Space-charge layers on Ge surfaces. I. dc conductivity and Shubnikov—de Haas effect

We have prepared metal-insulator-semiconductor (M-I-S) structure for major symmetry planes of Ge. The samples are examined and characterized systematically by capacitance-voltage (C-V) and conductivity measurements [σ(V) and dσdVg]. Lacquer-coated specimens of (111) surfaces prepared in this work give a new period in the magneto-oscillation spectrum and thus resolve the question of "missing" electrons raised in the experiments of Weber et al. We determine the energy splitting of the two lowest electron subbands on (111) Ge and predict the occupancy of the lowest level of the threefold degenerate valleys for Nₛ above {~}1.0 ×{} 10¹² cm^-2.