Assessment of surface recombination in mid-wave infrared InAsSb nBn detectors using transient microwave reflectance

Investigation of surface recombination is an important area for infrared detectors as the demand for smaller pixels increases. In this study, we use transient microwave reflectance to characterize the minority carrier lifetime of InAsSb nBn structures under three conditions: As-Grown, blanket Barrier-Etched, and SU-8 Passivated blanket barrier-etched. A qualitative comparison of these three samples shows that the minority carrier lifetime decreases for the Barrier-Etched sample compared to the As-Grown sample, indicating that the minority carrier lifetime is sensitive to changes in the sample surface, specifically the introduction of surface states. We compare these samples quantitatively using a polynomial fit (A−1 + Bn + Cn2). We find for the As-Grown sample A = 1.22 ± 0.45 µs, B = 2.5 ± 0.2 × 10−12 cm3/s, and C = 5.004 ± 4.996 × 10−31 cm6/s, for the Barrier-Etched sample A = 1.17 ± 0.40 µs, B = 9.9 ± 0.2 × 10−12 cm3/s, and C = 9.502 ± 9.498 × 10−30 cm6/s, and for the Passivated sample A = 1.34 ± 0.45 µs, B = 5.3 ± 0.5 × 10−12 cm3/s, and C = 5.500 ± 4.500 × 10−33 cm6/s.