Unraveling Band‐Tail Effects on Temperature‐Dependent Emission in GaAsBi via Photoluminescence

An innovative dual‐spectroscopy approach resolves the debate over GaAsBi's emission temperature sensitivity. By combining temperature‐dependent photoluminescence and transmission spectroscopy, the method decouples the contributions of band‐tail states from the intrinsic band‐edge behavior. This clarifies the origin of conflicting thermal coefficients and provides essential guidance for the design of stable GaAsBi‐based devices. Abstract The effect of Bi on the emission temperature sensitivity of GaAsBi remains a topic of debate, which hinders the design of optoelectronic devices. Band‐tail states, which are critical for GaAsBi performance, are suspected to drive the discrepancy, but their effect remains unclear. This work resolves the key debate using an innovative dual‐spectroscopy approach that combines temperature‐dependent photoluminescence (PL) and transmission spectroscopy to decouple the contributions of band‐tail states from intrinsic band‐edge behavior. For GaAs1‐xBix (x = 0.033, 0.048), the energy‐temperature coefficients derived from transmission are composition‐independent, while those derived from PL decrease by ≈40% with higher Bi content. This apparent contradiction originates from the thermalized carrier redistribution between the valence band and band‐tail states at elevated temperatures and the intrinsic band‐edge thermal sensitivity in the transmission spectra. The dual‐spectroscopy approach is proven to be an effective method for clarifying the effects of band‐tail states on the thermal sensitivity, and provides valuable guidance for the design of stable GaAsBi optoelectronic devices. An innovative dual-spectroscopy approach resolves the debate over GaAsBi's emission temperature sensitivity. By combining temperature-dependent photoluminescence and transmission spectroscopy, the method decouples the contributions of band-tail states from the intrinsic band-edge behavior. This clarifies the origin of conflicting thermal coefficients and provides essential guidance for the design of stable GaAsBi-based devices. Abstract The effect of Bi on the emission temperature sensitivity of GaAsBi remains a topic of debate, which hinders the design of optoelectronic devices. Band-tail states, which are critical for GaAsBi performance, are suspected to drive the discrepancy, but their effect remains unclear. This work resolves the key debate using an innovative dual-spectroscopy approach that combines temperature-dependent photoluminescence (PL) and transmission spectroscopy to decouple the contributions of band-tail states from intrinsic band-edge behavior. For GaAs 1- x Bi x ( x = 0.033, 0.048), the energy-temperature coefficients derived from transmission are composition-independent, while those derived from PL decrease by ≈40% with higher Bi content. This apparent contradiction originates from the thermalized carrier redistribution between the valence band and band-tail states at elevated temperatures and the intrinsic band-edge thermal sensitivity in the transmission spectra. The dual-spectroscopy approach is proven to be an effective method for clarifying the effects of band-tail states on the thermal sensitivity, and provides valuable guidance for the design of stable GaAsBi optoelectronic devices. Advanced Science, EarlyView.