Oscillatory Magnetoconductance ofp-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 $0.6m_0$ to $1m_0$ in the carrier concentration range (1 to 3.5) × ${10}^{12}$ ${\mathrm{cm}}^{-2\mathrm{}}$. 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 × ${10}^{11}$ ${\mathrm{cm}}^{-2\mathrm{}}$) are reported.