Analytical modeling of subthreshold characteristics of ultra-thin double gate-all-around (DGAA) MOSFETs incorporating quantum confinement effects

In this work, analytical models of subthreshold current and subthreshold swing of short channel ultra-thin double gate-all-around (DGAA) MOSFETs including quantum confinement effects have been proposed. The subthreshold current model is presented using Pao-Sah's double integration formula accounting both drift and diffusion components of the current. Quantum effects arising due to 2-D carrier confinement are incorporated in the model to consider the effective carrier density reduction in ultra-thin channel region. A detailed analysis of charge density calculation using density of states (DOS) method is also done. Further, the virtual-cathode potential has been utilised to model the subthreshold swing of the device. The effect of device design parameters like channel thickness, oxide thickness, gate length etc. on subthreshold characteristics has been extensively studied. The model results have been verified by comparing it with the numerical simulation data obtained from 3D device simulator Visual TCAD of Cogenda Int.