Improvement of electrical performance using PtSe2/PtTe2 edge contact synthesized by molecular beam epitaxy.

A PtSe2-based edge-contact field-effect transistor (FET) incorporating PtSe2 as the channel material and PtTe2 as the contact metal is fabricated using tellurization on only a selected region. The higher on–off ratio of the PtSe2-based edge-contact device compared to other synthesized PtSe2-based FETs is successfully achieved by reducing the contact resistance. [Display omitted] One-dimensional (1D) edge contact is considered critical to reducing contact resistance between two-dimensional transition-metal dichalcogenides (TMDs) and contact metal and overcoming surface contact effects, such as surface damage and orbital hybridization. Although several studies have investigated edge contact, some problems such as inevitable etching damage and a limited area persist. Herein, a tellurization method is applied to a specific lateral region to fabricate PtTe 2 /PtSe 2 /PtTe 2 edge-contact field-effect transistors (FETs) without etching damage. High-resolution X-ray photoelectron spectroscopy and Raman spectroscopy are used to verify tellurization completion, which is evidenced by the complete transformation of PtSe 2 to PtTe 2 by the substitution of Se atoms with evaporated Te atoms. Furthermore, tellurization is applied to a specific lateral region by utilizing the hexagonal boron nitride to block the interdiffusion of evaporated Te atoms, which is confirmed by Raman spectroscopy and cross-sectional annular dark-field scanning transmission electron microscopy. Finally, the 1D edge-contact FETs fabricated by tellurization demonstrate a higher on–off ratio and carrier mobility than the surface-contact FET. Therefore, this method can be applied to various FETs based on TMDs for improving electrical performance through a reduction in contact resistance. [ABSTRACT FROM AUTHOR]