Photoluminescence and photoluminescence excitation spectroscopy of Al0.48In0.52As

Abstract

A detailed study of the photoluminescence (PL) and photoluminescence excitation (PLE) properties of Al0.48In0.52As is presented. A PL linewidth of 13 meV and a Stokes shift of only 9 meV at 4.2 K both indicate that the effect of clustering is minimal in our samples. The Stokes shift is three times lower than the lowest reported in the literature. No shift was observed in the position of the PL peak with changing excitation intensity. Both the PL energy and intensity showed anomalous temperature behavior: The energy first decreased, then increased, and finally decreased again with increasing temperature (the so-called inverted S shape); the intensity showed a temperature dependence similar to that of amorphous semiconductors and disordered superlattices. These two phenomena suggest strong localization of carriers in Al0.48In0.52As, even when the effect of clustering is minimal. The PLE spectra showed excitonic enhancement only above 40 K. The first observation of phonons with PL is reported in Al0.48In0.52As. Energies of 29.6 and 45.9 meV were measured for the InAs-like and the AlAs-like LO phonons, respectively. These phonons could only be detected below 40 K, which, on the basis of selection rules for LO phonon scattering, confirms the localized nature of the luminescence.