Performance improvement of multilayer InSe transistors with optimized metal contacts

This work is focused on achieving high performance multilayer InSe field-effect transistors by a systematic experiment study on metal contacts. The high performance can be achieved by choosing an ideal contact metal and adopting a proper thickness of InSe nanosheets. By choosing a proper thickness (33 nm), the performance of multilayer InSe FETs was improved by the following sequence of Al, Ti, Cr and In contacts. The extracted mobility values are 4.7 cm² V^-1 s^-1, 27.6 cm² V^-1 s^-1, 74 cm² V^-1 s^-1 and 162 cm² V^-1 s^-1 for Al, Ti, Cr and In, respectively. The on/off ratios are 10⁷-10⁸. The device electronic properties and the interface morphology of the deposition metals/InSe indicate that the contact interface between the metals and InSe plays a significant role in forming low resistance. Our study may pave the way for multilayer InSe applications in nano-electrical and nano-optoelectronic devices.