Analysis of dark current in IR detectors on thinned p-type HgCdTe

A model for the diffusion dark current in MIS IR detectors on thinned bulk p-type HgCdTe is discussed. The model includes trap-assisted tunneling mechanisms in the back-side depletion region as well as the effects of fast surface states. Expressions for the net recombination rate are developed for situations in which trap-assisted tunneling transitions are allowed. Calculations for 12-μm optical cutoff detectors operating at liquid-nitrogen temperature show that the properties of the back side, including surface fixed charge density, depletion region trap density, fast surface-state density, and majority carrier concentration, have a strong influence on the dark current levels of detectors on thin material. It is predicted that typical as-fabricated surface parameters will not result in large dark current densities. Calculations for detectors with surface parameters common to stressed (degraded) back surfaces, however, show dark current densities which would significantly affect detector performance     

Band structure,magneto-transport,and magneto-optical properties of lnAs-Ga1-xlnxSb superlattices

We have theoretically and experimentally investigated the electronic properties of InAs-Ga_1-xIn_xSb superlattices. It is found that a strong repulsion between the El and HI bands in superlattices with thin Ga_1-xIn_xSb layers leads to dispersion relations that closely resemble those in HgTe-CdTe superlattices. Temperature-dependent magneto-transport and magneto-optical measurements on samples with a range of InAs layer thicknesses confirm several of the theoretically predicted consequences, e.g., the coexistence of two electron species in semimetallic superlattices and a very light electron cyctron mass in narrow-gap semiconducting samples. The electron mobility is found to be dominated by interface roughness scattering under nearly all conditions of interest. Implications for this system as an infrared detector material are discussed.