New fabrication process for silicon quantum dots by using external laser irradiation

We present an efficient technique for the formation of silicon quantum dots (Si QDs) by exposing a Nd: YAG laser (wavelength = 355 nm) onto amorphous Si film. Primary emphasis is placed on the simple and direct fabrication of the Si QDs without performing any micro or nano-patterning process. The scanned laser irradiation of low power causes localized segregation of as-deposited film by the laser-induced heat, resulting in the fabrication of Si QDs. Observations in scanning electron microscope and atomic force microscope system clearly confirm highly uniform and controllable nanoscale Si QDs in our case. The average size and density of the Si QDs were about 4 nm and 1.5 X 1012/cm2, respectively. In addition, optical and electrical properties of the Si QDs were investigated by photoluminescence and C-V measurements. The experimental results suggest that our new process can lead to very stable optical and electrical devices, with well controllable and reproducible Si QDs.