Temperature-dependent ultrafast hot carrier dynamics in the dilute bismide alloy GaSb1−xBix (x ≾ 0.4%)

Abstract

We report temperature-dependent hot carrier dynamics in liquid-phase epitaxy-grown GaSb1−xBix epilayers with dilute amounts of Bi (x ≾ 0.4%). Degenerate pump–probe (λ = 800 nm) transient reflectivity (PPTR) was used to investigate the carrier dynamics in the epilayers. The PPTR signal consists of two transient processes (fast and slow) at all temperatures for all epilayers. The fast, hot carrier relaxation time, which is attributed to the combined effect of intervalley scattering and thermalization of carriers below cryogenic temperatures (<100 K), is observed to increase with an increase in temperature (≈0.8–2 ps at 6.6 K and ≈4–5 ps at 300 K). However, at higher temperatures (>100 K), the interband CHSH-Auger recombination process affects the band-to-band recombination, leading to an increase in the slower decay time. The findings offer crucial insights for optimizing GaSbBi for hot carrier solar cell applications.