Analyses On Dark Current Components Of Infrared Detector And Its Mechanism Research

Infrared detector has been widely used in various civilian and military fields because of the device characteristics of strong anti interference ability, high resolution, strong penetrability and can work day and night. Infrared detector possesses the character of expensive and developing period long so that the device simulation has become an important method in optimation and design for device. Dark current has become a limiting factor for the overall performance of infrared detector. In order to improve the performance of infrared detector we must reduce the dark current and improve the signal-noise ratio. But the knowledge of the mechanism of dark current in infrared detector is still not clear. In this paper, by using the numerical simulation and analytic fitting, the dark current mechanism of photovoltaic type infrared detector is studied, which is based on the experimental data and combined the carrier transport model in the semiconductor. We have extracted the dark current components and obtained six characteristic parameters for the electrical performance of the device, which can guide the preparation of infrared dector and promote the development of infrared detection technology. Details are as follows:1. Theoretically study the performance of SAGCM InGaAs/InP APD, and the simulation results of I-V characteristic curves are in good agreement with experimental data. Dark current components at different concentrations of traps in multiplication layer are extracted in the simulations. In addition, the influence of the structural parameters to the punch-voltage and breakdown voltage is discussed.2. The effects of InGaAs absorption layer and n-InP layer on the photo response of InP/InGaAs/InP p-i-n photodiode are numerically investigated. With the thickness of absorption layer increasing, the responsivity firstly increases and then decreases. It was shown that responsivity decreases with increasing thickness of n-InP layer under back-illuminated. We obtained the optimizing thickness of absorption layer and n-InP layer through the analysis of the simulation results.3. Diffusion current, generation recombination current, band to band tunneling current and trap assist tunneling current are the main dark current components in HgCdTe infrared detectors. A simultaneous mode nonlinear curve fitting is used to analysis the I-V characteristic curves of longwave HgCdTe infrared photovoltaic detector at various temperatures. The dependence of dark current components on temperature had been obtained, and the six characteristic parameters versus temperature can be extracted.4. Different annealing time for the performance analysis of mid-wave HgCdTe infrared detectors during analytic fitting. Using this method, the dependence of devices parameters on annealing time had been obtained. The dominated mechanism of dark current at various bias voltages before and after annealing does not change. In addition, the device performances had some influences when the annealing time is equal to at least 24 h.