Subcritical barrier AlN/GaN E/D-mode HFETs and inverters
نویسندگان
چکیده
Enhancementand depletion-mode AlN/GaN HFETs have been fabricated with a subcritical barrier design: a twodimensional electron gas (2DEG) is induced in the highly resistive as-grown heterostructure when a suitable capping material is deposited over the ultrathin AlN barrier. In this bottom-up approach 2DEGs can be locally induced by patterned cap layers on subcritical barrier AlN/GaN heterostructures, which can enable the monolithic integration of enhancementand depletion-mode HFETs. An inverter circuit with 1.5 nm ultrathin AlN barrier Eand D-mode HFETs was successfully demonstrated with reasonable voltage transfer characteristics, noise margin, and gain. To our best knowledge this is the first reported inverter based on subcritical barrier III– V nitride heterostructures. Integration of Eand D-mode HFETs in a subcritical barrier AlN/GaN heterostructure, where n2DEG" 0 in the as-grown structure. A patterned cap locally enhances 2DEG at the AlN/ GaN hetero-interface due to barrier lowering. It is an additive approach in contrast to the conventional gate recessing technique.
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