Title :
Scanning tunneling spectroscopy and photoactivation in WO3 gas sensors
Author :
Malagu, C. ; Comini, E. ; Ottini, L. ; Guidi, V. ; Maffeis, T.G.G. ; Martinelli, Giovanni ; Sberveglieri, G. ; Wilks, S.P.
Author_Institution :
Dept. of Phys., INFM, Ferrara, Italy
Abstract :
We collected high resolution scanning tunneling (STM) images on thin films of WO3. This provided information about the morphology and the nanostructure of the samples. The surface gap was then determined through scanning tunneling spectroscopy (STS) and was found to be much narrower than the bulk gap determined via photoluminescence. This effect is a consequence of the high density of surface states in this material. Pinning of the Fermi level due to these states is decreased when the sample is illuminated at low temperature, whereas at high temperature the effect is masked by the high density of free carriers.
Keywords :
energy gap; gas sensors; photoluminescence; scanning tunnelling spectroscopy; surface states; tungsten compounds; Fermi level pinning; WO3; WO3 gas sensors; high density of free carriers; high density of surface states; morphology; nanostructure; photoactivation; photoluminescence; scanning tunneling spectroscopy; surface gap; Atomic force microscopy; Gas detectors; Image resolution; Physics; Scanning electron microscopy; Sociotechnical systems; Spectroscopy; Surface morphology; Surface topography; Tunneling;
Conference_Titel :
Sensors, 2003. Proceedings of IEEE
Print_ISBN :
0-7803-8133-5
DOI :
10.1109/ICSENS.2003.1279073
