Effect of channel layer doping on the performance of nanoscale DG MOSFETs

Layer doped double gate MOSFETs (LDDG MOSFETs) with doping on two thin layers near the top and bottom oxide layers of an otherwise intrinsic channel are modeled to obtain the transport characteristics, threshold voltage and leakage current. The variation of these device parameters with a change in doping concentration or doping layer thickness is studied. It is observed that an n-doped layer in the channel reduces the threshold voltage and increases the drive current, when compared with a device of undoped channel. The reduction in threshold voltage and increase in the drain current increase with the level of doping. The leakage current is larger than that of an undoped channel, but less than that of a uniformly doped channel. For a channel with p-doped layer, the threshold voltage increases with level of doping with a reduction in drain current. The doping level of the layers can be used as a tool to adjust the threshold voltage of the device, and the rest of the channel, being intrinsic having high mobility, serves to maintain high drive current in comparison with a fully doped channel. Thus, the doping concentration of the layers can be adjusted to tune the threshold voltage of the device to the desired value, indicating the possibility of easy fabrication of ICs having FETs of different threshold voltages for better power management.