Epitaxial Growth of MgxCa1-xO on GaN by Atomic Layer Deposition

Xiabing Lou; Hong Zhou; Sang Bok Kim; Sami Alghamdi; Xian Gong; Jun Feng; Xinwei Wang; Peide D Ye; Roy G Gordon

doi:10.1021/acs.nanolett.6b03638

Epitaxial Growth of Mg_xCa_1-xO on GaN by Atomic Layer Deposition

Nano Lett. 2016 Dec 14;16(12):7650-7654. doi: 10.1021/acs.nanolett.6b03638. Epub 2016 Dec 2.

Authors

Xiabing Lou¹, Hong Zhou², Sang Bok Kim¹, Sami Alghamdi², Xian Gong¹, Jun Feng¹, Xinwei Wang¹, Peide D Ye², Roy G Gordon¹

Affiliations

¹ Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States.
² School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47906, United States.

PMID: 27960444
DOI: 10.1021/acs.nanolett.6b03638

Abstract

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.

Keywords: Epitaxy; GaN; MOS-HEMT; dielectric; magnesium calcium oxide.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.