Graphene Devices

Mandar Deshmukh
Tata Institute of Fundamental Research / India

Graphene and other 2D materials offer exciting opportunity for electronic and optoelectronic properties individually and as hybrids in combination. The exciting properties include high mobility at room temperature¹, ultra fast photoresponse², high sensitivity to light³, transparency⁴ and interaction with light^4,6,7 and mechanical flexibility^5,6. In addition the property that makes these broad class of 2D materials exciting is the ability to tune of some of these properties. One aspect of tunability is the controlled modification of plasmonic excitation by tuning the density of charges^7,8. Recently it has been shown that the electronic properties of graphene can be modified by creating a superlattice using boron nitride as substrate as this creates a Moiré superlattice^9–11.

Our work¹² extends the idea of superlattices with the use of electrostatic gates to create a periodic potential^13–15 in these 2D materials. These superlattices are similar in spirit to the superlattices studied in the pioneering work done by Esaki and Tsu¹⁶. This can result devices for oscillators and optoelectronic functionality.

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3.   Britnell, L. et al. Strong Light-Matter Interactions in Heterostructures of Atomically Thin Films. Science (2013). doi:10.1126/science.1235547

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5.   Chen, C. et al. Performance of monolayer graphene nanomechanical resonators with electrical readout. Nat. Nanotechnol. 4, 861–867 (2009).

6.   Singh, V. et al. Probing thermal expansion of graphene and modal dispersion at low-temperature using graphene nanoelectromechanical systems resonators. Nanotechnology 21, 165204 (2010).

7.   Fei, Z. et al. Gate-tuning of graphene plasmons revealed by infrared nano-imaging. Nature (2012). doi:10.1038/nature11253

8.   Chen, J. et al. Optical nano-imaging of gate-tunable graphene plasmons. Nature (2012). doi:10.1038/nature11254

9.   Ponomarenko, L. A. et al. Cloning of Dirac fermions in graphene superlattices. Nature 497, 594–597 (2013).

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12. Dubey, S. et al. Tunable Superlattice in Graphene To Control the Number of Dirac Points. Nano Lett. 13, 3990–3995 (2013).

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15. Park, C.-H., Son, Y.-W., Yang, L., Cohen, M. L. & Louie, S. G. Electron Beam Supercollimation in Graphene Superlattices. Nano Lett. 8, 2920–2924 (2008).

16. Tsu, R. & Esaki, L. Tunneling in a finite superlattice. Appl. Phys. Lett. 22, 562–564 (1973).