Influence of Exciton-Exciton Interaction on Quantum Beats

Abstract

Spectrally resolved four-wave mixing measurements in wurtzite GaN show a dependence of the quantum beats' phase on incident polarizations. We observe different phases at the $A$-exciton and the $B$-exciton resonances when exciting with circular polarized light. The observed phase difference indicates that exciton-exciton interaction plays a major role in the quantum beat process. The developed analysis allows us to conclude that the spins of the electrons rather than the holes give the major contribution to the exciton-exciton interaction in GaN.