An unified charge centroid model for silicon and low effective mass III-V channel double gate MOS transistors

In this paper, we have analysed applicability of the charge centroid model used in industry standard BSIM-CMG compact model for III-V multi-gate transistors. It is observed that the existing model is unable to capture the charge centroid behaviour accurately for low effective mass channel materials. The lower effective mass and highly confined geometry enhance the quantum-mechanical effects and the charge centroid shows anomalous behaviour. By using a self-consistent Poisson-Schrödinger solver, the reason behind the anomalies is analysed in detail. A correction to the existing model is proposed to enable its usefulness for low effective mass channel materials. The proposed model is validated by comparing with the the results of a 1D self consistent Poisson-Schrödinger solver. The new model can accurately predict the charge centroid for silicon as well as low effective mass III-V channel double gate transistors of different dimensions and for different bias conditions.