Leakage Current Reduction in β-Ga2O3 Schottky Barrier Diodes by CF4 Plasma Treatment

This letter reports on the suppression of reverse leakage current (I-r) in beta-Ga2O3 Schottky barrier diodes (SBDs) through Schottky barrier modification by a low power CF4-plasma treatment prior to Schottky metal deposition. Revealed by an x-ray photoelectron spectroscopy (XPS) analysis, the fluorine-plasma treatment brought an incorporation of fluorine ions and depletion of silicon donors in the near surface region of the beta-Ga2O3, and thus raised its surface potential by around 0.14 eV. Furthermore, insulatingGaFx was likely created at the Schottky interface. Attributed to the fluorine-plasma-modified Schottky barrier, a reduced I-r by around four orders of magnitude and enhanced blocking voltage (V-block) from 150 V to 470 V at I-r = 100 mu A/cm(2) have been achieved without degrading the forward characteristics. Different from the untreated device whose I-r was purely governed by the thermionic field emission (TFE), the fluorine-plasma-treated SBD showed a greatly suppressed TFE-current until a space-chargelimited current (SCLC) started to dominate at around -500 V.