Tuning of Threshold Voltage in Silicon Nano-Tube FET Using Halo doping and its Impact on Analog/RF Performances

In this paper, a novel method is proposed for the first time to achieve multiple threshold voltage (VT) for Silicon Nanotube FET. Using TCAD simulator, it is shown that threshold voltage can be varied by tuning the halo doping and tube diameter of Silicon Nanotube FET. The typical method to attain multiple threshold voltages is to select the pertinent gate work-function for individual devices. But this is not practically feasible due to the difficult process complexity. In this work, the tuning of halo doping and nanotube diameter can be elected to provide three possible values of VT at 14-nm technology node. Furthermore, short-channel effect like Drain Induced Barrier Lowering (DIBL) is also found to be reduced with HALO doped region at source side. It is also observed that the threshold voltage decreases while increasing the tube diameter. Moreover, HALO doping at drain side is found showing a significant improvement in analog/RF performances of the device which eventually makes the device more suitable for radio-frequency integrated circuit applications.