Strong visible photoluminescence in amorphous SiOx and SiOx : H thin filmsprepared by thermal evaporation of SiO powder

Amorphous SiOx and SiOx:H films were prepared by thermal evaporation of SiO powder in ultrahigh vacuum or under a flow of hydrogen ions onto silicon s ubstrates maintained at 100 degrees C. Photoluminescence (PL) can be seen i n the visible range with the naked eye on the as-deposited samples without post-treatments. Composition and structure investigations were performed by infrared and Raman spectrometry experiments on films annealed at different temperatures. Hydrogen and oxygen bonding was studied by infrared spectrom etry. The PL is attributed to the quantum confinement of excitons in a-Si c lusters embedded in the a-SiOx matrix. Our results demonstrate that oxygen creates an efficient potential barrier and no further passivation by hydrog en is necessary. (C) 1999 Elsevier Science B.V. All rights reserved.