Tungsten Diselenide Top-gate Transistors with Multilayer Antimonene Electrodes: Gate Stacks and Epitaxially Grown 2D Material Heterostructures.

We have demonstrated that with e-beam deposition of a thin Al2O3 layer before atomic layer deposition, a uniform Al2O3 film can be obtained on WSe2/sapphire samples. Device performances are observed for WSe2 top-gate transistors by using oxide stacks as the gate dielectric. By using thermal evaporation, epitaxially grown multilayer antimonene can be prepared on both MoS2 and WSe2 surfaces. With multilayer antimonene as the contact metal, a significant increase in drain currents and ON/OFF ratios is observed for the device, which indicates that high contact resistance between metal/2D material interfaces is a critical issue for 2D devices. The observation of multilayer antimonene grown on different 2D material surfaces has demonstrated less dependence on the substrate lattice constant of the unique van der Waals epitaxy for 2D materials. The results have also demonstrated that stacking 2D materials with different materials plays an important role in the practical applications of 2D devices.