Strong visible photoluminescence in amorphous SiO_x and SiO_x:H thin films prepared by thermal evaporation of SiO powder

摘要

Amorphous SiO_x and SiO_x:H films were prepared by thermal evaporation of SiO powder in ultrahigh vacuum or under a flow of hydrogen ions onto silicon substrates maintained at 100 °C. Photoluminescence (PL) can be seen in 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 spectrometry. The PL is attributed to the quantum confinement of excitons in a-Si clusters embedded in the a-SiO_x matrix. Our results demonstrate that oxygen creates an efficient potential barrier and no further passivation by hydrogen is necessary.