Importance of controlling oxygen incorporation into Hf O2 Sin-GaAs gate stacks

The interfacial change of Hf O2 Sin-GaAs gate stacks after high temperature annealing has been characterized using x-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and capacitance-voltage measurement. The properties of the interface are sensitive to the amount of incorporated oxygen. XPS measurement shows the formation of gallium and arsenic oxides with increasing annealing temperature. A PL emission from the Si interfacial passivation layer was observed after 900 °C annealing. With more oxygen incorporation, this PL emission was quenched. The measurement of the interface state density proved the generation of deep traps with too much oxygen incorporation. Depletion-mode metal-oxide-semiconductor field effect transistors using postdeposition annealing at 600 °C with and without post-metal-annealing at 900 °C have also been fabricated and characterized. Too much oxygen incorporation resulted into the degradation of mobility, subthreshold swing, and transconductance. The interfacial gallium and arsenic oxides might act as deep traps.