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Title:Metal-assisted chemical etching of β-gallium oxide
Author(s):Huang, Hsien-Chih
Advisor(s):Li, Xiuling
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Metal-Assisted Chemical Etching, β-Ga2O3
Abstract:β-Ga2O3, with an ultra-wide bandgap (UWB) of ~ 4.6 – 4.9 eV and bulk substrate availability, has drawn enormous interest in the power electronics community. Fabricating high-aspect-ratio β-Ga2O3 3D nanostructures without surface damage is essential for next-generation power electronics. Nonetheless, dry etch typically damages the surface due to high-energy ions, while most wet etching techniques can only produce very limited aspect ratios. In this thesis, β-Ga2O3 fin arrays by inverse metal-assisted chemical etching (MacEtch), under UV light irradiation, with a high aspect ratio and excellent surface quality, are demonstrated. The strongly crystal-orientation-dependent etching behaviors are found and three kinds of vertical structures are formed after the MacEtch process. The Schottky barrier heights (SBHs) between platinum (Pt) and different MacEtch-formed β-Ga2O3 surfaces and sidewalls are found to decrease as the aspect ratio of the β-Ga2O3 structure increases. This behavior is attributed to the varying oxygen composition on the surface after MacEtch, as shown by the XPS and TEM examination. Very little hysteresis has been observed in the capacitance-voltage characteristics of the 3D Pt/ Al2O3/ β-Ga2O3 MOS capacitor structures, and the lowest interface trap density extracted from etched interfaces is only 2.73×1011cm-2-eV-1, which is comparable to that of other published values of unetched β-Ga2O3 surfaces. This confirms that MacEtch is an effective etching method for producing high quality β-Ga2O3 3D structures.
Issue Date:2019-12-10
Rights Information:Copyright 2019 Hsien-Chih Huang
Date Available in IDEALS:2020-03-02
Date Deposited:2019-12

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