Modelling of threshold voltage adjustment in fully depleted double gate (DG) SOI MOSFETs in volume inversion to quantify requirements of gate materials

Abstract

An analytical model is developed for volume inversion in DG SOI MOSFETs to study the impact of silicon film thickness, work function difference between gate and substrate, and gate voltage on electric potential, electron density and sheet density of mobile charges. The proposed model is extended to predict the threshold voltage of devices with different gate materials and quantifies the gate material requirements of symmetric self-aligned DG MOSFETs. A limiting criterion is developed on doping level and film thickness to ensure the occurrence of volume inversion in fully depleted DG SOI MOSFETs. Close proximity with simulated results confirms the validity of the present model.