Epitaxial Rare Earth Oxide Growth on GaN for Enhancement-mode MOSFETs

J. S. Jur*, V. D. Wheeler*, M. T. Veety**, D. J. Lichtenwalner*, D. W. Barlage**, M. A. L. Johnson*
* Dept. of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, USA
** Dept. of Electrical and Computer Engineering, North Carolina State University, Raleigh, NC 27695, USA
Email: jsjur@ncsu.edu; Phone: (919) 515-6174
Keywords: High-κ, Rare Earth, Lanthanum Oxide, Scandium Oxide, GaN, MOSFET, Processing, MBE, Gallium Oxide, Passivation 

Abstract
Epitaxial growth of rare earth oxides are investigated as gate dielectric materials for GaN-based MOSFET devices. Real-time monitoring of La2O3 and Sc2O3 growth by MBE shows different growth progression of the epitaxial oxides. XPS analysis provides further detail about the growth of the oxides.
Electrical results show a >10x decrease in leakage current density for a 50 Ǻ La2O3 epitaxial dielectric as compared to a significantly thicker (600 Ǻ) Si3N4 dielectric on GaN, despite the high lattice mismatch between the La2O3 and GaN (21%). The performance enhancement is believed to be due in part to a native Ga2O3 passivation of the GaN during the initial stage of the epitaxial oxide growth.
 
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