Growth mechanism of GeSi quantum rings on Si [001]

Abstract

This study performs experiments on ultrathin Si capping on Ge quantum dots at varying growth temperature to clarify the growth details of GeSi quantum rings on Si [001]. Results show that at a lower temperature of 400/spl deg/C with several angstroms thick Si capping, the shape of dots remains domed, but at a higher temperature of 640/spl deg/C, the shape changes from dome to pyramid. This phenomenon shows that the shape transition is highly dependent on temperature and Ge atom diffusion and Ge atom segregation play an important role in quantum ring formation. This is confirmed by the results of grazing incidence X-ray diffraction.