Self-consistent analysis of Si δ-doped layer placed in a non-central position in GaAs structure

We have theoretically studied the influence of a position of a δ-doped layer relative to the semiconductor surface on its electronic structure and a free charge carrier profile. The semiconductor material was GaAs and δ-doping was assumed to be formed by Si atoms with uniform distribution in the δ-layer. The electronic structure was calculated by solving Poisson and Schrödinger equations self-consistently. As a result of calculations the confining potential, subband energy levels, their occupation probabilities and the total free carrier density were obtained. In the study it was assumed that the Fermi level is not pinned at the semiconductor surface, there is no charge transfer from the semiconductor to the surface and charge neutrality is valid in the semiconductor as a whole. It was found that shifting the δ-doped layer from the centre toward the semiconductor surface causes a creation of another potential well with electron concentration peak at the other surface of the sample. Similar effect of the side peak creation was described in the literature by applying external electric field to the structure. Further approaching of the semiconductor surface leads to alternating population of the energy levels between the two potential wells.