Improving the neutrality point uniformity for SG-FET-based DNA sensor

Graphene grown on copper foils by chemical vapor deposition can be directly deposited or transferred to the desired substrates. When a CVD-grown graphene sheet is transferred, its surface may be affected by the handling process and environmental conditions. Defects and contamination on the graphene surface induce unstable electrical characteristics, like in the neutrality point, also known as Dirac point. For this reason, it is hard to quantitatively analyze the results due to an inconstant Dirac point. To overcome this fabrication problem, this study proposes a method to reduce the defects and preserve the initial characteristics of the material, minimizing the damage during the graphene transfer. A high-quality graphene sheet was transferred onto several pairs of electrodes to maintain the original electrical properties. In the device structure proposed herein, the error range of the Dirac point was less than +/- 1 mV. We confirmed the transfer characteristics of our device by detecting the hybridization of complementary DNAs to probe DNAs immobilized on the graphene active layer. Also, this new structure can be used to analyze biological samples using different bioreceptors in each channel. Maintaining the detection region may guarantee the stability of graphene properties as an active layer.