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Semiconductor Physics, Quantum Electronics & Optoelectronics. 2005. V. 8, N 4. P. 038-054.
Electron states at the Si-SiO2 boundary
(Review)
V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine,
41, prospect Nauky, 03028 Kyiv, Ukraine
Abstract. This review is aimed at analysis of the system of discrete and continuously
distributed boundary electron states (BES) on (111) and (100) silicon surfaces in the SiSiO2 structures prepared mainly using thermal oxidation of silicon. Used here are
literature data as well as results obtained by authors when studying the temperature and
electric field dependencies of the capacitive photovoltage. It has been ascertained that the
BES system consists of a continuous U-like distribution in the silicon forbidden gap and
from the discrete BES as well. There developed are two discrete BES in the thermally
oxidized Si(111)-SiO2 structure, while in the Si(100)-SiO2 structure – four ones. These
results well coordinated with ESR investigations were obtained using the method of
temperature dependencies for capacitive photovoltage without application of an external
electric field. As shown, application of various electric-field methods enables to
determine only effective parameters of discrete and especially continuously distributed
BES, which depend on the temperature of measurements, silicon resistivity and
conditions of preparation of the Si-SiO2 boundary. Considered are the features of preoxidation treatment of the silicon surface and its oxidation, the character of the
intermediate layer between Si and SiO2, and the influence of such external factors as
annealing in various ambient atmospheres, irradiation and high electric fields as well.
Keywords: electron states, conductivity.
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