凯发

Starting Time：2014-09-01 09:00:00

Ending Time：2014-09-03 17:00:00

Location：

Introduction：

1D graphene nanoribbons have tunable electronic bandgaps, thereby enabling graphene electronic/optoelectronic applications. We have demonstrated both bottom-up and top-down methods for fabricating graphene nanoribbons. First, we present surface-assisted bottom-up fabrication of atomically precise armchair graphene nanoribbons (AGNRs) with predefined widths, namely 7-, 14- and 21-AGNRs, on Ag(111) as well as their spatially resolved width-dependent electronic structures [1]. Second, we demonstrate the top-down fabrication of an intramolecular junction by the controllable unzipping of single-walled carbon nanotubes, combining a graphene nanoribbon and single-walled carbon nanotube in a 1D nanostructure [2]. This junction shows strong gate-dependent rectifying behavior, and we demonstrate the use of the junction in prototype directionally dependent field-effect transistors, logic gates and high performance photodetectors.

2D transition metal dichalcogenides (TMDs, e.g. MX₂, M = Mo, W; X = S, Se, Te) are promising alternatives to graphene, as they can have a direct bandgap enabling electronic and optical applications. We use high resolution STM/STS to study the atomic structure and intrinsic electronic properties of MoS₂ layers (mono-, bi-, tri-) directly deposited on HOPG substrates by CVD [3]. We also investigate highly crystalline and large-area tungsten diselenide (WSe₂) monolayers on sapphire grown by CVD [4]. The monolayer films display strong photoluminescence, opening up potential applications in optoelectronics. We fabricate monolayer WSe₂ transistors with ON/OFF current ratio of up to 10⁹, and mobility larger than 7.3cm²/Vs. 

[1] H. Huang, D.C. Wei, J.T. Sun, S.L. Wong, Y.P. Feng, A.H. Castro Neto, A.T.S. Wee, Scientific Reports 2, 983 (2012).

[2] D.C. Wei, L.F. Xie, K.K. Lee, Z.B. Hu, S.H. Tan, W. Chen, C.H. Sow, K.Q. Chen, Y.Q. Liu, A.T.S. Wee, Nature Communications 4, 1374 (2013).

[3] Y.L. Huang et al., submitted.

[4] W.J. Zhang et al., submitted.

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