ANALYSIS OF PHOTOEMISSION AND INVERSE PHOTOEMISSION SPECTRA OF SI(111) AND SULPHUR-PASSIVATED INP(001) SURFACES

摘要

Photoemission (PES) and inverse-photoemission spectra (IPES) for the sulphur-passivated InP(001) surface are compared with theoretical predictions based an density-functional calculations. As a test case for our methods, we also present a corresponding study of the better known Si(111) surface. The reported spectra for InP(001)-S agree well with the calculated ones if the surface is assumed to consist of a mixture of two phases, namely, the fully S-covered (2X2)-reconstructed structure, which contains four S atoms in the surface unit cell, and a (2X2) structure containing two S and two P atoms per unit cell. The latter has recently been identified in total-energy calculations as well as in core-level spectra of S-passivated InP(001) surfaces under annealing. The experimental IPES for Si(111)-(2X1) is in excellent agreement with the calculations. The comparison of the experimental PES with our calculations provides additional considerations regarding the nature of the sample surface. It is also found that the commonly used density-of-states approximation to the photoemission and inverse-photoemission spectra is not valid for these systems. [S0163-1829(97)09040-1]. [References: 26]