Resistance and 1/f noise between circular contacts on conductive thin films

¹ Université Lille Nord de France, 59000 Lille, France
² Unité de Dynamique et Structure des Matériaux Moléculaires, Université du Littoral Côte d'Opale, 50 rue F. Buisson, BP 717, 62228 Calais, France
³ Eindhoven University of Technology, Department of Electrical Engineering PT 913, P.O. Box 513, 5600 MB Eindhoven, The Netherlands

Corresponding author: Liang@univ-littoral.fr

Received: 14 October 2010
Accepted: 21 December 2010
Published online: 22 February 2011

Abstract

There is a need to characterize the quality of contacts and the noise properties of new materials deposited or grown as thin films. Poor contacts are interface dominated. Perfect contacts have a negligible interface contribution and there is only a resistance and noise contribution from outside the contact region. The presence of current crowding enhances the resistance and noise contribution. Such contacts are called constriction dominated contacts. The conductive film is characterized by its sheet resistance and normalized conductance fluctuations for a unit surface. The resistance and noise is studied between two circular top electrodes of the same diameter on the conductive. To distinguish between perfect and poor contacts and to characterize the thin film in case of good contacts, we need a set of contacts with different diameters. Models for perfect and poor contacts are investigated. The scaling of resistance and noise with contact radius r is for interface dominated poor contacts: R_i 1/r² and S_Ri 1/r⁶. In contrast, perfect contacts with contact diameter (2r) much smaller than the distance between the centers (2b) show: R_c ln(b/r) and S_Rc 1/r². From the resistance and noise measurements between constriction dominated perfect contacts, the sheet resistance and normalized noise of the thin film are calculated.