Optimizing 2D-metal contact in layered Tin-selenide via native oxide modulation

The discovery of two-dimensional(2D)semiconductor has opened up new avenues for the development of short-channel field-effect transistors(FETs)with desired electrical performance.Among them,orthorhombic tin-selenide(SnSe)has garnered increasing attention due to its potential applications in a variety of electronic,optoelectronic,and thermoelectric devices.However,the realization of high-performance SnSe FETs with low contact resistance(Rc)remains a challenge.Herein,we systematically investigate the contact of few-layer SnSe FETs through the modulation of native oxide on SnSe by using different metals.It is found that chromium(Cr)-contacted devices possess the best FET performance,such as electron mobility up to 606 cm^(2)/(V·s)at 78 K,current on/off ratio exceeding 1010,and saturation current of~550μA/μm,where a negligible Schottky barrier(SB)of~30 meV and a low contact resistance of~425Ωμm are achieved.X-ray photoelectron spectroscopy(XPS)and cross-sectional electron dispersive X-ray spectroscopy(EDX)results further reveal that the improved contact arises from the Cr-induced reduction of native oxide(SnOx)to Sn,which thins the tunneling barrier for efficient electron injection.Our findings provide a deep insight into the 2D-metal contact of SnSe and pave the way for its applications in future nanoelectronics.