Size evolution and photoluminescence of silicon nanocrystallites in evaporated SiOx thin films upon thermal processing

Silicon suboxide thin films have been fabricated by physical vapor depositi on of silicon monoxide in vacuum at controlled oxygen partial pressure. The se films undergo a phase separation into silicon- and oxygen-enriched regio ns upon thermal processing. At temperatures around 900 degreesC, the onset of Si nanocrystallite formation is observed, regardless of film stoichiomet ry. With increasing initial oxygen content of the films, the mean size of c reated nanocrystallites decreases whereas the corresponding photoluminescen ce emission blueshifts. The photoluminescence intensity increases with incr easing annealing temperature up to 1050 degreesC. Upon resonant excitation at low temperatures, the photoluminescence exhibits phonon replica signatur e. Therefore, the emission may be attributed to excitonic recombination in the nanocrystallites.