Light-emitting silicon films fabricated by neutral cluster deposition and subsequent high-temperature annealing

A neutral Si-cluster deposition apparatus has been constructed for preparing Si films whose light-emitting features are studied under various deposition and subsequent annealing conditions. After the setup and operation of the apparatus are described, examples are shown in which efficient light-emitting amorphous SiO2 (a-SiO2) films with Si nanocrystals embedded in them can be prepared on single crystal Si substrate by the deposition with and without thin O2 gas admitted and the subsequent high-temperature annealing in an evacuated chamber. These thin films as well as unannealed films were comparatively observed by atomic force microscopy and high-resolution transmission electron microscopy, and analyzed by means of X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence (PL) and FTIR-attenuated total reflection measurements. All the PL curves of the annealed samples have a peak around 600 nm, almost the same position as the a-SiO2 films have, but their PL intensity increases dramatically, approximately seven times larger than that of unannealed samples. It is suggested that the source of the luminescence is due to the electron-hole recombination in the a-SiO2/Si interfacial a-SiOx (x < 2) layer.