Roughening behavior in Si/SiGe heterostructures under O2+ bombardment

The roughening behavior of 10-layer Si/SiGe heterostructures under 1 keV O 2 + sputtering at 44° incidence angle is accounted for using a modified MRI model. The MRI curve-fitted roughness parameters obtained from the Ge depth profiles are compared with the root-mean-square roughness from AFM scans of crater bottom topography. This comparison indicates that the surface roughening behavior during ion sputtering can be reasonably described by the MRI model. The MRI curve-fitted roughness parameter is found to be systematically larger than the AFM roughness values, and this is explained by additional roughness contributions from mixing straggling and interface roughness during the surface morphology evolution under O 2 + sputtering.