Extraction of Material Properties and Defect Levels and Densities from Electrical Measurements

Knowledge of defects and how they affect an infrared detector material is important to understand the performance of the infrared detector. Current-voltage (I-V) Measurements were made on various LWIR and VWLIR HgCdTe photodiodes as a function of temperature. The I-Vs were fitted to a model to obtain defect densities in the detector material. Detector I-Vs were also measured to obtain electrical information. The diffusion current was separated from the total current from the measured I-Vs. Minority carrier lifetime vs. temperature and minority carrier mobility vs. temperature was extracted from the diffusion current. The minority carrier lifetime vs. temperature was fitted to a model to obtain defect energy levels. Measurements on detectors of varying area allowed for the separation of surface and bulk currents. The R0A vs. detector area was measured to obtain a surface recombination velocity. Noise as a function of frequency was measured and correlated with the defect densities obtained from the measured I-Vs.