Performance Comparison Between Si and Ge pDG-FETs for Different Channel Lengths Based on Hole Transport Simulation

Abstract

A detailed numerical study on Ge and Si ultrathin-body (UTB) p-type double-gate MOSFET (pDG-FET) is carried out with the help of in-house developed non-equilibrium Green's function (NEGF) simulator employing the six-band k·p model. Six typical confinement/transport crystal orientation configurations and three recent technology nodes are taken into account for better evaluation of device performance. The ballistic velocity and effective mass (m eff ) are investigated and compared in detail between 3nm-thick Ge and Si films, with a better understanding of crystal orientation effect obtained. Device performance metrics, such as the ballistic ON-current (I ON ) and subthreshold swing (SS), are also extracted and compared. With the source-to-drain tunneling (SDT) effect characterized, further numerical analysis indicates that Ge device suffers from more terrible SDT than Si device at all the considered channel lengths. As the physics behind is clarified, some expectations and suggestions for improving device performance, especially for Ge case, are addressed in the end.