Performance Evaluation and Optimization of Single Layer MoS2 Double Gate Transistors With Schottky Barrier Contacts

The making use of 2-D material as transistor channel is a rapid growth field since it can provide enough gate controllability for transistors at scaling limit. Among all kinds of 2-D materials, monolayer MoS2 stands out because of its large intrinsic bandgap and moderate mobility at room temperature. Most of the simulation work assumes the source/drain contacts of monolayer MoS2 transistors are Ohmic type, while in experiment the Schottky barrier contacts are more frequently seen. In this paper, the performance of single layer MoS2 double gate transistors with Schottky barrier contacts is evaluated with nonequilibrium Green's function method. The image force lowering effect, which is crucial for accurate simulation of Schottky barrier, is taken into account. The simulation results reveal that increasing doping concentration is the most effective way to adjust monolayer MoS2 transistor performance. Transistor performance with Schottky barrier contacts can be comparable and even outperforms those with Ohmic contacts. The dependence of subthreshold swing, drain-induced barrier lowering and intrinsic delay on Schottky barrier height, source/drain extension length, and doping concentration in source/drain extension region are also simulated and analyzed. The effect of phonon scattering on performance of monolayer MoS2 transistor with Schottky barrier contacts and Ohmic contacts is also presented.