Accurate evaluation of subband structure in a carrier accumulation layer at an n-type InAs surface: LDF calculation combined with high-resolution photoelectron spectroscopy

Abstract

Adsorption on an n-type InAs surface often induces a gradual formation of a carrier-accumulation layer at the surface. By means of high-resolution photoelectron spectroscopy (PES), Betti et al. made a systematic observation of subbands in the accumulation layer in the formation process. Incorporating a highly nonparabolic (NP) dispersion of the conduction band into the local-density-functional (LDF) formalism, we examine the subband structure in the accumulation-layer formation process. Combining the LDF calculation with the PES experiment, we make an accurate evaluation of the accumulated-carrier density, the subband-edge energies, and the subband energy dispersion at each formation stage. Our theoretical calculation can reproduce the three observed subbands quantitatively. The subband dispersion, which deviates downward from that of the projected bulk conduction band with an increase in wave number, becomes significantly weaker in the formation process. Accurate evaluation of the NP subband dispersion at each formation stage is indispensable in making a quantitative analysis of collective electronic excitations and transport properties in the subbands.