| AVS 61st International Symposium & Exhibition | |
| 2D Materials Focus Topic | Friday Sessions |
| Session 2D+EM+MS+NS-FrM |
| Session: | 2D Materials: Device Physics and Applications |
| Presenter: | NikolaiN. Klimov, National Institute of Standards and Technology (NIST) |
| Authors: | N.N. Klimov, National Institute of Standards and Technology (NIST) S. Le, National Institute of Standards and Technology (NIST) C.A. Richter, National Institute of Standards and Technology (NIST) J. Yan, University of Massachusetts, Amherst E. Comfort, SUNY-University of Albany J.U. Lee, SUNY-University of Albany D.B. Newell, National Institute of Standards and Technology (NIST) |
| Correspondent: | Click to Email |
Graphene, a two dimensional (2D) electronic system with a unique band structure, is a promising material for future electronic devices, especially for electrical metrology [1]. Currently, devices based upon GaAs heterostructures 2D electron gases (GaAs-2DEG) are used to realize a single quantum resistance standard value of (½)h/e2 = 12,906.4035 Ω with metrological accuracy. It is important to realize resistance values over a wider resistance scale to expand the technical relevance of quantum resistance standards.
In the past, attempts have been made by using parallel or series GaAs-2DEG Hall bars to achieve multiple or fractional resistance values of h/e2. However, the difficulties of fabricating ideal contacts and metal interconnects between the Hall bars severely limit the yield of properly operating devices. Graphene, with its ability to create both electron and hole 2D gases on a single Hall bar device without metal interconnects, is an ideal platform to overcome this difficulty [2].
We have fabricated a graphene FET p-n junction device in a Hall bar geometry and experimentally characterized it at large magnetic fields to determine the range of quantized resistance values that can be obtained. The device features two doped polysilicon split gates that are buried in a SiO2 substrate within 100 nm-150 nm from the surface of graphene. The fabrication process achieves an atomically smooth dielectric surface, which is needed to preserve the intrinsic band structure of graphene. Independent voltage control on these gates allows separate tuning of both type and concentration of charge carries in the two parts of graphene conducting channel. In addition, a very narrow 150 nm gap between split gates gives a very sharp junction. Measurement of the sample’s resistance at different gate values and measurement configurations in the quantum Hall regime allows us to fully characterize the device and to obtain multiples or fractions of the resistance value h/e2 . We will show that our experimental results can be explained by the Landauer-Büttiker edge-state transport model with the assumption of a partial mixing at the p-n interface. Potential application of graphene p-n junction devices for resistance standards with a wide range of resistance values other than h/2e2 will be discussed.
References:
[1] A. Tzalenchuk, et al., Nature Nanotech., 5, 186 (2010)
[2] M. Woszczyna, et al., APL, 99, 022112 (2011)