Atomic Layer Deposition to Fine-Tune the Surface Properties and Diameters of Fabricated Nanopores

We found that under our conditions the deposition rate of Al2O3 was 0.099 per reaction cycle, independent of the total number of cycles

Peng Chen; Toshiyuki Mitsui; Damon B. Farmer; Jene Golovchenko; Roy G. Gordon; Daniel Branton


Scholarcy highlights

  • Nanopore sensors, whose ionic conductivity can be diminished by the passage of target molecules, can transduce the passage of a single macromolecule into a discrete electrical signal whose characteristics reveal some of the translocating molecule’s properties. But despite the stability, tunability, and other potential advantages that fabricated solid state nanopores may offer, the ion beam, electron beam, or chemical etch fabrication conditions used to create nanopores usually yield uncharacterized and possibly unfavorable surface properties that can interfere with the pore’s sensing abilities
  • As anticipated given the lack of ion selectivity, high throughput DNA translocation was observed in all of our ALD-Al2O3 pores and, in addition, 1/f noise was gratifyingly insignificant at all voltage levels, ensuring sufficient signal-to-noise ratio for detecting DNA translocation
  • In 14 independent trials on plain FIB-drilled nanopores and 17 trials on ion beam sculpted nanopores, we found that all of the pores had been closed down to their predicted size while still maintaining their initial shapes
  • Our results demonstrate a strategy of using atomic layer deposition to improve or create a single-molecule sensor by precisely adjusting a pore’s diameter while simultaneously modifying the product’s critical surface properties in a well controlled manner
  • Starting with an already small ion beam sculpted nanopore of known diameter in a thin membrane, a short, molecularly sized nanopore can be fashioned with atomic precision without the need for final TEM verification
  • This large pore was subsequently sculpted with feedback control using a 3-keV Ar+ ion beam, during which process the pore size was continuously monitored by counting the Ar+ flux through the pore
  • The Ar+ ion beam stimulated lateral atomic flow of Si3N4 to create a thin film of Si3N4 material that defines a nanopore at one end of the cylindrical FIB pore

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