Simulation of thin-TFETs using transition metal dichalcogenides: effect of material parameters,gate dielectric on electrostatic device performance

In recent years, significant of scientific research effort has focused on the investigation of transition metal dichalcogenides (TMDC) and other two-dimensional (2D) materials like graphene or boron nitride. Theoretical investigation on the physical aspects of these materials has revealed a whole new range of exciting applications due to wide tunability in electronic and optoelectronic properties. Besides theoretical exploration, these materials have been successfully implemented in electronic and optoelectronic devices with promising results. In this work, we have investigated the effect of monolayer TMDC materials and monolayer TMDC alloys on the performance of thin tunneling field-effect transistors or thin-TFETs. These are promising electronic devices that can achieve steep switching characteristics. We have used the self-consistent determination of the conduction and valence band levels in the device and a simplified model of interlayer tunneling current reported in recent literature that treats scattering semiclassically and incorporates the energy broadening effect using a Gaussian approximation . We have also explored the effect of gate dielectric material variation, interlayer dielectric variation, top gate metal workfunction on the performance of the device. Our study shows that proper choice of material in the top and bottom layers, optimization of materials used as gate and interlayer dielectric are necessary to extract the full potential of these devices. The electron affinity and bandgap of the TMDCs used in different layers effectively control the threshold voltage and current in the device. As seen from our simulation, interlayer materials with high dielectric constant can degrade subthreshold device performance, increase threshold voltage, whereas lowering interlayer thickness could increase device ‘on’ current at the expense of degraded subthreshold performance.