Method of choice for the fabrication of highquality β-gallium oxide-based Schottky diodes

Electrical properties of differently fabricated Pt(O-x) Schottky contacts on heteroepitaxial grown beta-gallium oxide thin films have been investigated at room temperature using currentvoltage measurements. A partial oxidation of contact metal leads to a significant increase of the homogeneous barrier by 0.3-0.4 eV compared to their metallic counterparts. The properties of the Schottky contacts are highly dependent on the kinetic energy of the incident metal (oxide) particles during contact deposition. Large kinetic energies cause a significant decrease of the effective barrier height, which is probably connected to the additional generation of defects close to the metal/ semiconductor interface. Using PtOx as contact material, the additional oxygen at the interface heals defects generated during the formation of the Schottky barrier. Long-throw sputtering combines a low kinetic energy of the metal particles and the possibility of fabricating partially oxidized PtOx as contact material. Therefore, this technique is most suitable for the fabrication of highly rectifying gallium oxide based Schottky contacts. On heteroepitaxial thin film samples on c-plane sapphire the rectification is larger than 10(6) at +/- 2 V, the ideality factor is below 1.5 and the effective barrier height above 1.3 eV.