Design insights into RF/analog and linearity/distortion of spacer engineered multi-fin SOI FET for terahertz applications

Multi-fin devices are the most reliable option for terahertz (THz) frequency applications at nano-regime. In this work impact of spacer engineering on multi-fin SOI FET performance is evaluated by invoking single low-k (Air), high-k (Si₃N₄, HfO₂), and hybrid dual-k (Air + Si₃N₄) spacer in the underlap section at nano-regime. The simulation study reveals that the high-k (HfO₂) spacer gives a higher switching ratio (I_ON/I_OFF) in the order of ~10⁷, subthreshold swing (SS) = 72 mV/dec, drain induced barrier lowering (DIBL) = 22.14 mV/V and quality factor (Q) = (Formula presented.) /SS = 0.16 μS-dec/mV. Furthermore, to measure the suitability of the device for high frequency applications various analog/RF parameters are studied. The high-k (HfO₂) spacer dominates DC and analog performance, whereas the low-k (Air) spacer dominates the RF domain with (Formula presented.) = 1.26 THz, GBW = 0.251 THz, TFP = 29 THz range, and with smaller intrinsic delays. Hybrid dual-k spacer (Air + Si₃N₄) outperforms in terms of gain (A_V) and output resistance ((Formula presented.)). The Air spacer exhibits lower dynamic power of 2.09 aJ/μm and power consumption of 1.04 aJ/μm. The linearity metrics for multi-fin SOI FET parameters like (Formula presented.), (Formula presented.), HD1, HD2, THD, and VIP2 are also studied. The Air spacer followed by hybrid spacer outperforms in linearity, and harmonic distortion components and ensures its potential for RF applications at nano-regime.