Blue photoluminescence from thermally grown SiO2 on micromachined arrays of silicon planes

SiO2 was thermally grown on arrays of silicon planes obtained from < 110 > substrates by means of micromachining. Blue photoluminescence was observed under pulsed-laser excitation from SiO2 grown on these planes. Experiments revealed that this emission was not affected by the Si/SiO2 interface properties or the silicon thickness, whereas its intensity and spectral features depended on the oxide thickness. Moreover, no detectable luminescence was observed from the oxide grown on unpatterned regions, where a smaller amount of oxide was excited by the laser beam. The photoluminescence disappeared when the oxide was removed.