Temperature dependence of the fundamental direct transitions of bulk Ge and two Ge/SiGe multiple-quantum-well structures

Abstract

From a detailed line-shape fit to piezoreflectance spectra, we have evaluated the temperature dependence (19T420 K) of the energies [E(T)] and broadening parameters [\ensuremath{\Gamma}(T)] of the fundamental direct transitions in bulk Ge and two narrow Ge/GeSi multiple-quantum-well structures. The experimental broadening parameters are compared with theoretical expressions. No significant dimensionality dependence of \ensuremath{\Gamma}(T) was observed, in contrast to polar systems. On the other hand, in agreement with polar materials, E(T) of the microstructures was found to be the same as the constituent bulk well material.