High-quality strain-relaxed Si0.72Ge0.28 layers grown by MBE-UHV/CVD combined deposition chamber

Surface smoothness and fully strain-relaxation Si0.72Ge0.28 virtual layer on Si(100) substrate with an inserted low temperature Ge flat layer is grown by combining molecular beam epitaxy
 system (MBE) and ultrahigh vacuum chemical vapor deposition system (UHV/CVD) in one vacuum chamber. The epitaxial SiGe layer with surface root-mean-square roughness of 1.22 nm and threading dislocation density of 1.5 × 105cm−2 is obtained. The influence of low temperature Ge interlayer on the high quality of SiGe epilayer is investigated. Both of the thermal stability and surface morphology of Si0.72Ge0.28 virtual layer are much better than that of SiGe layer grown by traditional UHV/CVD system.