Two-dimensional-materials-based transistors using hexagonal boron nitride dielectrics and metal gate electrodes with high cohesive energy

Abstract

Two-dimensional (2D) semiconductors could potentially be used as channel materials in commercial field-effect transistors. However, the interface between 2D semiconductors and most gate dielectrics contains traps that degrade performance. Layered hexagonal boron nitride (h-BN) can form a defect-free interface with 2D semiconductors, but when prepared by industry-compatible methods—such as chemical vapour deposition (CVD)—the presence of native defects increases leakage current and reduces dielectric strength. Here we show that metal gate electrodes with a high cohesive energy—platinum and tungsten—can allow CVD-grown layered h-BN to be used as a gate dielectric in transistors. The electrodes can reduce the current across CVD-grown h-BN by a factor of around 500 compared to similar devices with gold electrodes and can provide a high dielectric strength of at least 25 MV cm−1. We examine the behaviour statistically across 867 devices, which includes a microchip based on complementary metal–oxide–semiconductor technology. Metal gate electrodes with a high cohesive energy—platinum and tungsten—can be used to mitigate leakage currents and premature dielectric breakdown across chemical vapour deposition-grown multilayer hexagonal boron nitride, allowing the material to be used as a gate dielectric in two-dimensional-materials-based transistors.