Temperature-dependent cyclotron resonances in n-type GaAs

We report temperature-dependent cyclotron resonances of electrons in bulk GaAs in a temperature regime from about 10-300 K. Due to the nonparabolicity of the GaAs conduction band at sufficiently high temperatures and magnetic-field strengths, several individual Landau transitions are observed. A single line of strongly overlapping Landau transitions is found at higher temperatures and also in the case of small magnetic- field strength. Band coupling, electron-phonon interaction, and the electron spin influence the cyclotron resonance. However, from liquid-helium temperatures up to room temperature, the transition energies are essentially independent of temperature. Scattering times, which govern the broadening of the Landau transitions, decrease in magnitude with increasing magnetic-field strength as well as with temperature, and there is no simple relation to magnetotransport scattering times.