Stability and reliability of carbon-coated solid-state nanopores for single molecule analysis

Solid-state nanopores has shown great potential for analyzing single molecules. Electron beaminduced carbon deposition enables precise tuning of nanopore dimension to adapt different molecule sizes. In this work, we investigate the stability of carbon-coated Si and SiN nanopores in a nanopore-gated nanocavity device, during electrical measurements in various solutions. Our results show that the conductance of bare nanopores increase over the measurement time, indicating pore expansion caused by electrochemical corrosion of the nanopore walls. Moreover, the corrosion accelerates with increasing voltages and electrolyte concentrations. In stark contrast, carbon-coated devices effectively resist electrochemical corrosion due to strong C=C bonds in the coating layer, exhibiting remarkable stability even in highly concentrated electrolytes and under strong electric fields. Furthermore, the carbon coating does not promote undesired surface interactions with analyte molecules during the translocation measurements. More importantly, we demonstrate that promptly releasing the electrical bias after trapping the molecule on a carbon-coated nanopore significantly reduces the risk of nonspecific adsorption onto the carbon-coated surface. Our results show that the stable, precisely size controlled, carbon-coated nanopores can play an important role for single molecule trapping and analysis.