How quantum effects and unintentional doping affect the threshold voltage of narrow-width SOI devices

A 50 nm gate length narrow-width SOI device structure has been studied using an in-house 3D ensemble Monte Carlo particle-based device simulator. We find a threshold voltage increase with decreasing channel width due to lateral quantum-mechanical size-quantization effect. We also find that the presence of even a single impurity in the channel region of the device (unintentional doping) gives rise to significant threshold voltage fluctuations based upon its location. In summary, quantum effects and short-range Coulomb interactions must be properly accounted for when investigating nanoscale devices.