Speaker: Neil Johnson
Location: Physics 127
Time: 3:30 May 19 2015
Abstract: Graphene is one of the most celebrated and intensively studied materials of the last decade. Its potential uses include transparent conductors, filtration, optoelectronics, photovoltaics and as a semiconductor for electronic devices. However, its implementation as a semiconductor is hampered by its utter refusal to stop conducting, even in the absence of an external field or doping. This has a deleterious effect on the ON/OFF ratios of graphene-based devices, and as such none have ever been made that are able to outperform current bulk silicon devices.
Silicene, the silicon-based analogue to graphene, is expected to have a number of significant advantages over its carbon-based cousin. It should have a tuneable bandgap, an ambipolar field effect and possibly even spin-polarization all from the application of an external gating voltage. Clearly, silicene is much, much better than graphene could ever hope to be. However, one slight, minor stumbling block in the implementation of freestanding monolayers of silicene is that nobody has been able to make them yet, and it’s been questioned whether or not they can actually exist. Instead, silicene has only been observed while stuck to growth substrates, and until recently it was unclear how this would affect the properties of the material. In this seminar I will briefly outline the history of 2D materials, the development of silicene and my research into silicene grown on the Ag(111) surface.