Single- and two-color HgTe/CdTe-superlattice based infrared detectors

The optimal performance of HgTe/CdTe superlattice-based LWIR (8-12 μm cutoff wavelengths) and VLWIR (greater than 12um cutoff wavelength) photovoltaic detectors is assessed theoretically. The electronic band structures and optical absorption spectra are computed with a fourteen-band restricted-basis envelope function Hamiltonian. Auger and radiative lifetimes are computed with these accurate band structures. Vertical carrier mobilities are obtained from a Monte Carlo transport methodology. Photon detectors are modeled by solving current continuity and Poisson's equations. Predictions are compared with those for HgCdTe-alloy based detectors. We find that the superlattice-based two-color detector promise sharp rises in quantum efficiencies near the cutoff wavelengths, reflecting the quasi-2-dimensional nature of their density of states.