Monolithic Integration of Vertical Thin-Film Transistors in Nanopores for Charge Sensing of Single Biomolecules

We propose and fabricate solid-state nanopore devices that monolithically integrate solution-gated, vertical thin-film transistors (TFTs) inside the nanopores for charge-based sensing of translocating biomolecules. The TFTs consist of zinc oxide semiconductor channels and aluminum oxide gate dielectrics, which are both conformally deposited along the inner surfaces of the nanopores via atomic layer deposition. The resultant TFT channel lengths and nanopore diameters both reach the ∼10 nm range. In translocation experiments using λ-DNAs or bovine serum antibody (BSA) proteins, the TFT-nanopore devices demonstrate concurrent detection of the ion conductance blockade signals and modulation signals in the TFT electrical current. The TFT signals show opposite signs for the negatively charged DNAs and positively charged BSAs as well as staircase signal shapes that correspond to the folding and knotting of λ-DNAs. Further experiments under various electrical biases and solution ionic strengths show that the ion blockade signals and the TFT signals have different dependence upon these experimental conditions. The TFT signals are analyzed to be consistent with the field effect sensing of the biomolecular charge, and the induced mirror charge is estimated from the signal amplitudes. This study could be a step forward to achieve charge-based single-biomolecular technology for basic research as well as for biosensing applications. It may also stimulate the development of TFT technologies for conformal integration of semiconductor electronics at the front end of nanostructures.