Metal-insulator transition in thin TiOx films

✍ Scribed by C. Vlekken; J. Vangrunderbeek; C. Van Haesendonck; Y. Bruynseraede

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 221 KB
• Volume: 175
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/0921-4526(91)90689-c

✦ Synopsis

Conductivity and electron tunneling measurements are reported for amorphous, oxygen rich Ti films in the vicinity of the Anderson metal-insulator transition. In the metallic films the conductivity varies proportional to ~/-T, while for the insulating films the Mott variable range hopping process is recovered. By reducing the film thickness, a cross-over towards a two-dimensional behavior is observed. For the metallic films a In T divergence of the resistance occurs at the lowest temperatures. On the other hand, the two-dimensional hopping process is affected by the presence of a Coulomb gap. Our tunneling measurements provide us with a quantitative estimate for the reduction of the density of states in metallic films due to the disorder enhanced Coulomb repulsion.