We report the successful application of a new approach, ice lithography (IL), to fabricate nanoscale devices. The entire IL process takes place inside a modified scanning electron microscope (SEM), where a vapor-deposited film of water ice serves as a resist for e-beam lithography, greatly simplifying and streamlining device fabrication. We show that labile nanostructures such as carbon nanotubes can be safely imaged in an SEM when coated in ice. The ice film is patterned at high e-beam intensity and serves as a mask for lift-off without the device degradation and contamination associated with e-beam imaging and polymer resist residues. We demonstrate the IL preparation of carbon nanotubes field effect transistors (FETs) with high quality trans-conductance properties.

We demonstrate that voltage-biased solid-state nanopores can transiently localize DNA in an electrolyte solution. A double-stranded DNA (dsDNA) molecule is trapped when the electric field near the nanopore attracts and immobilizes a non-end segment of the molecule across the nanopore orifice without inducing a folded molecule translocation. In this demonstration of the phenomenon, the ionic current through the nanopore decreases when the dsDNA molecule is trapped by the nanopore. By contrast, a translocating dsDNA molecule under the same conditions causes an ionic current increase. We also present finite-element modeling results that predict this behavior for the conditions of the experiment.

A fabrication method for positioning and embedding a single-walled carbon nanotube (SWNT) across the diameter of a solid state nanopore is presented. Chemical vapor deposition (CVD) is used to grow SWNTs over arrays of focused ion beam (FIB) milled pores in a thin silicon nitride membrane. This typically yields at least one pore whose diameter is centrally crossed by a SWNT. The final diameter of the FIB pore is adjusted to create a nanopore of any desired diameter by atomic layer deposition (ALD), simultaneously embedding and insulating the SWNT everywhere but in the region that crosses the diameter of the final nanopore, where it remains pristine and bare. This nanotube-articulated nanopore is an important step towards the realization of a new type of detector for biomolecule sensing and electronic characterization, including DNA sequencing.2

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