Abstract
Silicon the material per excellence for electronics is not used for sourcing light due to the lack of efficient light emitters and lasers. In this talk, I will discuss the physical reasons why silicon is not a laser material and some approaches to make it lasing. I will start with bulk silicon, then I will discuss silicon nanocrystals and Er/sup 3+/ coupled silicon nanocrystals where significant advances have been done in the past and can be expected in the near future. I will conclude with an optimistic note on silicon lasing. A summary of this talk can be found in L. Pavesi "Routes towards a silicon-based laser" Materials Today 8(1) (January 2005) pag. 18-25.