Structural and Physical Properties of Ultrathin Bismuth Films

Abstract

Bismuth films are interesting objects for research because of the many effects occurring when the film thickness is less than 70 nm. The electronic band structure changes significantly depending on the film thickness. Consequently, by changing the film thickness, it is possible to control the physical properties of the material. The purpose of this paper is to give a brief description of the basic structural and physical properties of bismuth films. The structural properties, namely, morphology, roughness, nanoparticle size, and texture, are discussed first, followed by a description of the transport properties and the band structure. The transport properties are described using the semi-metal–semiconductor transition, which is associated with the quantum size effect. In addition, an important characteristic is a two-channel model, which allows describing the change in resistivity with temperature. The band structure of bismuth films is the most interesting part due to the anomalous effects for which there is still no unambiguous explanation. These effects include anomalous spin polarization, nontrivial topology, and zone changes near the edge of the film.