Shubnikov-de Haas Oscillations inn-Type GaAs

Abstract

Shubnikov-de Haas oscillations in $n$-type GaAs are reported for four samples with carrier concentrations between 2\ifmmode\times\else\texttimes\fi{}${10}^{16}$ and 2\ifmmode\times\else\texttimes\fi{}${10}^{17}$/${\mathrm{cm}}^{3}$. Temperatures employed ranged from 1.3 to 4.2\ifmmode^\circ\else\textdegree\fi{}K, while magnetic fields were 34 kG and below. Scattering times were such that $0.1<{\ensuremath{\omega}}_{c}\ensuremath{\tau}<0.9$ for all measurements. Carrier concentrations derived from the oscillations agreed with Hall determinations to better than 10%. Only the fundamental oscillation in ${B}^{\ensuremath{-}1}$ was observed, the phase angle being $\frac{1}{4}\ensuremath{\pi}$ within a considerable uncertainty forced by the extrapolation to ${B}^{\ensuremath{-}1}=0$. Amplitude variation with temperature and field for the two samples with carrier concentration greater than ${10}^{17}$/${\mathrm{cm}}^{3}$ was adequate to permit calculation of effective mass (0.058\ifmmode\pm\else\textpm\fi{}0.006) and Dingle temperature (\ensuremath{\sim}12\ifmmode^\circ\else\textdegree\fi{}K). The magnitude of the amplitude agreed with theory to within a factor of 7.