Binary alloy enabled gate work function engineering of nanoscale UTB-GeOI MOSFETs for mixed-signal system-on-chip applications

Abstract

We report the impact of different work function profiles of the gate material on the analog and logic performance of ultra-thin body GeOI MOSFETs at channel length of 30nm based on extensive numerical device simulations. Five such profiles with the work function in the range 4.16–5.05eV are obtained by varying the composition of the binary alloy Ta–Pt. Various device parameters related to analog circuits such as transconductance, transconductance efficiency, output conductance, intrinsic gain and unity-gain cut-off frequency are systematically obtained for devices having different work function profiles. Also evaluated is the logic performance of the device from the delay versus ION/IOFF and IOFF data plots. Our investigations reveal that the output conductance and gain outperform for devices with an increasingly graded work function from the source to the drain while the device with a constant work function yields improved transconductance, transconductance efficiency, unity gain cut-off frequency, and delay.