h-BN-assisted Metal Contact Transfer to InSe for Two-Dimensional Multifunctional Electronic Devices

Metal contacts to two-dimensional (2D) semiconductors are crucial for determining the electrical performance of electronic devices. However, traditional three-dimensional metal deposition processes cause damage to 2D semiconductors and considerable Fermi-level-pinning effects. In this study, a hexagonal boron nitride (h-BN)-assisted transfer method was proposed for transferring metal contacts to few-layered InSe for fabricating 2D functional electronic devices. Using the transferred Pt electrodes as the contact, p-type dominated ambipolar conduction behavior with the hole Schottky barrier height (SBH) approaching 0 meV was observed in field-effect transistors (FETs) comprising multilayered InSe. Based on this phenomenon, several InSe homojunctions were fabricated using a dual-gate modulating method such as p-p, n-n, p-n, and n-p. For InSe p-n homojunctions, a current rectification ratio of over 10^4 and optoelectronic detection capabilities were achieved. Furthermore, a complementary metal-oxide-semiconductor (CMOS) inverter with an ultra-high voltage gain exceeding 60 at V_\rm DD=-1 V was fabricated. The proposed h-BN-assisted metal contact transfer method can be easily extended to other 2D semiconductors for fabricating complementary electronic and optoelectronic devices.