Magnetoconductance study of accumulation layers onn−InAs

Far-infrared cyclotron resonance and Shubnikov — de Haas oscillations are used to explore accumulation-layer properties of degenerate $n-\mathrm{I}\mathrm{n}\mathrm{A}\mathrm{s}$. The bulk concentrations studied range from 2 × ${10}^{15}$ to 1 × ${10}^{17}$ ${\mathrm{cm}}^{-3\mathrm{}}$. At the lowest concentration, subband masses, occupations, and relaxation rates are found which are in general agreement with earlier work. For the higher concentrations, the Shubnikov — de Haas oscillations exhibit effects characteristic of a degenerate semiconductor as predicted by Baraff and Appelbaum: Abrupt changes in bound carrier density occur when an additional subband is populated and are compensated by a corresponding decrease of mobile charge at the surface. The self-consistent accumulation potential supports more bound states than observed in earlier tunneling work. A determination of the binding energies of these states results from our measurement of subband masses and occupations.