Electronic properties of gated -doped semiconductors

The quantum and transport subband mobilities as a function of applied bias were calculated for a gated -doped semiconductor. The electronic spectra (envelope wavefunctions, subband energies and Fermi energy) for the structure under bias used as input in the calculations were obtained by either solving self-consistently Schrödinger and Poisson equations or by solving the Schrödinger equation with a confining potential determined by the Thomas - Fermi semiclassical approximation. In the first case the screening of the electron-ionized impurity interaction was treated in the random phase approximation, whereas in the latter case the two-dimensional Thomas - Fermi model of screening was used. Results show that although the semiclassical approach offers the advantage of greater simplicity, it describes reliably the carrier mobility in the fundamental subband only. The dependence of the mobility of carriers in individual subbands on applied bias correlates with the evolution with bias of the overlap between subband wavefunctions and the doped-layer region.