Fabrication and Characterization of Micrometer Scale Graphene Structures for Large-Scale Ultra-Thin Electronics

Abstract

Graphene offers many useful properties that can revolutionize modern electronic devices. Specifically, it provides high charge carrier mobility in a mechanically robust, atomically thin form factor. Many of these properties are observed in graphene which is prepared from exfoliated graphite and processed with electron beam lithography. These processes are both time intensive and cost- prohibitive for the large-scale production necessary for use in consumer electronics. This work details the processing and characterization of commercially available graphene from chemical vapor deposition (CVD) on SiO2/Si and on hBN-layered SiO2/Si wafers using conventional photolithography on the 4″ wafer standard. The findings indicate that the CVD graphene films are resilient after processing even for lengths up to 1 mm. Electrical characterization via resistance measurements and the Hall Effect at room temperature clearly indicates the influence of the substrate material on the graphene’s electrical properties. At these length scales, graphene on SiO2 resembles that of a lightly doped semiconductor in terms of its carrier density (7.8 × 1015 cm−2), yet its carrier mobility (2.6 cm2/Vs) resembles that of a metal. Graphene on hBN/SiO2 has a carrier density of 8.2 × 1012 cm−2 and carrier mobility of 2.68 × 103 cm2/Vs—comparable to existing high-mobility semiconducting materials. CVD graphene and conventional photolithography does provide a cost-effective means for producing large form-factor graphene devices for low to moderate mobility applications and eventually for large-scale monolithic graphene electronics.

Experimental demonstration of cyclotron emissions in micro-scale graphene structures

“…The wafer with the graphene arcs exhibited total resistance of 7.75 kΩ whereas the reference wafer showed open circuit readings thus verifying that the graphene structures were indeed removed. The methods and procedures are detailed in Planillo et al 36 .…”

“…The graphene semicircular arc geometries for this experiment were designed with a 10 µm radius and 10 µm width as this geometry can be readily fabricated with conventional photolithography methods. Initial characterization of commercially obtained graphene on hBN/SiO 2 /Si substrates 35 shows that the measured saturation velocity is 1.87 × 10 7 cm/s 28 , 29 , 36 , 37 . With this saturation velocity, the arcs are expected to emit at a target frequency of 2.9 GHz at a power of 3.96 nW as given by Eqs.…”