Fourier analysis of magnetophonon and two-dimensional Shubnikov-de Haas magnetoresistance structure

The advantages of Fourier analysis of quantum magnetoresistance peaks are demonstrated in the first application of these techniques to a study of the magnetophonon effect in a number of semiconductors and also to the subnikov-de Haas effect in MOS devices. The change in amplitude of these series is investigated as a function of applied electric field. The phonons involved are identified and are all shown to be intervalley with the exception of the highest energy phonon. In contrast Fourier analysis of the magnetophonon spectrum for n-Ge shows that intervalley scattering in this material is weaker by at least a factor of 20 than intravalley scattering by high energy phonons. With both n-Ge and n-GaAs considerable sharpening of the magnetophonon peaks is detected and a strong second harmonic of the fundamental magnetophonon frequency is observed in each case on the Fourier analysis. With n-GaAs as the temperature dependence of the amplitude and damping of the magnetophonon series is compared with the theory developed by Barker (1972).