Growth and Luminescence of SiGe Self-organized Dots

It is found that the SiGe alloy self-organizes into uniform quantum dots embedded in the silicon layer during the growth of strained SiGe/Si rnultilayers on a Si (001) substrate by molecular beam epitaxy. The energy of photoluminescence from the quantum dots is higher than the indirect band-gap of Si, and the luminescence of the quantum dots exceeds that of quantum well by three orders of magnitude. This can be attributed to an indirect-to-direct band-gap conversion in the SiGe dots.