THRESHOLD ENERGIES OF HIGH-FIELD-INDUCED HOLE CURRENTS AND POSITIVE CHARGES IN SIO2 LAYERS OF METAL-OXIDE-SEMICONDUCTOR STRUCTURES

The threshold energies of high-field-induced oxide hole currents and p ositive 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 studi ed. The same threshold energy was observed for generating both hole cu rrent and positive charges on MOSFETs with the same anode material. Th is result supports the proposal that both high-field-induced oxide hol e current and positive oxide charges have the same origin. Different t hreshold energies were observed for different anode materials. The lar ger the anode electron barrier height, the smaller the observed thresh old energy. Analyzing the experimental results indicates that holes wh ich cause hole current and positive charges are generated at anode mai nly due to electron direct excitation. The anode holes with energies l arger than anode hole barrier height have dominant contribution to bot h high-field-induced oxide hole current and positive oxide charges. Co ntribution from the anode holes with energies smaller than anode hole barrier height can be ignored.