Field-Dependent Charge Carrier Dynamics in GaN: Excitonic Effects

The variation of the electrode potential of an n-GaN/solution heterojunction that allows for the convenient discrimination between free electron-hole pair generation and exciton creation at room temperature was shown. The anomalous potential dependence of the intensity of the excitonic luminescence was recognized to incomplete ionization of excitons in the space charge region. The relative amount of sub and near gap photocurrent increases with the depletion layer width consistent with exciton ionization in the depletion layer. The results show that when the temperature is raised the exciton lines broaden and at room temperature are hidden by the fundamental band-band absorption.