Image of the Month

January 2013

Imaging of Ti0.87O2 nanosheets using scanning tunneling spectroscopy

institution

Fig. 1. (A) An STM topography scan of Ti0.87O2 nanosheets on Pt(200 nm)/Si of an area of 0.83 um × 0.83 um. Only a faint contrast is observed due to the presence of the nanosheets. (B) di/dz map of the same area from (A). A large contrast in the image reflects a larger difference in di/dz on the nanosheet and Pt/Si surface. Here, tunneling current is 0.5 nA and sample bias voltage is +2.5 V.

Microscope:
RHK Technology UHV 7000

Control System:
RHK Technology SPM 1000 Control System

Credits:
Avijit Kumara, Suresh Kumar C. Palanisamyb, Jelmer M. Botera, Chris Hellenthala, Johan E. ten Elshofb, Harold J.W. Zandvlieta
aPhysics of Interfaces and Nanomaterials, MESA+Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
bInorganic Materials Science, MESA+Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands

Reference:
Applied Surface Science 265 (2013) 201– 204

Abstract:
We report scanning tunneling microscopy (STM) and spectroscopy (STS) measurements on single layer Ti0.87O2 nanosheets deposited on Pt(200 nm)/Si substrates. These nanosheets have a band gap of 3.8 eV and are virtually invisible in conventional STM images. However, an impressive contrast is observed in the di/dz map, which allows for a clear identification of the nanosheets. The di/dz signal is obtained by adding a high frequency, small amplitude modulation to the z-piezo using a lock-in amplifier.