Lou, XiabingZhou, HongKim, Sang BokAlghamdi, SamiGong, XianFeng, JunWang, XinweiYe, Peide D.Gordon, Roy2017-01-172016Lou, Xiabing, Hong Zhou, Sang Bok Kim, Sami Alghamdi, Xian Gong, Jun Feng, Xinwei Wang, Peide D. Ye, and Roy G. Gordon. 2016. Epitaxial Growth of MgxCa1–xO on GaN by Atomic Layer Deposition. Nano Letters 16, no. 12: 7650–7654. doi:10.1021/acs.nanolett.6b03638.1530-6984http://nrs.harvard.edu/urn-3:HUL.InstRepos:29995335We demonstrate for the first time that a singlecrystalline epitaxial MgxCa1−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 MgxCa1−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 Mg0.25Ca0.75O has the lowest interfacial defect density. With this optimal oxide composition, a Mg0.25Ca0.75O/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.en-USepitaxydielectricGaNMOS-HEMTmagnesium calcium oxideJournal Article2016-12-2020162017-01-1710.1021/acs.nanolett.6b03638