II-VI infrared superlattices

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Abstract
Superlattice materials systems have recently been proposed to overcome the inherent problems of large tunnel and dark currents that limit the operation of infrared detectors at longer wavelengths (≥10 μm). We have utilized the envelope function approximation and a simple two‐band Kane model to calculate the dependence of cutoff wavelength and effective mass on specific layer thicknesses for the HgTe‐CdTe materials system. Infrared absorption coefficient calculations have been carried out on this system (with Eg =0.1 eV) and compared with both HgTe and 0.1‐eV HgCdTe alloy. Infrared device performance for various proposed superlattice systems is predicted from a consideration of effective mass and absorption coefficient values. Superlattice systems involving materials with the inverted gray tin band structure are seen to offer the greatest potential for future infrared devices.