Magnetophonon Resonance and Fourier Analysis in n-GaAs

Abstract

With the use of magnetic field modulation technique up to eighteen magnetophonon peaks are observed in the transverse and longitudinal magnetoresistance of high purity epitaxial n-GaAs. Fourier analysis reveals the second harmonic component resulting in a sharpening of the oscillatory structure in the transverse magnetoresistance and extrema associated with the two LO phonon process in the longitudinal magnetoresistance in addition to the ordinary magnetophonon series. Two methods are described to obtain the damping factor \barγ which is found to be 0.63 from the Fourier analysis and 0.60 from the method described in this paper for the specimen with the highest mobility (1.7×10⁵ cm²/V·s) at 77 K. The temperature dependence of \barγ for the high purity n-GaAs exhibits a variation T^0.25 at low temperatures, which indicates an importance of the band tailing effect for the damping process. The effective mass is determined to be m^*=0.0682m₀ at 77 K.