Leakage Current Reduction in β-Ga<sub>2</sub>O<sub>3</sub> Schottky Barrier Diodes by CF<sub>4</sub> Plasma Treatment
Haoxun Luo, Huaxing Jiang, Zimin Chen, Yanli Pei, Qian Feng, Hong Zhou, Xing Lü, Kei May Lau, Gang Wang
Abstract
This letter reports on the suppression of reverse leakage current (Ir) in β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Schottky barrier diodes (SBDs) through Schottky barrier modification by a low power CF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> -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 β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , and thus raised its surface potential by around 0.14 eV. Furthermore, insulating GaFx was likely created at the Schottky interface. Attributed to the fluorine-plasma modified Schottky barrier, a reduced Ir by around four orders of magnitude and enhanced blocking voltage (Vblock) from 150 V to 470 V at Ir = 100μ A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> have been achieved without degrading the forward characteristics. Different from the untreated device whose Ir 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.