Thermal-hydrogen promoted selective desorption and enhanced mobility of adsorbed radicals in silicon film growth

Car-Parrinello simulations and static density-functional theory calculations reveal how hydrogen promotes growth of epitaxial, ordered Si films in plasma-enhanced chemical vapor deposition at low-temperature conditions where the exposed Si(001)-(2×1) surface is fully hydrogenated. Thermal H atoms, indeed, are shown to selectively etch adsorbed silyl back to the gas phase or to form adsorbed species which can be easily incorporated into the crystal down to T∼200°C and start diffusing around T∼300°C. Our results are well consistent with earlier experiments. © 2008 The American Physical Society.