High-quality optical and epitaxial Ge films formed by laser evaporation

High-quality thin films of Ge were deposited by pulsed laser evaporation of molten Ge. Films deposited on 300 °C substrates showed very smooth morphologies and single-crystal grain structures. Energetic ions in the vapor stream, generated by the laser-induced plasma, were observed to affect nucleation and bulk-film growth. Films deposited on ambient temperature substrates by laser evaporation were denser, harder, and exhibited higher values of refractive index and lower levels of intrinsic stress than the films deposited by thermal evaporation.