Effect of Laser on Formation of Ge Nanocrystal Embedded in SiO2

We investigate the possibility of using laser for the synthesis of Ge nanocystals in the co-sputtered Ge + SiO2 samples. The laser annealed samples, that were sputtered with ≥ 4 cm2 of Ge attached to the target, exhibited a Raman peak at ~ 290 cm-1. The peak sharpened as the laser beam exposure time increased. However, the peak position was significantly lower than the position of bulk Ge (300 cm-1) peak. It is possible that a structural change in the Ge nanocrystals or stress in the films has caused the peak position to be lower than the bulk Ge value. The photoluminescence (PL) intensity of the laser annealed samples was also considerably weaker as compared to samples that were synthesized by rapid thermal annealing.