Demonstration of electronic devices in graphitic carbon nitride crystalline film

Graphitic carbon nitride (g-C3N4) exhibits semiconducting properties and is a promising candidate for use as a metal-free functional material. Electronic transport in g-C3N4 depends on the crystal orientation, resulting in the anisotropic characteristics of low out-of-plane and high in-plane resistivity. We investigated a Schottky barrier diode (SBD) and a heterojunction diode (HJD) with out-of-plane transport properties and a top-gate device with in-plane transport properties. The SBD with a Cr/Au Schottky contact exhibited rectifying behavior with a turn-on voltage of ∼1.0 V and estimated series resistance and barrier height at the interface of 1.63 kΩ and 344 meV, respectively. The HJD comprises a g-C3N4 film and an n-type hexagonal silicon carbide (4H–SiC) substrate, with a turn-on voltage of 4.0 eV. The HJD belonged to a type-II band alignment with a staggered-gap; it had a thin insulator-based van der Waals gap at the interface, thereby inducing tunneling transport. In-plane carrier transport control was carried out by the top-gate device with a Parylene-C film gate dielectric and was achieved only when the negative bias voltage was applied along the out-of-plane direction, indicating the realization of the normally off switch that utilizes the intrinsic transport characteristics and a simple device structure.