Preferential orientation in bismuth thin films as a function of growth conditions

Abstract

Bismuth thin films are known to exhibit interesting properties that can be explored for new applications such as optical or electrical sensors and thermoelectric devices. Due to the large anisotropy of the electronic band structure of Bi, its conductivity and optical functions are largely dependent on the preferred orientation obtained for the polycrystalline thin films, which are determined by the deposition system and the parameters.In this study we report on the growth of bismuth thin films deposited by various deposition methods, all of them starting from the vapor phase but with different energies associated to the impinging species: thermal and electron beam evaporation, direct and alternating current magnetron sputtering, and pulsed laser evaporation. It is shown that the texture developed in Bi thin films follows a competitive growth texture in which the crystallographic planes with lower surface energy are favored and this process is dominant unless enough energy is supplied either by substrate heating or high energy bombardment.