Short-wave infrared focal plane detector service life evaluation method with dark current as degradation amount

Abstract

The invention relates to the technical field of photoelectric detection, in particular to a short-wave infrared focal plane detector service life evaluation method with dark current as degradation amount, which comprises the following steps: dividing a plurality of short-wave infrared focal plane detectors into a plurality of groups of samples, and placing the samples in a test box; carrying out an electrified aging test on the sample under a high-temperature condition in a normal working state; in the electrified aging test process, continuously collecting multi-frame image data of the sample according to a periodic time interval; the integral time is increased, the integral time is used as a horizontal coordinate, the gray value of the image data is used as a vertical coordinate, and a dark signal is obtained through fitting; the dark signal is converted into dark current through a circuit gain constant; and judging the failure time of the sample according to the variable quantity of the dark current relative to the initial value to obtain the failure life of the sample at high temperature, and establishing a self-adaptive acceleration model to calculate the service life of the sample at normal working temperature. The dark current of the short-wave infrared device can be measured in batches, the measurement result is accurate, and the cost is low.

Description

Technical Field

[0001] The invention relates to the field of photoelectric detection technology, and in particular to a method for evaluating the life of a short-wave infrared focal plane detector using dark current as a degradation amount. Background Art

[0002] Short-wave infrared focal plane detectors have high detection performance and are widely used in aerospace remote sensing, low-light night vision, medical diagnosis, industrial detection and other fields. Photoelectric detectors have a long service life and good stability. In order to discover the degradation law of devices during long-term use in a short period of time, it is necessary to use accelerated aging experiments to study the long-term performance evolution characteristics of devices. 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 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 operating temperature range or large temperature fluctuations, the assumptions of fixed models cannot accurately capture the true degradation process of the device, resulting in increased errors in life prediction.

[0004] Traditional infrared focal plane detectors usually choose direct measurement or blind cold screen method for dark current testing. However, direct measurement test conditions are difficult to control and the test results are of low accuracy. With the development of short-wave infrared technology and the increase in application demand, the performance requirements for detectors are also getting higher and higher. Traditional testing methods cannot meet the needs of high-precision testing. Testing under blind cold screen conditions requires changing the component structure, has a long test cycle, and has low test efficiency. It is complicated to operate for packaged devices and is not suitable for batch testing. Summary of the invention

[0005] 1. Technical issues to be resolved

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

[0007] (II) Technical solution

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

[0009] The embodiment of the present invention provides a method for evaluating the life of a short-wave infrared focal plane detector using dark current as a degradation amount, comprising the following steps:

[0010] A plurality of short-wave infrared focal plane detectors are divided into a plurality of groups of samples and placed in a test box;

[0011] Conduct electrical aging test on samples under high temperature conditions under normal working conditions;

[0012] During the live aging test, multiple frames of image data of the sample are continuously collected at periodic time intervals; the integration time is increased, and the integration time is used as the horizontal axis, and the gray value of the image data is used as the vertical axis to fit the dark signal; and the dark signal is converted into dark current through the circuit gain constant;

[0013] The failure time of the sample is determined by the change of the dark current relative to the initial value to obtain the failure life of the sample at high temperature, and an adaptive acceleration model is established to calculate the service life of the sample under normal working temperature.

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

[0015] The temperature of the test chamber is adjustable and can be set to multiple temperature intervals, with each temperature interval being divided into multiple groups of temperature gradients for adjustment.

[0016] Optionally, during the live aging test, F frames of image data are collected corresponding to each integral value, and F>100; the grayscale average value output in the effective pixels of the F frame image data is calculated as the vertical coordinate of the fitted dark signal; using the integration time as the horizontal coordinate, the scatter plot of the obtained grayscale average value is fitted to a straight line 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, the dark signal is converted to dark current by the circuit gain constant, and the conversion formula is:

[0018] I d =k d ×K×q

[0019] Among them, k d is the dark current obtained from the corresponding slope, in DN / s; K is the circuit gain constant, in e- / DN; q is equal to 1.6×10 -19 coulomb.

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

[0021] Optionally, an adaptive acceleration model is established to calculate the service life of the sample under normal operating temperature, which is completed using the Arrhenius model. The Arrhenius equation is expressed as:

[0022]

[0023] Among them, M is the degradation amount, that is, the change in dark current; A is the frequency factor; E ais the activation energy, in eV; K B is the Boltzmann constant, which is 8.617x10 -5 eV / K; T is Kelvin temperature, unit is K.

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

[0025] Assume that the degradation parameter value of the product in the initial state is M1, the corresponding time is t1, and the degradation parameter value when the device fails is M2, the corresponding time is t2; the temperature is known, and the cumulative degradation from t1 to t2 is:

[0026]

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

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

[0029]

[0030] The adaptive model introduces temperature-dependent activation energy and frequency factors, allowing the model to adjust the degradation rate according to actual usage temperature changes:

[0031]

[0032] Among them, α is the activation energy correction coefficient; β is the frequency factor, that is, the temperature sensitivity coefficient; T0 is the reference temperature selected in the experiment, and the activation energy at the reference temperature is E a0 ,The frequency factor at the reference temperature is A0, and T is the current temperature.

[0033] Optionally, according to the data obtained from the charged aging test in a temperature range, a rectangular coordinate system is established with the inverse of temperature and the logarithm of life as the X-axis and Y-axis respectively, and a straight line is fitted; 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 the frequency factor are fitted by the data obtained from the charged aging test of multiple groups of samples in different temperature ranges, and the activation energy correction coefficient α and the temperature sensitivity coefficient β are determined;

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

[0035] E a (T) = E a0 +α(T-T0);

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

[0037] A(T)=A0exp(β(T-T0)).

[0038] (III) Beneficial effects

[0039] The beneficial effects of the present invention are as follows: the short-wave infrared focal plane detector life assessment method using dark current as degradation amount can improve test accuracy, has high detection efficiency, is applicable to different test conditions, and can accurately assess the reliability of the device.

[0040] In a preferred embodiment, the short-wave infrared focal plane detector life assessment method using dark current as the degradation amount of the present invention can dynamically adjust the acceleration factor or degradation rate model according to the actual operating state of the device under different working conditions, thereby making the life assessment more accurate. This method is particularly suitable for devices used in a changing environment. Since the adaptive model can dynamically adjust the model parameters for each temperature interval, the calculation result of the accumulated damage can be closer to the actual degradation process of the device. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0042] Figure 2 A flow chart of a method for evaluating the life of a short-wave infrared focal plane detector using dark current as a degradation amount according to an embodiment of the present invention;

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

[0044] Figure 4 The present invention is a flowchart of device life assessment based on an adaptive acceleration model in actual life testing according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

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

[0047] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more 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 is powered by an external DC power supply; the device outputs images through the signal line, and the collected data is processed and stored by a computer.

[0049] Figure 2 The present invention provides a method for evaluating the life of a short-wave infrared focal plane detector using dark current as the degradation amount, comprising the following steps:

[0050] S1: Divide multiple shortwave 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 extreme temperature of the photodetector, and 5 groups of temperature gradients are set in each interval, namely 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. Five detector samples are connected in parallel as a group and placed in a dark box. The specified power supply voltage is applied to the device to make the device work normally, and the initial value of the dark current of the device at room temperature 25°C is tested and recorded.

[0052] S2: Conduct an electrical aging test on the sample under high temperature conditions under normal working conditions.

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

[0054] In this embodiment, the high and low temperature humidity test chamber is adjusted to make the temperature of the device TEC temperature control module reach the set temperature value, and the test is carried out after stabilization for half an hour, and the temperature error is ±0.5°C. The 5 groups of humidity are all set to 55%RH under room temperature conditions to avoid the influence of humidity stress on the test, thereby performing high temperature electrical aging of the detector.

[0055] S3: During the live aging test, multiple frames of image data of the sample are continuously collected at periodic time intervals (completed by image acquisition equipment and image acquisition software). During implementation, during the live aging test, F frames of image data are collected for each integral value, and F>100.

[0056] S4: Increase the integration time, and use the integration time as the horizontal coordinate and the gray value of the image data as the vertical coordinate to obtain the dark signal by fitting.

[0057] During implementation, the grayscale average value output within the effective pixel of the F frame image data is calculated as the ordinate of the fitted dark signal; the integration time is used as the abscissa, and the scatter plot of the obtained grayscale average value is fitted to a straight line by the least squares method, and the slope of the straight line is used as the dark signal of the sample per unit time.

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

[0059] like Figure 3 The linear relationship curve between the average grayscale value of the dark field and the exposure time, with the integration time as the horizontal axis and the output signal (grayscale average value) as the vertical axis, is a straight line fitted by the least squares method from the scatter plot given by the test data. The slope of the straight line is the dark signal per unit time of the device (DN / s). The circuit gain constant is calculated by measuring the photon transfer curve of the device under illumination conditions, and the unit is e- / DN. The dark signal is converted into dark current through the circuit gain constant.

[0060] The dark signal is converted into dark current through the circuit gain constant. The conversion formula is:

[0061] I d =k d ×K×q

[0062] Among them, k d is the dark current obtained from the corresponding slope, in DN / s; K is the circuit gain constant, in e- / DN; q is equal to 1.6×10 -19 Coulomb. From this, the dark current unit is converted into ampere (A).

[0063] S6: The failure time of the sample is determined by the change in the dark current relative to the initial value to obtain the failure life of the sample at high temperature, and an adaptive acceleration model is established to calculate the service life of the sample under normal operating temperature.

[0064] During implementation, the temperature of the test chamber is lowered to 25°C at intervals of 240 hours to stabilize, and then dark current is measured and data is recorded to determine whether there is a failure in the group of devices and record the failure time. The basis for determining device failure 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) devices in a group of devices 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 aging state of the device under test can be monitored, and the degradation law of the device during long-term use can be studied. It provides effective data for subsequent analysis of device performance parameters and better development of applications.

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

[0067]

[0068] Among them, M is the degradation amount, that is, the change in dark current; A is the frequency factor; E a is the activation energy, in eV; K B is the Boltzmann constant, which is 8.617x10 -5 eV / K; T is Kelvin temperature, unit is K.

[0069] The degradation amount M is calculated as follows:

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

[0071]

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

[0073] Assuming that the device works at different temperatures T1 and T2, and the degradation of dark current is the same after time t1 and t2, the acceleration coefficient (acceleration factor) can be derived. That is, the acceleration coefficient in the adaptive acceleration model is:

[0074]

[0075] During implementation, according to the data obtained from the live aging test in a temperature range, a rectangular coordinate system is established with the inverse of temperature and the logarithm of life as the X-axis and Y-axis respectively, and a straight line is fitted; 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 model introduces temperature-dependent activation energy and frequency factors, so that the model can adjust the degradation behavior according to the actual temperature changes. The experimental activation energy and frequency factor are fitted with the data obtained from the live aging test of multiple groups of samples in 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 is calculated using the following expression using a linear correction coefficient:

[0077] E a (T) = E a0 +α(T-T0);

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

[0079] A(T)=A0exp(β(T-T0)).

[0080] T0 is the reference temperature selected in the experiment. The activation energy at the reference temperature is E a0 , the frequency factor at the reference temperature is A0, and T is the current temperature. Thus, an adaptive acceleration model is established. During implementation, the adaptive model introduces temperature-dependent activation energy and frequency factors, so that the model can adjust the degradation rate according to the actual use temperature change:

[0081]

[0082] Among them, α is the activation energy correction coefficient; β is the frequency factor, that is, the temperature sensitivity coefficient; T0 is the reference temperature selected in the experiment, and the activation energy at the reference temperature is E a0 ,The frequency factor at the reference temperature is A0, and T is the current temperature.

[0083] The dark current at which the detector fails at normal operating temperature is the same as the dark current at high temperature. By introducing the experimental activation energy, Kelvin temperature and failure life at high temperature, the service life of the device at normal operating temperature can be predicted. In actual predictions, 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 a probability distribution of the life, thereby determining a 95% confidence interval.

[0084] Figure 4 It is a device life assessment flow chart based on an adaptive acceleration model in actual life testing. When predicting the device life, the real-time monitored environment and performance data are fed back to the model. When the temperature or dark current degradation rate does not match the current model, the model parameters are dynamically adjusted to make it more suitable for the current state. This mechanism combines real-time data acquisition 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 model.

[0085] In summary, a short-wave infrared focal plane detector life assessment method using dark current as degradation quantity in an embodiment of the present invention can measure the dark current of short-wave infrared devices 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 of the device during long-term use can be studied. It provides effective data for subsequent analysis of the performance parameters of the device and better development of applications. The adaptive model can be adjusted in real time, and is particularly suitable for devices working in a dynamic temperature environment, which can more accurately reflect the actual degradation situation. The model can respond quickly to stress fluctuations, dynamically adjust the life prediction results, and avoid overly idealized assumptions. By continuously monitoring historical data, the adaptive model can optimize its internal parameters, and the life prediction will be more accurate over time. Through uncertainty assessment, the method can quantify and correct the reliability of the predicted life results and model parameters, thereby 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 used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0087] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, 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 and limited, when a first feature is “on” or “below” a second feature, it may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, when a first feature is “above”, “above” or “above” a second feature, it may be that the first feature is directly above or obliquely above the second feature, or it may simply mean that the first feature is higher in level than the second feature. When a first feature is “below”, “below” or “below” a second feature, it may be that the first feature is directly below or obliquely below the second feature, or it may simply mean that the first feature is lower in level than the second feature.

[0089] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction 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, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0090] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for evaluating the life of a short-wave infrared focal plane detector using dark current as degradation quantity, characterized in that: The following steps are involved: A plurality of short-wave infrared focal plane detectors are divided into a plurality of groups of samples and placed in a test box; Conduct electrical aging test on samples under high temperature conditions under normal working conditions; During the live aging test, multiple frames of image data of the sample are continuously collected at periodic time intervals; Increasing the integration time, and taking the integration time as the abscissa and the gray value of the image data as the ordinate, the dark signal is obtained by fitting; and the dark signal is converted into a dark current through a circuit gain constant; The failure time of the sample is determined by the change of the dark current relative to the initial value to obtain the failure life of the sample at high temperature, and an adaptive acceleration model is established to calculate the service life of the sample under normal operating temperature.

2. The short-wave infrared focal plane detector life assessment method using dark current as degradation amount as claimed in claim 1, characterized in that: The test box is a dark box with electromagnetic shielding; The temperature of the test box is adjustable and can be set to be adjusted according to multiple temperature intervals, with each temperature interval being divided into multiple groups of temperature gradients for adjustment.

3. The method for evaluating the life of a short-wave infrared focal plane detector using dark current as the degradation amount as claimed in claim 1, characterized in that: During the live aging test, F frames of image data are collected for each integral value, and F>100; the grayscale average value output in the effective pixels of the F frame image data is calculated as the ordinate of the fitted dark signal; the integration time is used as the abscissa, and the scatter plot of the obtained grayscale average value is fitted to a straight line 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 life of a short-wave infrared focal plane detector using dark current as the degradation amount as claimed in claim 1, characterized in that: The dark signal is converted into dark current through the circuit gain constant, and the conversion formula is: I d =k d ×K×q Among them, k d is the dark current obtained from the corresponding slope, in DN / s; K is the circuit gain constant, in e- / DN; q is equal to 1.6×10 -19 coulomb.

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

6. The method for evaluating the life of a short-wave infrared focal plane detector using dark current as the degradation amount as claimed in claim 5, characterized in that: The adaptive acceleration model is established to calculate the service life of the sample under normal working temperature, using the Arrhenius model, and the Arrhenius equation is expressed as: Where M is the degradation amount, that is, the change in dark current; A is the frequency factor; Ea is the activation energy, in eV; K B is the Boltzmann constant, which is 8.617x10- 5 eV / K; T is Kelvin temperature, unit is K.

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

8. The method for evaluating the life of a short-wave infrared focal plane detector using dark current as the degradation amount as claimed in claim 7, characterized in that: The acceleration coefficient in the adaptive acceleration model is: The adaptive model introduces temperature-dependent activation energy and frequency factors, so that the model can adjust the degradation rate according to the actual use temperature changes: Among them, α is the activation energy correction coefficient; β is the frequency factor, that is, the temperature sensitivity coefficient; T0 is the reference temperature selected in the experiment, the activation energy at the reference temperature is Ea0, the frequency factor at the reference temperature is A0, and T is the current temperature.

9. The method for evaluating the life of a short-wave infrared focal plane detector using dark current as the degradation amount as claimed in claim 8, characterized in that: According to the data obtained from the live aging test in a temperature range, a rectangular coordinate system is established with the inverse of temperature and the logarithm of life as the X-axis and Y-axis respectively, and a straight line is fitted; 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 the frequency factor are fitted by the data obtained from the live aging test of multiple groups of samples in different temperature ranges, and the activation energy correction coefficient α and the temperature sensitivity coefficient β are determined; The activation energy is calculated using the following expression using a linear correction coefficient: E a (T)=E a0 +α(T-T0); The temperature sensitivity coefficient β is calculated by the following expression: A(T)=A0exp(β(T-T0)).

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