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

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Abstract
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.