Threshold energies of high-field-induced hole currents and positive charges in SiO2 layers of metal-oxide-semiconductor structures

Abstract

The threshold energies of high-field-induced oxide hole currents and positive oxide charges were examined by using metal-oxide-semiconductor field-effect transistors (MOSFETs) with oxide layers of 6 nm. Effects of three anode materials, polysilicon, aluminum, and gold, were studied. The same threshold energy was observed for generating both hole current and positive charges on MOSFETs with the same anode material. This result supports the proposal that both high-field-induced oxide hole current and positive oxide charges have the same origin. Different threshold energies were observed for different anode materials. The larger the anode electron barrier height, the smaller the observed threshold energy. Analyzing the experimental results indicates that holes which cause hole current and positive charges are generated at anode mainly due to electron direct excitation. The anode holes with energies larger than anode hole barrier height have dominant contribution to both high-field-induced oxide hole current and positive oxide charges. Contribution from the anode holes with energies smaller than anode hole barrier height can be ignored.