The electrical resistance of laser-induced graphene synthesized by a continuous-wave CO$_2$-laser

Laser-Induced Graphene (LIG) is a promising new material for widespread applications in electronics and medicine. This study presents experimental results on measuring its specific conductivity $(\sigma)$, sheet resistance $(R_s)$, as well as contact resistance $(R_c)$ and specific contact resistance $(\rho_c)$ of a copper electrode with the LIG film structure synthesized on the surface of a polyimide film using the method of its near-surface layer pyrolysis through line-by-line scanning of a focused beam of $cw$ carbon dioxide laser. It is established that the synthesized LIG film structure exhibits anisotropy in electrical resistance, attributed to the line-by-line scanning. It is demonstrated that $\sigma$, $R_s$, $R_c$, and $\rho_c$ significantly depend on the fluence $(F)$ of the incident laser radiation. Measured values of $\sigma$, $R_s$, $R_c$, and $\rho_c$ varied in the ranges of 7.7 $\div$ 10 S/cm, 26 $\div$ 49 $\Omega/sq$, and 9 $\div$ 43 $\Omega$ $\cdot$ mm$^2$, respectively, with an increase in $F$ from 31 to 137 J/cm$^2$.