Interface chemistry and electrical properties of tungsten Schottky-barrier contacts to GaAs

A correlation between the interface chemistry and the electrical properties of evaporated tungsten Schottky-barrier contacts to GaAs is made by using data obtained by x-ray photoemission spectroscopy (XPS), current-voltage (I-V), and capacitance-voltage (C-V) techniques. A chemical reaction and associated nonabruptness was observed both at ideal (initial clean surface) and at practical (initial native-oxide covered surface) W-GaAs interfaces during Schottky-barrier formation at room temperature. The XPS measured W Schottky-barrier height for both types of interface is 0.9 eV. I-V and C-V measurements were made for a sequence of anneal temperatures up to 650 °C; changes in the contact electrical properties occurred at each temperature. The reactive W contacts are compared to relatively nonreactive Au contacts to GaAs similarly prepared and characterized. The I-V and C-V properties of Schottky-barrier contacts are found to be strongly influenced by the chemistry associated with interface formation.