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 cm(2) V(-1) s(-1), 27.6 cm(2) V(-1) s(-1), 74 cm(2) V(-1) s(-1) and 162 cm(2) V(-1) s(-1) for Al, Ti, Cr and In, respectively. The on/off ratios are 10(7)-10(8). 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.