Evidence of correlation between surface roughness and interface states generation in unstrained and strained-Si MOSFETs

In this paper, we experimentally demonstrate the correlation between the surface roughness and interface states (N_it) generation in unstrained and biaxially-tensile strained Si MOSFETs, for the first time. It is found that s-Si exhibits much a smaller N_it generation rate than Si after FN injection. This more robust SiO₂/Si interfaces in s-Si devices is attributable to the smaller SiO₂/Si interface roughness with lower density of atomic steps. Furthermore, it is newly found that the N_it generation causes roughness-scattering-like mobility reduction, which is less pronounced in s-Si. This new phenomenon is attributable to scattering potential due to spatially non-uniform N_it generation.