This paper studies the role of surface Si oxide as the quantum confinement barrier of the electronic states using ideal O-terminated Si(100) quantum slabs with different numbers of Si atomic layers. The optimized structures and their electronic states are calculated by the Vanderbilt ultrasoft pseudopotential method and compared with the electronic states of ideal H-terminated slabs calculated in the same way. The results show the surface states appear around the Fermi energy for O-terminated slabs, but the bulk states also appear below and above the surface states. Comparing the band gaps of the bulk states between O-terminated and H-terminated slabs, it is found that O-terminated structures confine the levels more strongly than H-terminated ones.
Kageshima, H. (1996). Effects of oxygen termination on the electronic states of silicon quantum slabs. Surface Science, 357–358, 312–316. https://doi.org/10.1016/0039-6028(96)00135-5