Europhys. Lett.
Volume 74, Number 4, May 2006
Page(s) 686 - 692
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 05 April 2006
Europhys. Lett., 74 (4), pp. 686-692 (2006)
DOI: 10.1209/epl/i2006-10018-8

Transport localization in heterogeneous Schottky barriers of quantum-defined metal films

F. Giannazzo1, F. Roccaforte1, V. Raineri1 and S. F. Liotta2

1  CNR-IMM - Stradale Primosole 50, 95121 Catania, Italy
2  STMicroelectronics - Stradale Primosole 50, 95121 Catania, Italy

received 30 January 2006; accepted in final form 10 March 2006
published online 5 April 2006

The nanometric localization of current transport in heterogeneous Schottky barriers was obtained by the combination of the electric field localization at the apex of a biased conductive atomic force microscopy (c-AFM) tip and of the metal films high-resistivity properties. An abrupt increase of the resistivity, modeled by a quantum-mechanical approach, was measured in Au thin films with a thickness below $10\un{nm}$. For Au ultrathin film resistivity, exceeding by two orders of magnitude the bulk value, the nanometric localization of the current transport occurs. This physical effect represents the basic principle of a microscopy approch for two-dimensional Schottky barrier height mapping, which is alternative to conventional ballistic electron emission microscopy (BEEM). A spatial resolution in the order of the tip diameter (10-$20\un{nm}$) is demonstrated by considering the realistic description of the system (physical and geometrical). Schottky barrier inhomogeneities in a Au/4H-SiC system were imaged with an energy resolution better than $0.1\un{eV}$.

73.30.+y - Surface double layers, Schottky barriers, and work functions.
73.50.-h - Electronic transport phenomena in thin films.
07.79.Lh - Atomic force microscopes.

© EDP Sciences 2006