Dielectric confinement and fluctuations of the local density of state in the source and drain of an ultra scaled SOI NMOS transistor

We fabricated SOI nanowire MOSFETs with a very small channel volume and few dopants between the highly doped source and drain. The ionization energy of these isolated As dopants can be extracted. We found a much higher energy than calculated value for As in bulk Si. This enhancement is due to the so-called dielectric confinement, because of the proximity of the buried oxide. Transport through this single dopant also enables probing the fluctuations of local density of states in the contacts.