Electrical and chemical analysis of Ti/Au contacts to β-Ga2O3.

Chemical and electrical measurements of Ti/(010) β-Ga₂O₃ and Ti/(001) β-Ga₂O₃ interfaces were conducted as a function of annealing temperature using x-ray photoelectron spectroscopy (XPS), current density–voltage (J–V), and capacitance–voltage (C–V) measurements. XPS revealed partial Ti oxidation at both interfaces in the as-deposited condition, with more Ti oxidation on the (001) β-Ga₂O₃ epilayer surface than the (010) β-Ga₂O₃ substrate surface. The amount of oxidized Ti increased with annealing temperature. The Schottky barrier heights for as-deposited (unannealed) Au/Ti/(010) β-Ga₂O₃ and Au/Ti/(001) β-Ga₂O₃ contacts as determined from J–V and C–V measurements were between 0.64 and 0.83 eV. Shifts in XPS core level peaks for Ti/(010) β-Ga₂O₃ suggest that the Schottky barrier height decreases with temperature up to 350 °C for 10-min anneals and increases for 10-min anneals ≥460 °C. Taken together, the results suggest a strong dependence of Ti reactivity on the β-Ga₂O₃ surface, which can affect the electrical performance and stability of Ti/β-Ga₂O₃ ohmic contacts at elevated temperatures. [ABSTRACT FROM AUTHOR]