Molecular beam epitaxy of HgCdTe for infrared focal plane arrays

Middle wavelength IR photovoltaic detectors were fabricated with HgCdTe epilayers grown by molecular beam epitaxy. The epilayers were grown on a slightly misoriented (111) B CdZnTe substrate and were twin free. Epitaxy was carried out with substrate rotation and the wavelength uniformity achieved on a 20 X 20 mm2 wafer was 0.80%. A planar photovoltaic technology was used to produce the IR photodiodes and the junction formation was obtained by ion implantation. Linear array photodiodes and 128 X 128 2D-arrays interconnected with a CCD readout circuit were achieved. RoA product values of 4.7 105 ohm cm2 were measured on diodes with a 4.7 micron cutoff wavelength at 77 K. The good homogeneity of the layer is reflected by the low value, 4.4%, of the standard deviation on the short circuit current histogram of the 2D-array.