Growth of Silicon Nanocrystal Dots with High Number Density by Ultra-High-Vacuum Chemical Vapor Deposition

Si nanocrystal growth using an amorphous Si (a-Si) layer pre-deposited on a SiO 2 surface has been performed by ultra-high-vacuum chemical vapor deposition (UHV-CVD). It has been shown that high-density Si nanocrystals are formed by Si 2 H 6 irradiation on to an a-Si surface and that Si atoms supplied from the a-Si layer contribute to the growth of Si nanocrystals. By changing the thickness of the a-Si layer, the number density and size of Si nanocrystals can be controlled systematically. A number density of 1.0×10 12 cm -2 and an average diameter of 9.1 nm were achieved for Si nanocrystals on the SiO 2 /Si substrate in the case of using a 0.3-nm-thick a-Si layer. Si nanocrystals were successfully buried in a SiO 2 matrix by post deposition processes and their diameters were found to range from 6 to 10 nm.