Energy relaxation mechanisms in n-type GaAs from magnetophonon spectroscopy

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Abstract
Magnetophonon resonances have been observed in the warm-electron coefficient beta in n-GaAs, at temperatures between 55K and 77K. The resonances seen indicates a rapid change in importance of the energy relaxation processes involving LO phonons from impurity site capture at 60K to inter-Landau level transitions at 70K. The relative amplitudes of the different magnetophonon series was measured precisely by the use of Fourier analysis. The observed behaviour is interpreted in terms of a strong distortion of the electron distribution at energies one LO phonon distant from the donor ground state. At 77K it is found that high electric fields can change the sign of the extrema and also produce a small shift in the position of the extrema.