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

While the optically detected cyclotron resonance (ODCR) technique is a wide ly applied technique for the study of semiconductors, the effect of cyclotr on 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 spec trum 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-e lectron temperature.