Materials with honeycomb structures for gate dielectrics in two-dimensional Field Effect Transistors - An ab initio study

The size of the Field Effect Transistor (FET) has been decreasing exponentially each year to keep up with the demands of the microelectronic industry. However, this scaling is now reaching its limits due to the performance of the materials currently used in the FET. Specifically, the leakage through silicon dioxide, the current gate dielectric, is beginning to inhibit the FET's performance. Recently, attention has been turning towards two-dimensional materials for electronic devices. However, insulating is especially challenging for two-dimensional materials due to the short diffusion length for charge carriers. We consider several materials that have been shown to have a stable two-dimensional honeycomb structure. In order to characterize these materials, we use Density Functional Theory (DFT) to calculate key properties that determine performance, including the dielectric function, band gap, and effective mass. We check the compatibility of these materials with Molybdenum Disulfide (MoS2), a two-dimensional material that has emerged as a promising candidate for the semiconducting channel of a FET. We have identified several promising candidates, including hBN, which is the common choice as a dielectric material, and LiF and BeO, which are materials that have not been used before as gate dielectrics. We anticipate that this study will contribute to advancing the development of transistors that are made completely of two-dimensional materials.