Electrochemical electrodes based on Laser Induced Graphene on PECVD a-SiC:H and Polyimide

The formation of graphene with defined patterns is crucial for the fabrication of graphene-based electrochemical devices as well as for different devices in microelectronics. In this work, we report an approach for producing and pattern continuous graphene trails by direct 405 nm laser writing at room temperature and atmospheric pressure on two different materials, hydrogenated amorphous silicon carbide films (a-SiC:H) produced by plasma enhanced chemical vapor deposition (PECVD), and polyimide, aiming their application in electrochemical sensors. The graphene lines produced on these substrates demonstrate high electrical conductivity and can be used directly with conductive contacts in different applications without the need of transferring to other insulating substrates, nor the removal of catalytic metals. Graphene trails of approximately
$7,5\ \text{mm}\times 30\mu\mathrm{m}$
were obtained on both materials by moving the substrate with the films in a computer controlled XY table and keeping fixed the laser source. Starting from a scanning speed of 300 and 500 mm/min, established in previous studies, variations were made between the laser-substrate distance, the thickness of the a-SiC:H film and the position of the sample, identifying a great dependence of the graphene quality on these parameters. The obtained graphene trails were characterized by raman spectroscopy and scanning electron microscopy, showing continuity in the trails. Electrical measurements through Au/Ti (200nm/20nm) electrodes showed high conductivity with sheet resistances (Rs) ranging from
$897\Omega$
to
$2\ \mathrm{k} \Omega$
per square in the Silicon carbide samples and
$39,7\Omega$
on the polyamide ones. Also electrochemical electrodes were fabricated and the first cyclic voltammetry measurements showed very promising results. Being fast, efficient and low-cost this technique opens up great new possibilities for manufacturing both, sensors and microelectronic devices.