Hgcdtehdvip Detectors And Fpas For Strategic Applications

Detector characteristics of Cu- and Au-doped High Density Vertically Integrated Photodiode (HDVIP) detectors as well as Cu-doped HDVIP Focal Plane Arrays (FPAs) are presented in this paper. Individual photodiodes in test bars were examined by measuring I-V curves and the associated resistance-area (RA) product as a function of temperature. The Au-doped MWIR [lambda(c)(78 K) = 5 mum] HDVIP detectors RoA performance was within a factor of two or three of theoretical. Noise as a function of frequency has been measured on Au-doped MWIR HgCdTe HDVIP diodes at several temperatures under dark and illuminated conditions. Low-frequency noise performance of the Au-doped MWIR diode in the various environments is characterized by the ratio alpha of the noise current spectral density at I Hz: to the value of the diode current. For photocurrent at 140 K, alpha(PHOTO) = 1.8 x 10(-5). The value Of alpha(PHOTO) is the same at both zero bias and 100 mV reverse bias. At 160 K, alpha(PHOTO) is slightly lower but still in the low 10(-5) range. Excess low-frequency noise measured at 140 K and 100 mV reverse bias in the dark has alpha(DARK) = 1.4 x 10(-5). At 160 K and 100 mV reverse bias, alpha(DARK) is in the mid 10(-5) range. At 140 K, the dark current at 8.2 V reverse bias was equal to the photocurrent at 100 mV reverse bias and close to the photocurrent at zero bias. alpha(DARK) = 1.85x10(-3) at -8.2 V. This ratio is two orders of magnitude greater than alpha(PHOTO). At 8.2 V reverse bias, the current was amplified by avalanche processes. Similar results were obtained on the Au-doped diode at 160 K. Diffusion current dominates dark current at 100 mV reverse bias at T = 185 K and T = 220 K. The ratio, alpha(DARK) similar to alpha(PHOTO) in the low to mid 10(-5) range, i.e. dark diffusion current generates excess low frequency noise in the same manner as photocurrent. In addition, 256 x 256 Cu-doped detector arrays were fabricated. Initial measurements had seven out of ten FPAs having operabilities greater than 99.45% with the best 256 x 256 array having only two inoperable pixels.