Structural evolution of bismuth thin films with decreasing substrate temperature during deposition

Determine the evolution of the crystallographic structure and microstructure of bismuth thin films during thermal evaporation as the substrate temperature decreases from room temperature toward cryogenic values, including how preferred orientation, phase, and morphology change between room-temperature deposition and quench-condensed deposition.

Background

Bismuth thin films exhibit markedly different textures and morphologies when deposited at room temperature versus at cryogenic temperatures. Prior work typically compared room-temperature films to those deposited below 25 K, leaving the detailed evolution with decreasing substrate temperature insufficiently characterized.

This study investigates films deposited at 296 K and at 77 K across multiple substrates and observes shifts in preferred orientation and grain size, motivating a clearer understanding of the structural changes that occur as substrate temperature is lowered during growth.