Browsing by Author "Datta, Suman"
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Item Atomically Thin Resonant Tunnel Diodes Built from Synthetic van der Waals Heterostructures(Nature Pub. Group) Lin, Yu-Chuan; Ghosh, Ram Krishna; Addou, Rafik; Lu, Ning; Eichfeld, Sarah M.; Zhu, Hui; Li, Ming-Yang; Peng, Xin; Kim, Moon J.; Li, Lain-Jong; Wallace, Robert M.; Datta, Suman; Robinson, Joshua A.; A-5283-2008 (Wallace, RM); A-2297-2010 (Kim, MJ)Vertical integration of two-dimensional van der Waals materials is predicted to lead to novel electronic and optical properties not found in the constituent layers. Here, we present the direct synthesis of two unique, atomically thin, multi-junction heterostructures by combining graphene with the monolayer transition-metal dichalcogenides: molybdenum disulfide (MoS₂), molybdenum diselenide (MoSe₂) and tungsten diselenide (WSe₂). The realization of MoS₂-WSe₂-graphene and WSe₂-MoS₂-graphene heterostructures leads to resonant tunnelling in an atomically thin stack with spectrally narrow, room temperature negative differential resistance characteristics.;Item High Quality HfO₂/p-GaSb(001) Metal-Oxide-Semiconductor Capacitors with 0.8 Nm Equivalent Oxide ThicknessBarth, Michael; Rayner, G. Bruce,Jr.; McDonnell, Stephen; Wallace, Robert M.; Bennett, Brian R.; Engel-Herbert, Roman; Datta, SumanWe investigate in-situ cleaning of GaSb surfaces and its effect on the electrical performance of p-type GaSb metal-oxide-semiconductor capacitor (MOSCAP) using a remote hydrogen plasma. Ultrathin HfO₂ films grown by atomic layer deposition were used as a high permittivity gate dielectric. Compared to conventional ex-situ chemical cleaning methods, the in-situ GaSb surface treatment resulted in a drastic improvement in the impedance characteristics of the MOSCAPs, directly evidencing a much lower interface trap density and enhanced Fermi level movement efficiency. We demonstrate that by using a combination of ex-situ and in-situ surface cleaning steps, aggressively scaled HfO₂/p-GaSb MOSCAP structures with a low equivalent oxide thickness of 0.8 nm and efficient gate modulation of the surface potential are achieved, allowing to push the Fermi level far away from the valence band edge high up into the band gap of GaSb. (c) 2014 AIP Publishing LLC.