Four‐wave‐mixing study of exciton fine structure in GaN

Abstract

Dephasing dynamics of exciton fine structure (EFS) caused by long and short range exchange interactions in GaN was investigated by using a four‐wave‐mixing (FWM) spectroscopy. The type of exchange interactions was selected by samples (uniaxially strained c ‐plane GaN films and a thick bulk GaN) and their geometries in optical excitation. Since each component of EFS is highly polarized, the polarization‐dependent FWM spectra successfully resolve the dephasing dynamics in the individual EFS resonances. The results show a difference in dephasing time, suggesting a contribution of anisotropic exchange interaction (AEI). (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)