Submicrocrystallites and the Orientational Proximity Effect

High-resolution transmission-electron-microscopic lattice images of 10-nm-thick cross sections of ${10}^3$-nm $a$-Si films deposited at room temperature on clean Si wafers reveal 3-nm clusters, which are orientationally ordered within 80 nm of the substrate-film interface. All previous studies were done in plan view, on films not deposited on clean crystalline substrates, and so did not observe this new effect. Independent evidence suggests that deposition on a clean crystalline substrate generates superior submicrocrystalline morphological order throughout the entire ${10}^3$-nm film.