Charge Transport in MOS-Structures with Low-Temperature Silicon Dioxide Films

Charge transport and accumulation is investigated in SiO2 layers produced at 250 °C oxidation of monosilane and in SiO2 layers obtained in a high-vacuum system from SiO molecule flow in O2. It is found that the deposition of Al onto OH-containing SiO2 films an intermediate Al oxide layer influencing the charge transport is formed. SiO2 layers produced by two different techniques have the same characteristics of charge transport and accumulation. The charge transport is shown to be well described within the hopping mechanism of conduction among localized states near the middle of the forbidden zone of dielectric with a density of states of 1020 to 1021 cm−3 and a zone width of the localized states of ≈0.8 eV. The existence of localized states is proved by experiments on the accumulation of charge of both signs in the dielectric bulk. [Russian text Ignored.]