DOSE EFFECTS OF CATHODOLUMINESCENCE IN SIO2 LAYERS ON SI

Cathodoluminescence (CL) of thermal SiO2 layers is performed in a digi tal scanning electron microscope (SEM) and wavelength dispersed regist ered by a CCD-camera. The CL-spectrum of SiO2 shows three characterist ic bands at 650 nm (red), 460 Mn (blue) and 285 nm (UV) that all chang e their intensity during the time of electron bombardment. This differ ent excitation dose behaviour of the luminescence bands was investigat ed in a wide range of current densities (10(-5)-10(-3) A cm(-2)) and t emperatures (90-500 K). Some interpretation is made by a model of prec ursor transformation and quenching. The UV and blue luminescence is at tributed to twofold-coordinated silicon in SiO2. Contrary to thermal S iO2 films TEOS-CVD SiO2 shows only the red band which is generally ass ociated with non-bridging oxygen.