Parameters Extraction From The Dark Current Characteristics Of HgCdTe Infrared Detectors

Mercury cadmium telluride (HgCdTe) infrared detectors are widely used in advanced infrared detector systems operating in 1-3,3-5 and 8-14 μ/m atmospheric windows. Current property of HgCdTe can hardly meet the demand in civilian and military fields. In order to further improve the performance of HgCdTe devices, it is necessary to reduce the dark current of the device. In the quantitative analysis of the I-V characteristics of HgCdTe devices, it is very necessary to analyze the physical mechanism of the formation of dark current, which will greatly affect the parameters of the device performance. The main purpose of this paper is put forward a data processing method of I-V data conversion for the R-V fitting calculation through analytical model for simulation analysis, to extract related parameters and through the development of the use of software to carry on the analysis, and specific contents are as follows:1. RV fitting algorithm can be roughly divided into three parts, namely, data conversion and processing, determination of the initial value, and the overall fitting. This curve-fitting model includes the diffusion, generation-recombination, trap-assisted tunneling, and band-to-band tunneling current as dark current mechanisms. In this paper, the realization process of the algorithm is introduced in detail:In data conversion and processing, we use polynomial fitting to smooth the data; In the determination of the initial value, this paper uses the physical mechanism of dark current to segment the R-V curve, and then uses the Levenberg-Marquardt algorithm to fit curve and extract the initial value of the overall fitting by piecewise; Finally, the multi-variable overall fitting of the R-V curve is using the coordinate rotation method (including one dimensional search method).2. In order to facilitate the processing of test data, this paper uses the RV fitting algorithm to develop for the RV fitting software by VC programming. The software function includes a single set of data fitting, the variable temperature fitting and the variable junction area fitting. By using the RV fitting software, the dark current mechanisms of long wavelength HgCdTe photovoltaic detectors at various temperatures and various junction areas is studied. Through R-V curves fitting calculation of the actual device, this paper has been obtained the dependence of devices parameters on temperature and has been get the basic physical parameters of long wavelength HgCdTe photovoltaic devices, providing the references for improving the performance of the device.