THE ORIGIN OF PHOTOLUMINESCENCE FROM THIN-FILMS OF SILICON-RICH SILICA

We have carried out a study of the photoluminescence properties of sil icon-rich silica. A series of films grown using plasma enhanced chemic al vapor deposition over a range of growth conditions were annealed un der argon at selected temperatures. Photoluminescence spectra were mea sured for each film at room temperature and for selected films at cryo genic temperatures. The photoluminescence spectra exhibit two bands. F ourier transform infrared and electron spin resonance spectroscopies w ere used to investigate bonding and defect states within the films. Th e data obtained strongly suggest the presence of two luminescence mech anisms which exhibit different dependencies on film growth conditions and postprocessing. We make assignments of the two mechanisms as (1) d efect luminescence associated with oxygen vacancies and (2) radiative recombination of electron-hole pairs confined within nanometer-size si licon clusters (''quantum confinement''). (C) 1996 American Institute of Physics.