The red σ2/kT spectral shift in partially disordered semiconductors

Abstract

In connection with some spectral anomalies of the luminescence in III–V semiconductors, we consider here the red spectral shift in partially disordered semiconductors, namely, in heavily doped GaAs and in alloys of InGaP and InGaN. The shift (of the Stokes type) between the Gaussian absorption peak and the quasi-equilibrium low-intensity luminescence peak is equal to σ2/kT, where σ2 is the dispersion of the Gaussian. As this shift is strongly temperature dependent, the temperature-induced blueshift anomaly appears in the temperature dependence of the luminescence peak position in III–V materials. The broadening parameter σ can be derived from spectral measurements. It is determined by the Coulomb-related fluctuations in heavily doped materials or by composition variations in disordered alloys (in bulk materials). In nanostructured materials additional factor of the disordering appears due to roughness of interfaces.