Investigation of Si/SiGe/Si heterostructure implanted by H ion and annealed in vacuum and dry O2 ambient

Abstract

The 20-nm-thick Si cap layer/74-nm-thick Si0.72Ge0.28 epilayer/Si heterostructures implanted by 25keV H+ ion to a dose of 1×1016cm−2 were annealed in ultra-high vacuum ambient and dry O2 ambient at the temperature of 800°C for 30min, respectively. Rutherford backscattering/ion channeling (RBS/C), Raman spectra, high-resolution X-ray diffraction (HRXRD) and atomic force microscopy (AFM) were used to characterize the structural characteristics of the Si0.72Ge0.28 layer. Investigations by RBS/C demonstrated that the crystal quality of the Si/Si0.72Ge0.28/Si heterostructure sample implanted by 25keV H+ in conjunction with subsequent annealing in dry O2 ambient is superior to that of identical sample annealing in ultra-high vacuum ambient. The less strain relaxation of SiGe layer of the Si/Si0.72Ge0.28/Si heterostructures implanted by H ion and annealed in dry O2 ambient at the temperature of 800°C for 30min could be doublechecked by Raman spectra as well as HRXRD, which was compared with that in an identical sample annealed in ultra-high vacuum ambient for identical thermal budget. In addition, the SiGe layer of the H-implanted Si/SiGe/Si heterostructural sample annealed in dry O2 ambient accompanied by better crystal quality and less strain relaxation made its surface morphology superior to that of the sample annealed in ultra-high vacuum ambient at the temperature of 800°C for 30min, which was also verified by AFM images.