Impurity doping effects on impurity band structure modulation in two-dimensional n+ and p+ Si layers for future CMOS devices

Abstract

We experimentally studied the effects of n+ and p+ dopant atoms on the band structure modulation in two-dimensional (2D) Si layers for a wide range of dopant density N by the photoluminescence (PL) method. The bandgap EG of both n+ and p+ 2D-Si strongly depends on N, and decreases with increasing N, which is attributable to the EG narrowing effects δEG even in 2D-Si. However, δEG in the doped 2D-Si is much smaller than that in 3D-Si and depends on whether the dopant is donor or acceptor. We introduce a simple model for the small δEG, considering the impurity band structure modulation in heavily doped 2D-Si. As a result, we can estimate source/drain dopant density dependence of a built-in potential of pn junction in a 2D-Si layer for CMOS devices.