Effect of spatial localisation 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 (smaller than 300 Angström) to the surface, with a 200 Angström 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.