[Phys-seminars] 2011-11-29 Lasers Seminar - TODAY!!!

barmash at bgu.ac.il barmash at bgu.ac.il
Tue Nov 29 08:54:11 IST 2011

Lasers Seminar - TODAY!!!

  DATE: 29-11-2011

  TIME: 3:30pm (Tue)

  PLACE: Physics building (#54) room 207

Nanoscale Electronic Measurements of Individual Semiconductor Nanowires 

Y. Rosenwaks*, Dept. of Physical Electronics, School of Electrical Engineering, Tel-Aviv University, Israel

The large surface-to-volume ratio in semiconductor nanowires increases the importance of their sub-bandgap traps and surface states in determining various electrical properties.  In addition, the potential of the metal nanocatalyst to contaminate vapor-liquid-solid (VLS) grown semiconductor nanowires has been a long-standing concern, since the most common catalyst material, Au, is known to induce deep gap states in several semiconductors.  

We use Kelvin probe force microscopy (KPFM) to image individual deep acceptor type trapping centers close to the surface of undoped Si nanowire, grown with an Au catalyst.  We also report on quantitative measurements of surface states energy distribution and concentration in individual VLS grown InAs nanowires. The wurtzite InAs nanowires (NWs) were grown by Au-assisted VLS molecular-beam-epitaxy (MBE) and contain some stacking faults.  It is found, in similarity to bulk InAs, that a large concentration of donor-type surface states induce the well known electron accumulation. Nevertheless, due to the low diameter of the nanowires, the electron accumulation and Fermi level pinning takes place within the entire wire.
E. Koren, N. Berkovich, and Y. Rosenwaks,  Nanoletters, 10, 1163-1167, (2010).
E.Koren, J.K. Hyun, U.Givan, E. Hemesath, L.J. Lauhon and Y.Rosenwaks,  Nanoletters, 11, 183-7, (2011).
E. Koren, G. Elias, A. Boag, E. Hemesath, L.J. Lauhon and Y.Rosenwaks,  Nanoletters, 11, 2499-2502, (2011).  

* This work is in collaboration with E. Koren, I. Amit, E. Halpern, G. Elias, and A. Boag Tel-Aviv University, L.J. Lauhon Northwestern University, and H. Shtrikman Weizmann Institute. 

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