Abstract
The optimized N 2 O fluence for plasma enhanced chemical vapor deposition (PECVD) growing silicon-rich substoichiometric silicon oxide (SiO x ) with buried Si nanocrystals is demonstrated. Strong room-temperature photoluminescence (PL) at 550-870 nm has been observed in SiO x thin films grown by PECVD with N 2 O fluence varying from 105 to 130 seem. After annealing from 15 to 180 min, a 22-nm-redshift of the PL has been detected. The maximum PL intensity is observed for the 30-min annealed SiO x growing at N 2 O fluence at 120 seem. Larger N 2 O fluence and longer annealing time causes a PL blueshift by 65 nm and 20 nm, respectively. Such a blueshift is attributed to shrinkage in the size of the Si nanocrystals under the participation of dissolved oxygen atoms from N 2 O. The (220)-oriented Si nanocrystals with radius ranging from 4.4 to 5.0 nm are determined. The luminescent lifetimes lengthens from 20 μs to 52 μs as the nc-Si size extends from 4.0 to 4.2 nm. Optimal annealing times for SiO x preparing at different N 2 O fluences and an optimum N 2 O fluence of 120 seem are reported. Serious oxidation effect at larger N 2 O fluence condition is observed, providing smaller PL intensity at shorter wavelengths. In contrast, the larger size nc-Si will be precipitated when N 2 O fluence becomes smaller, leading to a weaker PL at longer wavelength. These results provide the optimized growth condition for the Si-rich SiO 2 with buried Si nanocrystals.