Comparison of Schottky contacts on β-gallium oxide thin films and bulk crystals

The electrical properties of identically fabricated PtOx Schottky contacts on ((2) over bar 01)-oriented gallium oxide thin films and bulk crystals were investigated using current-voltage measurements at room temperature. The homogeneous barrier height of the Schottky contacts on thin films is 1.55 +/- 0.15 eV, which is significantly smaller than that of those fabricated on bulk single crystals, 2.01 +/- 0.12 eV. This large difference indicates an upward band bending of 0.4-0.5 eV at the surface of the bulk crystals in the as-received state, which is explained by the larger net doping density of the thin films compared to the single crystals. (C) 2015 The Japan Society of Applied Physics