New concept of planar germanium MOSFET with stacked germanide layers at source/drain

Abstract

In this paper, we have proposed and simulated one novel Schottky barrier germanium-based MOSFET structure. Herein, the source/drain region of the device is consisted with two stacked layers of germanide materials. Different barrier heights of the top and bottom contact are hence formed with channel respectively. The top barrier height is designed lower enough to enlarge drive current, and the bottom barrier height is higher (nearly mid-gap) to diminish the leakage current. The working mechanism and the performance of n- and p-type devices is studied. Comparisons between dual barrier structure and single barrier structure are also carried out. The results show that the characteristics have been significantly enhanced with the proposed dual barrier structure. Besides, the devices’ performance is nearly insensitive to germanium thickness, which leads to the relax of the requirement of germanium-on-insulator (GeOI) structures for leakage immunization.