Ambipolar transport based on CVD-synthesized ReSe ₂

Abstract Control of the carrier type in two dimensional (2D) materials is a serious issue for the realization of logic devices. The carrier type control of 2D semiconducting materials such as MoTe ₂ , WSe ₂ and black phosphorus have been studied for this purpose. However, the systematic study on the polarity control of transistors based on ReSe ₂ , a new member of 2D materials, has remained unexplored despite the intriguing anisotropic optical and electrical properties deriving from the exotic crystal structure. Here, we report the electrical characterization of field effect transistors (FETs) of single crystalline ReSe ₂ grown by a chemical vapor deposition. In contrast to a previous report of unipolar p-type exfoliated crystals, synthesized ReSe ₂ FETs on SiO ₂ with Au contact exhibit highly symmetric ambipolar behaviors with the current on/off ratios of ~10 ⁴ for both of hole and electron injection. The carrier type could be controlled via the metal contact. With Al contacts, ReSe ₂ FETs display perfect transition to pure n-type unipolar behavior. It is found that carrier type of ReSe ₂ via thickness variation was hardly modulated because the ReSe ₂ bandgap has little dependence on its thickness. We successfully achieved the fabrication of a logic inverter by using only ambipolar ReSe ₂ FETs on SiO ₂ /Si without electrostatic doping or chemical treatments. These results demonstrate that ReSe ₂ is a promising candidate for future low power logic devices and functional nano electronic applications.