Feasibility of optically detected cyclotron resonance to study electron mobility in ultrapure GaAs

Abstract

While the optically detected cyclotron resonance (ODCR) technique is a widely applied technique for the study of semiconductors, the effect of cyclotron resonance (CR) on the carrier capture and recombination processes is not well understood. We report on a comparative study of microwave CR and ODCR in photoexcited ultrapure GaAs at low temperatures. We found that the ODCR spectrum is broader and thus gives lower electron mobility than the CR spectrum under the same experimental conditions. To explain the discrepancy, a rate-equation model is developed for the dependence of the exciton density on the microwave power (free-electron temperature) under the CR conditions. A good agreement between the experimental data and the model calculations was obtained by assuming the exciton formation rate dependence on the hot-electron temperature.