Temperature-Dependent Electrical Properties of Graphitic Carbon Schottky Contacts to β-Ga2O3

Graphitic (sp(2)-rich) carbon Schottky contacts to ((2) over bar 01) beta-Ga2O3 were fabricated using sputtering and energetic ion deposition with and without the use of an oxygen plasma. As-deposited contacts exhibited room temperature effective barrier heights between 0.80 and 1.20 eV, depending on the deposition technique. After moderate heat treatment (595 K in N-2) the work function of the oxygenated graphitic contacts increased by 0.5-0.8 eV. This resulted in a permanent increase in barrier height (up to 1.6 eV) and a corresponding 3-4 orders of magnitude increase in current rectification (at +/- 3 V). The barrier heights of the heat-treated oxygenated graphitic Schottky contacts agree well with the Mott-Schottky model, suggesting an absence of Fermi level pinning at the C/beta-Ga2O3 interface.