Intriguing field-effect-transistor performance of two-dimensional layered and crystalline CrI₃

There are many candidate materials that can be used as channel materials for the next-generation field effect transistors (FETs). CrI₃ is one of the particular candidates for application in FET, because it is a two-dimensional (2D) ferromagnet and has giant tunneling magnetoresistance. The ferromagnetic nature extends to not only electronics but also spintronics. In this study, the large-area, layered, and crystalline 2D CrI₃ were synthesized by horizontal Bridgman method. The suspended CrI₃ FETs were fabricated for explorations of intrinsic electron transport in the CrI₃ channel and of electrical contact problems. The suspended FET structure lets the CrI₃ channel free from trapping charges in the SiO₂-capped Si substrate. The on–off ratio of the suspended CrI₃ FET is up to 10⁴, making the 2D layered CrI₃ potential for future FETs. The investigations of the mobility and the interface-trap density at various temperatures reveal that the trapping charges as well as the interface-trap densities are increased with further gas adsorption on the surface of the CrI₃ flake. The performance of the suspended CrI₃ FET can be improved, if the gas adsorption problem can be carefully treated.