Enhanced emission in the three-level system of Si and Ge nanostructures

Enhanced mission peak near 700 nm is observed on the silicon quantum dots (QDs) embedded in Si amorphous film and the peak near 1100 nm occurs on the silicon nanolayer, which have the emission characteristics of direct band-gap, such as the thresholds effect and the supper-line increasing effect in intensity with pumping in our experiment. It is interesting that the Si QDs embedded in nanosilicon layer are prepared by using pulsed laser deposition (PLD) method after annealing. In the same way, the peak near 900 nm on the Ge QDs and the peak near 1500 nm on the Ge nanolayer are measured in the PL spectra. It is very interesting that the sharper peaks with multi-longitudinal-mode occur in the Si and Ge nanolayers with the super-lattice on SOI in which the QDs are embedded. An emission model for Si and Ge laser on silicon chip with QDs pumping has been provided to explain the experimental results.