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This paper describes characteristics of normally-off mode GaN MISFETs fabricated on free-standing GaN substrates with high drain current Idss and specific low leakage current between adjacent devices. Nitrogen ion implantation isolation processes were adopted to fabricate isolation regions in self-aligned GaN MISFETs for the first time. Maximum drain current of 98 mA/mm, maximum trans conductance of 10 mS/mm and threshold voltage of +0.4 V were obtained for the devices. The leakage current between adjacent devices was low, i.e., in the range of 10-6 mA/mm, which is three orders of magnitude lower than those on sapphire substrates. These supreme results indicate a definite availability of normally-off self-aligned GaN MISFETs for power switching device applications. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Nitrogen ion implanted isolation technology to prevent leakage current between adjacent devices fabricated on p-GaN layers on sapphire substrate is described. Leakage current due to n-type inversion layers caused by Fermi level pinning at the p-GaN surface and buffer layers between sapphire substrate and GaN epitaxial layer is greatly reduced. With nitrogen ion implanted isolation technology of this study, leakage current between adjacent devices reduced five orders of magnitude compared to that without isolation layers. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

This paper describes normally-off GaN MOSFETs with high-k dielectric CeO2 films made by ion implantation. Ion implantation process reduces sheet and contact resistances of source and drain regions of this device. To obtain high Idss and gmmax, high-k dielectric CeO2 was used as gate oxide films for GaN MOSFETs for the first time. Nitrogen ion implantation isolation processes were also adopted to fabricate isolation region. Normally-off GaN MOSFETs with Idss of 350 mA/mm, gmmax of 40 mS/mm and threshold voltage of +0.5 V were obtained. The high Idss and normally-off mode show the potential and advantages of GaN MOSFETs for high voltage operations. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]