Enhanced electrical properties of hybrid monolayer graphene and insulating flat Si₃N₄ with bottom-up stenciled electrodes

Graphene, a two-dimensional material of carbon atoms in a honeycomb lattice, with many extraordinary properties is used to make nano and microelectronic devices. In this study, electrical properties of extensive monolayer graphene area (1.6 × 10^–2 m²) produced by chemical vapor deposition was investigated. Electrical contacts were formed by bottom-up patterning of Cr on Si₃N₄ insulating substrates using a wire cut stencil mask in a physical vapor deposition setup. The graphene sheet was then transferred over the electrical contacts. Surface characterization with AFM, Raman spectroscopy, TEM and electron diffraction have been effective in identifying the defects, holes, wrinkles, and the number of layers. Current–voltage and resistance characterizations were performed with an I–V measurement setup and a four-point probe system. The results show that monolayer graphene with linear/ohmic behavior is well insulated from the flat substrate regardless of the holes, wrinkles and impurities induced due to the wet transfer. The currents achieved here with Si₃N₄ and stencil mask, are one to two orders of magnitude larger than those obtained with SiO₂ and lithographic methods presented in the literature. These signify that exploiting flatter substrates and cleaner electrode deposition methods clearly enhances electrical properties of graphene-based devices.