Coherent exciton–biexciton dynamics in GaN

Abstract

Spectrally resolved and time-integrated four-wave mixing are used to measure the polarization dependence of biexcitonic signals and quantum beats between two-$A$-exciton ${(X}_{A}{X}_{A}^{*})$ and A-biexciton ${(X}_{A}{X}_{A})$ states in a high-quality GaN epilayer. Mixed beats with two periods are observed: the first beating period corresponds to the energy splitting between ${X}_{A}{X}_{A}^{*}$ and ${X}_{A}{X}_{A};$ the second period corresponds to beating between A excitons ${(X}_{A})$ and donor bound excitons ${(D}^{0}X).$ We also measure the polarization-dependent B-biexciton ${(X}_{B}{X}_{B})$ signal. The effective masses for the A and B holes are deduced from the binding energy.