Optical and electrical properties of narrow-bandgap infrared W-structure superlattices incorporating AlAs/AlSb/AlAs barrier layers.

Optical and electrical properties of nBn photodetectors using InAs/AlAs/AlSb/AlAs/InAs/ InAs0.61Sb0.39W-structure superlattice (W-SL) absorbers are reported. Minority carrier lifetimes of 500 ± 50 ns and 400 ± 30 ns, and Auger coefficients of 2.1 × 10-26 cm6/s and 1.6 × 10-25 cm6/s, for samples with bandgap energies of 5.3 lm (W-SL A) and 7.5 lm (W-SL B) are reported at 100 K, respectively. Shockley-Read-Hall defect states are identified at 65 meV and 45 meV above the W-SL valence band edges for W-SLs A and B, respectively. Dark currents are also reported and compared with diffusion currents calculated using the carrier lifetime data, suggesting low vertical heavy hole diffusivity. [ABSTRACT FROM AUTHOR]