Performance Analysis of Dual Material Gate Junctionless Nanowire Transistor

Abstract

For the incessant progress of CMOS devices, scaling technology has become a major key. Due to the scaling of devices, they are facing some challenges such as short channel effects, difficulty in carrier transport through the channel of the transistor, increased leakage current and difficulty in small junction formation etc. Excellent performance and high-speed devices required high value of the figure of merit (FOM), high transconductance (gm), small conductance of drain, high cut-off frequency (fT ). To achieve excellent performance and high speed, a number of devices are proposed with improved designs using gate length reduction, split gate design (Gate Engineering) etc. In bulk MOSFETs due to scaling control of gate over the channel reduces, this gives rise to SCEs.
To overcome these problems multi-gate transistors are proposed. Particularly in case of conventional multi-gate transistors at lower technology nodes doping at different regions is a cumbersome task. So multi gate junctionless devices are proposed. Here a novel technique is used to further improve the performance of the proposed device.
Dual Material Gate Junctionless Nanowire Transistor (DMG-JNT) has been proposed with high standard gate controllability. This structure takes the advantages of difference in gate material workfunction in such a way that near the source threshold voltage is higher than the threshold voltage near the drain, which results in improved charge carrier transport from the source side to the drain side. Effects of dual gate material workfunction difference and gate length variation on, on current (Ion), off current (Iof f ), ratio of Ion/Iof f , gain bandwidth product (GBW), 1dB-compression point, cut-off frequency (fT ), transconductance generation factor (TGF), E-field, surface potential, electron velocity and electron mobility etc. are studied and compared with the single material gate junctionless nanowire.
Later on, to investigate the small signal behaviour of the DMG-JNT with respect to SMG-JNT S-parameter measurement method has been used at RF and microwave frequencies. For this reflection and transmission coefficients are examined and compared with SMG-JNT. Also, the effects of workfunction difference and gate length variation studied on DMG-JNT structure. DMG-JNT is owing to improved performance in comparison with SMG-JNT.