THIN-FILM MECHANICALLY CONTROLLABLE BREAK JUNCTIONS

An adaptation of the mechanically controllable break junction techniqu e using thin metallic films to create point contacts and tunnel juncti ons is presented. The junctions that are created using this very simpl e method are extremely stable, and can easily be adjusted from rather large point contacts (R approximate to 0.1 Omega) to high-resistance ( 10(10) Omega) tunnel junctions. The electrodes can be kept very clean by breaking the sample in ultrahigh vacuum or in a very pure helium at mosphere at 1-4 K. Point-contact spectra of good quality were measured for contacts of 0.1-500 Omega. For very small contacts, the expected steplike increase of junction resistance with decreasing contact size was observed, with a jump to tunneling behavior occurring at resistanc es of 12-14 k Omega. (C) 1996 American Institute of Physics.