Contactless Electroreflectance Spectroscopy of ZnO with Different Polarization-Direction Probe Beams

Abstract

Contactless electroreflectance (CER) spectra of ZnO bulk has been measured at 300K. It is observed the difference between the CER spectra using by the polarization E of probe light perpendicular ( Ec) and parallel ( Ec) to the c-axis of the m-plane ZnO. In addition, a mercury lamp was focused on the sample to reduce its strength of electric field. It was observed that the CER spectrum was blue shifted with Hg lamp on. Hence, the observed features were attributed to excitonic transitions. The experimental spectra were fitted by Lorentzian lineshapes. The energies of the A ( B), B(A), and C transitions can be determined.