Reversible interaction of hydrogen with thin layers of thermally grown silicon dioxide

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Abstract
Some effects of hydrogen on the electrical properties of Pd-metal-thin (≊10 nm) oxide-silicon capacitors are reported. High-frequency (1 MHz) and quasistatic capacitance voltage curves are measured at 100 °C as a function of hydrogen partial pressure in a background atmosphere of 20% O2/Ar. Besides the standard hydrogen-induced shift of the capacitance-voltage characteristics we find: (1) an increase in the accumulation capacitance with increasing hydrogen partial pressure, and (2) a nonmonotonic increase in the quasistatic capacitance minimum with increasing hydrogen pressure. The relative increase in the accumulation capacitance is shown to be related to the square of the hydrogen-induced voltage shift (and hence to the square of the concentration of hydrogen atoms at the Pd-SiO2 interface). We discuss our findings, based on existing hydrogen-silicon dioxide models, to interpret the effects of hydrogen on the high-frequency and quasistatic capacitance characteristics.