TEMPERATURE-DEPENDENT CYCLOTRON RESONANCES IN N-TYPE GAAS

We report temperatute-dependent cyclotron resonances of electrons in b ulk GaAs in a temperature regime from about 10-300 K. Due to the nonpa rabolicity of the GaAs conduction band at sufficiently high temperatur es and magnetic-field strengths, several individual Landau transitions are observed. A single line of strongly overlapping Landau transition s is found at higher temperatures and also in the case of small magnet ic-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 a re essentially independent of temperature. Scattering times, which gov ern the broadening of the Landau transitions, decrease in magnitude wi th increasing magnetic-field strength as well as with temperature, and there is no simple relation to magnetotransport scattering times.