We studied the influence of substrate temperature on the structures and properties of silicon oxide (SiOx) nanostructured films formed by pulsed-laser deposition (PLD) in oxygen. After laser ablation, the single crystal Si(100) target is converted to a polycrystalline structure due to the melting and re-crystallization. The as-deposited SiOx nanostructured films show large particles (i.e. droplets) which have the same high crystallinity as the Si(100) target but weak photoluminescence (PL) emission. The strong PL at 1.6-1.9 eV is from the amorphous-like background film rather than from the crystalline droplets. With increasing excitation power, the PL peak shows very small blue shift and PL intensity saturates, which can be explained by quantum confinement model. With increasing substrate temperature from room temperature, both the PL band and the optical band gap continually red shift due to the increased Si concentration. After annealing at 800 C, both the PL and optical absorption are enhanced. Combined with the progressive PL red shifts of the SiOx films by plasma-enhanced chemical vapor deposition (PECVD) with increasing Si concentration, the results strongly support the quantum confinement theory.
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