EFFECT OF SPATIAL LOCALIZATION OF DOPANT ATOMS ON THE CONFINING POTENTIAL AND ELECTRON SUBBAND STRUCTURE IN DELTA-DOPED GAAS-SI

In conjunction with Raman scattering measurements, we have performed calculations of the electronic structure of nominally delta-doped GaAs:Si in which the dopant layer has been positioned close (< 300 angstrom) to the surface, with a 200 angstrom spread towards the surface. The band-bending due to the Fermi level pinning at the surface gives rise to a strong asymmetric shape for the space charge induced potential well. Electron subband energies and wave functions are determined self-consistently and intersubband spin-density energies are compared with electronic Raman scattering results. A comparison of calculated and measured intersubband charge-density excitation energies is also made.