Free-carrier generation by two-photon resonant excitation to the excitonic states in cuprous oxide

摘要

We have investigated nanosecond temporal responses of the cyclotron resonance signal of optically generated carriers in Cu_2 O. The rise time is found to increase significantly as the excitation photon energy approaches to the phonon-assisted absorption edge of the 1s exciton. We model the generation of free carriers by two-body collisions of excitons, which leads to the reasonable estimation of the Auger coefficient. We also demonstrate the excitation spectroscopy of cyclotron resonance by using a two-photon transition to the even-parity excitonic states. Their dynamics is discussed based on the quantum-number dependence of the resonance linewidth.