Effective mass and band nonparabolicity in remote doped Si/Si0.8Ge0.2 quantum wells

Abstract

The effective masses in remote doped Si/Si0.8Ge0.2/Si quantum wells having sheet densities, Ns in the range 2×1011-1.1×1012cm-2 have been determined from the temperature dependencies of the Shubnikov-de Haas oscillations. The values obtained increase with magnetic field and Ns. This behavior is taken as evidence for the nonparabolicity of the valence band and accounts for the discrepancies in previously reported masses. Self-consistent band structure calculations for a triangular confinement of the carriers have also been carried out and provide confirmation of the increase in mass with Ns. Theory and experiment give extrapolated Γ point effective masses of 0.21 and 0.20 of the free-electron mass, respectively.© 1995 American Institute of Physics.