Oscillatory Magnetoconductance of p -Type Inversion Layers in Si Surfaces

We report the observation of Shubnikov-de Haas oscillations in the conductivity of surface holes in a p-type inversion layer of Si. The hole plasma is shown to be two dimensional. The effective mass varies from about 0.6m₀ to 1m₀ in the carrier concentration range (1 to 3.5) ×{} 10¹² cm^-2. It is proposed that the nonparabolic nature of Si valence band as well as many-body interaction affects the value of the effective mass. The hole gas is found to exist in one valley. Unexpected oscillations in the conductivity at low carrier concentration (less than 8 ×{} 10¹¹ cm^-2) are reported.