Ambipolar Transport Based on CVD-synthesized ReSe₂

Rhenium diselenide (ReSe₂) is a member of 2D semiconducting materials with in-plane anisotropic electrical and optical properties. We report the electrical behaviors of ReSe₂ synthesized via a chemical vapor deposition (CVD) method. Differently from previous reports on unipolar ReSe₂ FETs, the synthesized-ReSe₂ FETs have ambipolar characteristics when it contacts with gold electrode. This device shows high on/off current ratios over 10⁴ for both of hole and electron. Moreover, there was little dependence of the behavior on the thickness. However, depending on the electrode metal, the main charge carrier type was changed. We measured the work function for synthesized ReSe₂ in order to investigate the ambipolar characteristic using Kelvin probe force microscopy (KPFM). We also designed an inverter to study the feasibility of its application in logic circuits. Additionally, the atomic structure of the synthesized ReSe₂, which has triclinic crystal system, was confirmed by transmission electron microscope (TEM), and the corresponding vibration modes were checked by Raman spectroscopy.