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Influence of O-2 flow rate on HfO2 gate dielectrics for back-gated graphene transistors

Ganapathi, Kolla Lakshmi and Bhat, Navakanta and Mohan, Sangeneni (2014) Influence of O-2 flow rate on HfO2 gate dielectrics for back-gated graphene transistors. In: SEMICONDUCTOR SCIENCE AND TECHNOLOGY, 29 (5).

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Official URL: http://dx.doi.org/10.1088/0268-1242/29/5/055007


HfO2 thin films deposited on Si substrate using electron beam evaporation, are evaluated for back-gated graphene transistors. The amount of O-2 flow rate, during vaporation is optimized for 35 nm thick HfO2 films, to achieve the best optical, chemical and electrical properties. It has been observed that with increasing oxygen flow rate, thickness of the films increased and refractive index decreased due to increase in porosity resulting from the scattering of the evaporant. The films deposited at low O-2 flow rates (1 and 3 SCCM) show better optical and compositional properties. The effects of post-deposition annealing and post-metallization annealing in forming gas ambience (FGA) on the optical and electrical properties of the films have been analyzed. The film deposited at 3 SCCM O-2 flow rate shows the best properties as measured on MOS capacitors. To evaluate the performance of device properties, back-gated bilayer graphene transistors on HfO2 films deposited at two O-2 flow rates of 3 and 20 SCCM have been fabricated and characterized. The transistor with HfO2 film deposited at 3 SCCM O-2 flow rate shows better electrical properties consistent with the observations on MOS capacitor structures. This suggests that an optimum oxygen pressure is necessary to get good quality films for high performance devices.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to the IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND
Keywords: graphene; HfO2; electron beam evaporation; transistor; O-2 flow rate
Department/Centre: Division of Electrical Sciences > Electrical Communication Engineering
Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Division of Physical & Mathematical Sciences > Instrumentation Appiled Physics
Date Deposited: 24 Jun 2014 07:23
Last Modified: 24 Jun 2014 07:23
URI: http://eprints.iisc.ac.in/id/eprint/49319

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