Contactless measurement of minority carrier lifetime and background carrier concentration in unintentionally doped GaAsSb for short-wave infrared detection

Abstract

Transient microwave reflectance (TMR) measurements are used to characterize the minority carrier lifetime and background carrier concentration of unintentionally doped (UID) Ga0.5As0.5Sb lattice matched to InP at room temperature. A p-i-n sample is measured, with UID GaAsSb as the intrinsic absorber. In addition to UID GaAsSb, we determine the minority carrier lifetime and doping concentration of a buried doped n+ GaAsSb layer. The measured minority carrier lifetimes are 20.5 ± 6.3 and 0.56 ± 0.23 µs for UID and doped GaAsSb, respectively, and comparable to that of lattice matched InGaAs. For both layers, the dominant recombination mechanisms are Shockley–Read–Hall (SRH) and Auger mechanisms. The measured background carrier concentrations are in good agreement with capacitance–voltage (C–V) measurements, with n0 = 1.81 ± 0.61 × 1015 cm−3 by TMR and n0 = 1.5 × 1015 cm−3 by C–V measurements for the UID layer and ND = 5.18 ± 1.42 × 1017 cm−3 by TMR and ND = 3–4 × 1017 cm−3 by C–V measurements for the doped layer. An absorber-only structure was also measured, and we report the SRH lifetime, radiative coefficient, and Auger coefficient for this sample.