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SUMMARY:(SP Wednesday Workshop) - Contacting low numbers of nano-crystals 
 using graphene - Mr Joel Fruhman\, University of Cambridge
DTSTART:20140604T131500Z
DTEND:20140604T141500Z
UID:TALK52470@talks.cam.ac.uk
CONTACT:Teri Bartlett
DESCRIPTION:In order to investigate isolated nano-crystals electronically 
 it is necessary to make good electrical contact with both source and drain
  leads. The typical size of\, for example\, isolated semiconductor quantum
  dots\, along with their outer capping ligands makes this a difficult task
 . But this has been achieved as early as the mid-late 90’s\; most succes
 sfully using molecular self-assembly [1]. Since then a range of electronic
  functions based on single electron transfer have been demonstrated such a
 s transistors\, switches and rectifiers\; all fabricated with a bottom up 
 approach [2]. However\, almost all of these devices can only be built on a
 n individual basis or in low numbers. This is generally thought to be the 
 largest inhibitor to the uptake of such technologies into the semiconducto
 r industry. Graphene with its unique mechanical and electrical properties 
 may facilitate the parallel fabrication of such devices [3].\n\nIn this ta
 lk progress on a novel\, scalable\, single electron device is reported. A 
 monolayer of nano-crystals is sandwiched between a gold bottom electrode a
 nd a CVD-grown graphene layer placed on top. Being a strong\, continuous c
 onducting sheet\, the graphene is capable of electrically contacting the n
 ano-crystals without shorting through the potential pin-holes in the monol
 ayer. Previous work performed in the group last year\, that found no evide
 nce of coulomb blockade but observed a negative differential resistance\, 
 is assessed for its successes and pitfalls. This leads to an understanding
  of the latest iterations of the device and their designs. Here a reactive
  ion plasma etch process allows for the minimisation of coincident graphen
 e/Au boundaries and hence lowers the number of electrically contacted nano
 -crystals. Current experimental processes are discussed and the long term 
 goals for the project are outlined.\n\n \n[1] “An approach to electrical
  studies of single nanocrystals” – Applied Physics Letters 68\, 2574 (
 1996)\nDavid L. Klein and Paul L. McEuen\, Janet E. Bowen Katari\, Richard
  Roth\, and A. Paul Alivisatos\n \n[2] “Nanogap electrodes” – Advanc
 ed materials Vol 22 pp. 286-300 2010\nTi Li\, W Hu\, D Zhu\n \n[3] “Grap
 hene Veils and Sandwiches” - Nano Lett.\, 2011\, 11 (8)\, pp 3290–3294
 \njong Min Yuk \, Kwanpyo Kim \, Benjamín Alemán \, William Regan \, A. 
 Paul Alivisatos\n 
LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Department of Physics
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