Correlation between visual defects and increased dark current in large-area Hg1-xCdxTe photodiodes

The Cross-Track Infrared Sounder (CrIS) program [an instrument on the National Polar-Orbiting Operational Environmental Satellite System (NPOESS)] requires photodiodes with spectral cutoffs denoted by short-wavelength infrared [γc(98 K) ∼5.1 µm], midwavelength infrared [γc(98 K) ∼9.1 µm], and long-wavelength infrared (LWIR) [γc(81 K) ∼15.5 µm]. The CrIS instrument also requires large-area (850-µm-diameter) photodiodes with state-of-art performance. Molecular beam epitaxy (MBE) is used to grow n-type short-wavelength infrared, midwavelength infrared, or LWIR Hg1−xCdxTe on latticematched CdZnTe. Detectors with p-type implants 7 µm in diameter are used to constitute the 850-µm-diameter lateral collection diodes (LCDs). The photodiode architecture is the double-layer planar heterostructure architecture.