Electromodulation spectroscopy of highly mismatched alloys

Abstract

The electronic band structure of highly mismatched alloys (HMAs) was very successfully explored using electromodulation (EM) spectroscopy, i.e., photoreflectance (PR), electroreflectance, and contactless electroreflectance (CER). With these techniques, the optical transitions between the valence band and the E- and E+ bands, which are formed in the conduction band of dilute nitrides and dilute oxides, were observed and used to formulate the band anticrossing model, which well describes the electronic band structure of HMAs. In this tutorial, principles of EM spectroscopy are presented and shortly discussed. Special attention is focused on PR and CER techniques, which are nondestructive and have recently been widely applied to study the electronic band structure of HMAs and low dimensional heterostructures containing HMAs. For these methods, experimental setups are described, and theoretical approaches to analyze the experimental data are introduced. Finally, to show the utility of EM spectroscopy, selected examples of the application of this method to study various issues in HMAs are presented and briefly discussed.