Epitaxial High-K Dielectric Grown by Atomic Layer Deposition on Wide Bandgap Semiconductors

Abstract

Wide band gap semiconductors, including GaN, SiC and Ga2O3, are considered as the substrate for next generation power conversion devices. In order to improve the power conversion efficiency, an epitaxial MgxCa1-xO gate dielectric deposited by atomic layer deposition (ALD) is developed in this work. The epitaxial relationship between the MgxCa1-xO film and three substrates are studied with TEM and XRD. The low defects interface of MgxCa1-xO/GaN is confirmed with high temperature capacitance-voltage study. The relationship between band offset and interfacial defects has been established with La2O3/GaAs as an example. Two record breaking high electron mobility transistors (HEMT) with epitaxial MgxCa1-xO as an oxide have been developed. Additionally, a high on/off (1011) enhancement mode HEMT device is developed with a combination of epitaxial MgxCa1-xO dielectric and Fin-FET structure.