Hole sub-bands on silicon surfaces

The sub-band structure of hole space-charge layers in Si is investigated both theoretically and experimentally. The sub-band energies and the k/sub /// dispersion are calculated self-consistently in the Hartree approximation. The results are compared with measured sub-band excitations as obtained by resonant inelastic light scattering techniques. Various transitions are observed in a wide range of carrier concentrations on (100) as well as (110) and (111) Si surfaces. From the lineshapes and linewidths information on the k/sub /// dispersion of the individual sub-bands is obtained. By analysing the polarisation of the scattered light the authors were able to separate collective and single-particle excitations.