Electroreflectance and photoluminescence study on InGaN alloys

Abstract

Photoluminescence (PL) and electroreflectance (ER)measurements on In-rich In xGa 1-xN films grown by using metal-organic chemical vapor deposition at 640 °C and 670 °C were performed. Franz-Keldysh Oscillations (FKO's) were observed in the ER spectra. The analysis of the FKO's shows phase separation of InN for the In 0.8Ga 0.2N film, regardless of the growth temperature, whereas in the PL spectrum multiple peaks were resolved only in the sample grown at 640 °C. This indicates that phase separation exists in this kind of In-rich InGaN alloy independent of the growth temperature. From a deconvolution of the FKO signal in the ER spectra, the bandgap energy of In-rich In xGa 1-xN could be estimated. The dependence of the bandgap energy of the In xGa 1-xN alloy on the In composition (x) was obtained from this information.