PROPERTIES OF HYDROGENATED AMORPHOUS-SILICON SUBOXIDE ALLOYS WITH VISIBLE ROOM-TEMPERATURE PHOTOLUMINESCENCE

A systematic investigation of hydrogenated amorphous substoichiometric silicon oxide films (a-SiOx:H) is presented. The a-SiOx:H films were prepared by dc magnetron sputtering and were subsequently annealed at temperatures ranging from 300 to 900 degrees C. No formation of nanocr ystals is detectable either with X-ray diffraction or with Raman scatt ering under any annealing conditions. The infrared spectra of the allo ys are studied in detail. The SiOx films show visible photoluminescenc e (PL) at room temperature similar in spectral shape to that seen for porous silicon. The PL intensity-increases upon annealing up to 500 de grees C before decreasing at higher temperatures. A correlation betwee n the luminescence intensity at 700 mm and an infrared absorption band at 880 cm(-1) is found. The assignment of this absorption band at 880 cm(-1) has been clearified as partially oxygen related via hydrogen-d euterium exchange. Optically detected magnetic resonance reveals the e xistence of triplet excitons with a dipolar radius of 4-5 Angstrom whi ch is associated with the radiative state giving rise to visible lumin escence.