Effect of mismatch-induced stress on the growth and electronic structure properties of bismuth films

Abstract

Bismuth (Bi) films, characterized by a narrow bandgap and high carrier mobility, hold significant potential for applications in electronic and spintronic devices. However, the microscopic mechanisms by which mismatch-induced stress influences film growth and electron-transport properties remain poorly understood. In this study, Bi films were fabricated by molecular beam epitaxy (MBE) through heterogeneous epitaxy on MgO single-crystal substrates. The effects of substrate temperature and the deposition rate on film growth were systematically optimized. Crystal structure analysis and lattice mismatch calculations were performed using reflection high-energy electron diffraction (RHEED). The critical thickness of the film was determined by combining the stress state observed in situ by RHEED and analyzing XRD data. Resistance-temperature characterization revealed a gradual transition from surface-state-dominated to bulk-state-dominated conduction as the film thickness increased. Stress relaxation induced modifications in the electronic band structure of Bi, resulting in shifts in the peak resistance temperature (T_top) of resistance-temperature curves. These results provide valuable insights into the influence mechanism of stress on the electronic structure of Bi's (00l) surface.