Data and Time May 11 , 2010, 3:00-4:15 PM
Location Sanford Fleming Building (SF), Room B560
Host Alex Wong

High temperature, ultra-high sensitivity electrometry using InAs nanowire field effect transistors

Joe Salfi

The Edward S. Rogers Sr. Department of Electrical and Computer Engineering (Photonics)


Electrometry - measuring small quantities of charge - is at the heart of solid state technologies such as low power electronic memories and gas and biochemical sensors, as well as many experimental systems exploring quantum information science in the solid state.  While it is known that a single charge can completely quench light emission from a semiconductor nanowire (NW) or nanocrystal, as it does for a single molecule, little is known about its effect on the conductance of NWs, which have both dielectric and electronic confinement.  We have experimentally demonstrated that stochastic capture and emission of a single electron by a trap site (e.g. defect) on the surface of an InAs NW field effect transistor (FET) routinely produces a potential barrier of sufficient strength to change the NW's state from metallic to insulating.   Experiments elucidating the electronic transport in InAs NWs and properties of their defects will be discussed.  Analysis of signal to noise ratio demonstrates ultra-high charge detection sensitivities of 5e-5 e/Hz^1/2 (6e-5 e/Hz^1/2) at ~ 30 K (~ 200 K) for 30 nm diameter InAs NWFETs.  NWFET-based electrometers could drastically reduce or completely eliminate the cost and complexity barriers of cryogenic cooling (to 4 Kelvin) required for traditional ultra-high-sensitivity single-electron-transistor (SET) based electrometers.  Applications such as single electron memories, and gas and biochemical sensors with unprecedented sensitivity and speed are envisioned.  NWFETs are also interesting candidates for high temperature, high-speed qubit state readout. 


Joseph Salfi obtained a bachelor of applied science (BASc) degree inComputer Engineering (Physics Option) from University of Waterloo in 2004. Since then, he has been a PhD candidate in Electrical Engineering in the Photonics Group and Centre for Advanced Nanotechnology at the University of Toronto under the supervision of Prof. Harry Ruda.  His research interests are transport of charge and spin as well as optics in semiconductor nanostructures, applied to design of future nano-electronics, opto-electronics, and quantum information technologies.