chamber is adjustable and can be set to be adjusted according to multiple temperature ranges, and each temperature range is divided into multiple groups of temperature gradients.

[0016] Optionally, during the charged aging test, collect F frames of image data corresponding to each integration value, and F>100; calculate the average gray value output within the effective pixels of the F frames of image data as the ordinate for fitting the dark signal; use the integration time as the abscissa, and fit a straight line to the scatter plot of the obtained average gray values by the least squares method, and the slope of the straight line is used as the dark signal of the sample per unit time.

[0017] Optionally, convert the dark signal into dark current through the circuit gain constant, and the conversion formula is:

[0018]

[0019] where, is the dark current corresponding to the slope, with the unit of DN / s; K is the circuit gain constant, with the unit of ; is equal to Coulomb.

[0020] Optionally, when the change of the dark current value relative to the initial value reaches 30%, and the time when more than 50% of the devices in a group of samples reach failure is the failure life.

[0021] Optionally, establish an adaptive acceleration model to calculate the service life of the sample at the normal working temperature, which is completed using the Arrhenius model, and the Arrhenius equation is expressed as:

[0022]

[0023] where, M is the degradation amount, that is, the change amount of the dark current; A is the frequency factor; is the activation energy in eV; K B is the Boltzmann constant with a value of ; T is the Kelvin temperature in K.

[0024] Optionally, the degradation amount M is calculated as follows:

[0025] Let the degradation parameter value at the initial state of the product be M1, corresponding to the time t1, and the degradation parameter value at the device failure be M2, corresponding to the time t2; the temperature is known, and the cumulative degradation amount from t1 to t2 is:

[0026] ;

[0027] The life L of the device is the difference between t2 and t1, that is: .

[0028] Optionally, the acceleration coefficient in the adaptive acceleration model is:

[0029] ;

[0030] The adaptive acceleration model can adjust the degradation rate according to the actual use temperature change by introducing the temperature-dependent activation energy and frequency factor:

[0031] ;

[0032] where α is the activation energy correction coefficient; β is the frequency factor, that is, the temperature sensitivity coefficient; is the reference temperature selected in the experiment, and the activation energy at the reference temperature is , and the frequency factor at the reference temperature is , and T is the current temperature.

[0033] Optionally, based on the data obtained from the charged aging test in a temperature range, a rectangular coordinate system is established with the reciprocal of temperature and the logarithm of life as the X-axis and Y-axis respectively, and fitted into a straight line; the experimental activation energy of the sample is calculated from the slope of the straight line, and the frequency factor is calculated from the intercept of the straight line; the experimental activation energy and frequency factor are fitted through the data obtained from the charged aging tests of multiple groups of samples in different temperature ranges to determine the activation energy correction coefficient α and the temperature sensitivity coefficient β;

[0034] The activation energy adopts a linear correction coefficient and is calculated through the following expression:

[0035] ;

[0036] The temperature sensitivity coefficient β is calculated through the following expression:

[0037] .

[0038] (III) Beneficial effects

[0039] The beneficial effects of the present invention are as follows: The method for evaluating the lifespan of a short-wave infrared focal plane detector with dark current as the degradation quantity of the present invention can improve the test accuracy, has high detection efficiency, is applicable to different test conditions, and can accurately evaluate the reliability of the device.

[0040] In a preferred embodiment, the method for evaluating the lifespan of a short-wave infrared focal plane detector with dark current as the degradation quantity of the present invention can dynamically adjust the acceleration factor or the degradation rate model according to the actual operating state of the device under different working conditions, thereby making the lifespan evaluation more accurate. This method is particularly applicable to devices used in a changing environment. Since the adaptive acceleration model can dynamically adjust the model parameters for each temperature range, the calculation result of the cumulative damage can be closer to the actual degradation process of the device. Brief Description of the Drawings

[0041] Figure 1 For Figure 1 is a schematic diagram of the high-temperature accelerated aging test structure of the short-wave infrared focal plane detector in the embodiment of the present invention;

[0042] Figure 2 is a flowchart of a method for evaluating the lifespan of a short-wave infrared focal plane detector with dark current as the degradation quantity in the embodiment of the present invention;

[0043] Figure 3 is a linear relationship curve between the average dark field gray value and the integration time in the embodiment of the present invention;

[0044] Figure 4 is a flowchart of the device lifespan evaluation based on the adaptive acceleration model in the actual lifespan test in the embodiment of the present invention. Detailed Embodiments

[0045] In order to better explain the present invention for easy understanding, the present invention will be described in detail below with reference to the drawings through specific embodiments.

[0046] A method for evaluating the lifespan of a short-wave infrared focal plane detector with dark current as the degradation quantity proposed in the embodiment of the present invention can batch measure the dark current of short-wave infrared devices, with accurate measurement results and low cost. It can monitor the charged aging state of the device under test and study the degradation law during the long-term use of the device. It provides effective data for subsequent analysis of the performance parameters of the device and better development and application.

[0047] To better understand the above technical solutions, the exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more clear and thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0048] Figure 1 It is a schematic diagram of the high-temperature accelerated aging test structure of the short-wave infrared focal plane detector in the embodiment of the present invention. The device is placed in a dark box, a group of devices are connected in parallel, the dark box is placed in a high and low temperature box, and it is powered by an external DC power supply; the device outputs an image through a signal line, and the collected data is processed and stored by a computer.

[0049] Figure 2 It is a flowchart of a method for evaluating the lifetime of a short-wave infrared focal plane detector with dark current as the degradation quantity in the embodiment of the present invention. The embodiment of the present invention provides a method for evaluating the lifetime of a short-wave infrared focal plane detector with dark current as the degradation quantity, including the following steps:

[0050] S1: Divide multiple short-wave infrared focal plane detectors into multiple groups of samples and place them in a test chamber.

[0051] In this embodiment, 4 temperature intervals are set at the limit temperature of the photodetector, and there are 5 temperature gradients in each interval, which are 80°C, 85°C, 90°C, 95°C, 100°C; 120°C, 125°C, 130°C, 135°C, 140°C; 160°C, 165°C, 170°C, 175°C, 180°C; 200°C, 205°C, 210°C, 215°C, 220°C. 5 detector samples are taken as a group and connected in parallel and placed in a dark box. Apply a specified power supply voltage to the device to make the device work normally, and test and record the initial value of the dark current of the device at room temperature of 25°C.

[0052] S2: Conduct a charged aging test on the samples under high-temperature conditions in the normal working state.

[0053] During implementation, the test chamber is a dark box with electromagnetic shielding on the box body. The temperature of the test chamber is adjustable and can be set to be adjusted according to multiple temperature intervals, and each temperature interval is divided into multiple groups of temperature gradients.

[0054] In this embodiment, adjust the high and low temperature and humidity test chamber to make the temperature of the device's TEC temperature control module reach the set temperature value, and conduct a test after stabilizing for half an hour. The temperature error is within . All 5 groups of humidity are set to 55%RH at room temperature to avoid the influence of humidity stress on the test, and thus the high-temperature charged aging of the detector is carried out.

[0055] S3: During the charged aging test, continuously collect multiple frames of image data of the sample at periodic time intervals (completed through an image acquisition device and image acquisition software). In implementation, during the charged aging test, collect F frames of image data corresponding to each integration value, and F > 100.

[0056] S4: Increase the integration time, use the integration time as the abscissa, and use the gray value of the image data as the ordinate to fit and obtain the dark signal.

[0057] In implementation, calculate the average gray value output within the effective pixels of the F frames of image data as the ordinate for fitting the dark signal; use the integration time as the abscissa, and fit a straight line by the least squares method for the scatter plot of the obtained average gray values. The slope of the straight line is used as the dark signal of the sample per unit time.

[0058] S5: Convert the dark signal into dark current through the circuit gain constant.

[0059] Such as Figure 3 For the linear relationship curve between the average gray value of the dark field and the exposure time, with the integration time as the abscissa and the output signal (average gray value) as the ordinate, a straight line is fitted by the least squares method for the scatter plot given by the test data. The slope of the straight line is the dark signal per unit time (DN / s) of the device. The circuit gain constant is calculated from the photon transfer curve measured under the condition of light illumination for the device, and the unit is . Convert the dark signal into dark current through the circuit gain constant.

[0060] Convert the dark signal into dark current through the circuit gain constant, and the conversion formula is:

[0061]

[0062] Among them, is the dark current corresponding to the slope, and the unit is DN / s; K is the circuit gain constant, and the unit is e- / DN; is equal to coulomb. Thus, convert the unit of the dark current into amperes (A).

[0063] S6: Determine the failure time of the sample based on the change amount of the dark current relative to the initial value to obtain the failure life of the sample at high temperature, and establish an adaptive acceleration model to calculate the service life of the sample at normal operating temperature.

[0064] During implementation, the temperature of the test chamber is reduced to the normal temperature of 25°C every 240 h. After stabilization, the dark current is measured and data is recorded to determine whether there is a failure in this group of devices, and the failure time is recorded. The criterion for device failure determination is that the dark current value changes by 30% relative to the initial value. The time when more than 50% (for example, more than 3) of the devices in a group reach failure is the test life (failure life).

[0065] Through the above steps, the dark current of short-wave infrared devices can be measured in batches with accurate measurement results and low cost. The charged aging state of the device under test can be monitored, and the degradation law during the long-term use of the device can be studied. It provides effective data for subsequent analysis of the performance parameters of the device and better development and application.

[0066] During implementation, an adaptive acceleration model is established to calculate the service life of this sample at normal operating temperature, which is completed using the Arrhenius model. The Arrhenius equation is expressed as:

[0067] ;

[0068] where M is the degradation amount, that is, the change amount of the dark current; A is the frequency factor; is the activation energy, with the unit of eV; K B is the Boltzmann constant, with a value of ; T is the Kelvin temperature, with the unit of K.

[0069] Among them, the calculation method of the degradation amount M is as follows:

[0070] Assume that the degradation parameter value at the initial state of the product is M1, corresponding to the time t1, and the degradation parameter value when the device fails is M2, corresponding to the time t2; the temperature is known, and the cumulative degradation amount from t1 to t2 is:

[0071] ;

[0072] The life L of the device is the difference between t2 and t1, that is: .

[0073] Assume that the device operates at different temperatures T1 and T2, and after time t1 and t2 respectively, the degradation amounts of the dark current are the same. The acceleration coefficient (acceleration factor) can be deduced. That is, the acceleration coefficient in the adaptive acceleration model is:

[0074] ;

[0075] During implementation, based on the data obtained from the electrified aging test within a temperature range, a rectangular coordinate system is established with the reciprocal of temperature and the logarithm of life as the X-axis and Y-axis respectively, and fitted into a straight line. The experimental activation energy of the sample is calculated from the slope of the straight line, and the frequency factor is calculated from the intercept of the straight line. The adaptive acceleration model enables the model to adjust the degradation behavior according to the temperature change during actual use by introducing temperature-dependent activation energy and frequency factor. The experimental activation energy and frequency factor are determined by fitting the data obtained from the electrified aging tests of samples in multiple different temperature ranges (4 groups are used in this embodiment), and the activation energy correction coefficient α and the temperature sensitivity coefficient β are determined;

[0076] The activation energy adopts a linear correction coefficient and is calculated through the following expression:

[0077] ;

[0078] The temperature sensitivity coefficient β is calculated through the following expression:

[0079] .

[0080] is the reference temperature selected in the experiment, and the activation energy at the reference temperature is , and the frequency factor at the reference temperature is , and T is the current temperature. Thus, the adaptive acceleration model is established. During implementation, the adaptive acceleration model enables the model to adjust the degradation rate according to the actual use temperature change by introducing temperature-dependent activation energy and frequency factor:

[0081] ;

[0082] where α is the activation energy correction coefficient; β is the frequency factor, that is, the temperature sensitivity coefficient; is the reference temperature selected in the experiment, and the activation energy at the reference temperature is , and the frequency factor at the reference temperature is , and T is the current temperature.

[0083] The dark current at which the detector fails at the normal working temperature is the same as the dark current value at which it fails at high temperature. By substituting the experimental activation energy, Kelvin temperature, and the failure life at high temperature, the service life of the device at the normal working temperature can be predicted. In actual prediction, the degradation rate and life prediction will be affected by many uncertain factors (such as experimental errors, environmental fluctuations, material changes, etc.). Through the Bayesian analysis method, based on the uncertainty of the dark current degradation rate test, the life prediction is repeatedly calculated to generate the probability distribution of life, thereby determining the 95% confidence interval.

[0084] Figure 4It is a flowchart for device life evaluation based on an adaptive acceleration model in actual life tests. When actually predicting the device life, the monitored environmental and performance data are fed back into the model. When the degradation rates of temperature or dark current do not match the current model, the parameters of the model are dynamically adjusted to better fit the current state. This mechanism combines real-time data collection and model adaptive adjustment to predict the remaining life of the device. The monitored degradation data can also be used to dynamically optimize the activation energy correction coefficient α and the temperature sensitivity coefficient β, thereby improving the adaptive acceleration model.

[0085] In summary, the life evaluation method for short-wave infrared focal plane detectors with dark current as the degradation quantity in the embodiments of the present invention can batch measure the dark current of short-wave infrared devices, with accurate measurement results and low costs. It can monitor the charged aging state of the device under test and study the degradation law during the long-term use of the device. It provides effective data for subsequent analysis of the device's performance parameters and better development and application. The adaptive acceleration model can be adjusted in real time, especially suitable for devices operating in a dynamic temperature environment, and can more accurately reflect the actual degradation situation. The model can quickly respond when the stress fluctuates, dynamically adjust the life prediction result, and avoid overly idealistic assumptions. By continuously monitoring historical data, the adaptive acceleration model can optimize its internal parameters, and over time, the life prediction will be more accurate. Through uncertainty evaluation, this method can quantify and correct the reliability of the predicted life results and model parameters, enhancing the credibility of the model.

[0086] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0087] In the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium; it can be the internal connection of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0088] In the present invention, unless otherwise clearly specified or limited, when a first feature is "on" or "under" a second feature, it may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, when the first feature is "above", "over" and "on top of" the second feature, it may be that the first feature is directly above or obliquely above the second feature, or it merely means that the horizontal height of the first feature is higher than that of the second feature. When the first feature is "under", "below" and "beneath" the second feature, it may be that the first feature is directly below or obliquely below the second feature, or it merely means that the horizontal height of the first feature is lower than that of the second feature.

[0089] In the description of this specification, the descriptions of terms such as "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples", etc., mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0090] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for evaluating the lifespan of a short-wave infrared focal plane detector with dark current as the degradation quantity, characterized in that, It includes the following steps: Divide multiple short-wave infrared focal plane detectors into multiple groups of samples and place them in a test chamber; Conduct a charged aging test on the samples under high-temperature conditions in the normal working state; During the charged aging test, continuously collect multiple frames of image data of the samples at periodic time intervals; Increase the integration time, use the integration time as the abscissa, and the gray value of the image data as the ordinate to fit and obtain the dark signal; and convert the dark signal into dark current through the circuit gain constant; Judge the failure time of the samples based on the change amount of the dark current relative to the initial value to obtain the failure life of the samples at high temperature, and establish an adaptive acceleration model to calculate the service life of the samples at the normal working temperature.

2. The method for evaluating the life of a short-wave infrared focal plane detector with dark current as the degradation amount according to claim 1, characterized in that: The test chamber is a dark box with electromagnetic shielding on the box body; The temperature of the test chamber is adjustable and can be set to be adjusted according to multiple temperature ranges, and each temperature range is divided into multiple groups of temperature gradients.

3. The method for evaluating the life of a short-wave infrared focal plane detector with dark current as the degradation amount according to claim 1, characterized in that: During the charged aging test, collect F frames of image data corresponding to each integration value, and F>100; calculate the average gray value output within the effective pixels of the F frames of image data as the ordinate for fitting the dark signal; use the integration time as the abscissa, and fit a straight line for the scatter plot of the obtained average gray values by the least squares method, and the slope of the straight line is used as the dark signal of the sample per unit time.

4. The method for evaluating the lifetime of a short-wave infrared focal plane detector using dark current as the degradation quantity according to claim 1, characterized in that: The conversion of the dark signal into dark current through the circuit gain constant, and the conversion formula is: ； Among them, is the dark current obtained corresponding to the slope, with the unit of DN / s; K is the circuit gain constant, with the unit of ; equals coulomb.

5. The method for evaluating the lifespan of a short-wave infrared focal plane detector with dark current as the degradation quantity according to any one of claims 1 to 4, characterized in that: When the dark current value changes by 30% relative to the initial value, and the time when more than 50% of the devices in a group of samples reach failure is the failure life.

6. The method for evaluating the lifespan of a short-wave infrared focal plane detector using dark current as the degradation quantity as described in claim 5, wherein The establishment of the adaptive acceleration model to calculate the service life of the sample at the normal working temperature is completed using the Arrhenius model, and the Arrhenius equation is expressed as: ； Among them, M is the degradation amount, that is, the dark current change amount; A is the frequency factor; is the activation energy, with the unit of eV; K B is the Boltzmann constant, with a value of ; T is the Kelvin temperature, with the unit of K.

7. The method for evaluating the lifespan of a short-wave infrared focal plane detector with dark current as the degradation quantity according to claim 6, characterized in that, The calculation method of the degradation amount M is as follows: Assume that the degradation parameter value at the initial state of the product is M1, and the corresponding time is t1. When the device fails, the degradation parameter value is M2, and the corresponding time is t2; the temperature is known, and the cumulative degradation amount from t1 to t2 is: ； The lifetime L of the device is the difference between t2 and t1, that is: .

8. The method for evaluating the lifetime of a short-wave infrared focal plane detector with dark current as the degradation quantity according to claim 7, wherein The acceleration coefficient in the adaptive acceleration model is: ； The adaptive acceleration model enables the model to adjust the degradation rate according to the actual use temperature change by introducing a temperature-dependent activation energy and frequency factor: ； Among them, α is the activation energy correction coefficient; β is the frequency factor, i.e., the temperature sensitivity coefficient; is the reference temperature selected in the experiment, and the activation energy at the reference temperature is , and the frequency factor at the reference temperature is , and T is the current temperature.

9. The method for evaluating the lifespan of a short-wave infrared focal plane detector using dark current as the degradation quantity according to claim 8, wherein Based on the data obtained from the charged aging test in a temperature range, establish a rectangular coordinate system with the reciprocal of temperature and the logarithm of life as the X-axis and Y-axis respectively, and fit it into a straight line; calculate the experimental activation energy of the sample from the slope of the straight line, and calculate the frequency factor from the intercept of the straight line; determine the activation energy correction coefficient α and the temperature sensitivity coefficient β by fitting the experimental activation energy and frequency factor with the data obtained from the charged aging tests of multiple groups of samples in different temperature ranges; The activation energy adopts a linear correction coefficient and is calculated through the following expression: ； The temperature sensitivity coefficient β is calculated through the following expression: 。

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