Formation of Si nanocrystals by heavy ion irradiation of amorphous SiO films

We studied the structural transformations of a-SiO thin films caused by swift heavy ion irradiation at room temperature. Rutherford backscattering spectroscopy, nuclear reaction analysis, transmission electron microscopy and infrared absorption spectrometry have been used in combination to investigate the changes induced by ion irradiation. We show that the homogeneous monoxide is transformed according to the macroscopic reaction: 2SiO→Si+SiO2. Each ion perturbs a large area (approximately 10-30 nm diameter). 2-3 nm diameter Si clusters are formed inside the track core. A broad photoluminescence at ∝600 nm is also detected in the irradiated films. This visible light emission is associated with the formation of the perturbed zone. (orig.)