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• 作者：Xiabing Lou ; Hong Zhou ; Sang Bok Kim ; Sami Alghamdi ; Xian Gong ; Jun Feng ; Xinwei Wang ; Peide D. Ye ; Roy G. Gordon
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：December 14, 2016
• 年：2016
• 卷：16
• 期：12
• 页码：7650-7654
• 全文大小：421K
• ISSN：1530-6992

文摘

We demonstrate for the first time that a single-crystalline epitaxial Mg_xCa_1–xO film can be deposited on gallium nitride (GaN) by atomic layer deposition (ALD). By adjusting the ratio between the amounts of Mg and Ca in the film, a lattice matched Mg_xCa_1–xO/GaN(0001) interface can be achieved with low interfacial defect density. High-resolution X-ray diffraction (XRD) shows that the lattice parameter of this ternary oxide nearly obeys Vegard’s law. An atomically sharp interface from cross-sectional transmission electron microscopy (TEM) confirmed the high quality of the epitaxy. High-temperature capacitance–voltage characterization showed that the film with composition Mg_0.25Ca_0.75O has the lowest interfacial defect density. With this optimal oxide composition, a Mg_0.25Ca_0.75O/AlGaN/GaN metal–oxide–semiconductor high-electron-mobility (MOS-HEMT) device was fabricated. An ultrahigh on/off ratio of 10¹² and a near ideal SS of 62 mV/dec were achieved with this device.