Surface Evolution During Low Temperature Epitaxial Silicon Growth by Hot-Wire Chemical Vapor Deposition: Structural and Electronic Properties

We report the surface and structural evolution of hotwire chemical vapor deposited (HWCVD) crystalline Si thin films with temperature, thickness, and hydrogen dilution and the resulting growth regimes and electronic properties. We focus on a low silane partial pressure regime that leads to epitaxial growth with a polycrystalline, rather than an amorphous transition. Using scanning electron microscopy and atomic force microscopy, we find the relationship between the deposition conditions and the evolution of the surface roughness. Increasing the hydrogen dilution changes the kinetic growth regime from growth predominantly from the wire to shadow-dominated etch and finally to a regime dominated by desorption and re-deposition of growth species. Transitions between these kinetic regimes are the dominant factors governing the epitaxial-polycrystalline transition in low temperature HWCVD growth along with their electronic properties