Nanotransfer-printed stamps allow fabrication of top-contact nanogap electrodes

Even though nanogap fabrication already has several well established methods for building electronic devices whose electrodes are merely few nanometers apart, options for depositing electrodes directly on top of nanoscale objects are still limited. New work using a new combined fabrication technique looks to provide a path forward for making small-spaced electrode pairs.

Saller et al. report results of using nanotransfer printing (nTP) with pre-patterned stamps that offer the opportunity to make new types of nanoelectronic device architectures. The stamps, made using molecular beam epitaxy with layered III-V semiconductors, were etched with a trench that served as the nanogap on printing. The technique produces stamps that allow for simultaneous integration of nanogap electrodes and contact pads for external electrical testing.

Major strengths of the approach include its ability to transfer nanoscale-patterned metal films and that it doesn’t require any post-processing, said author Marc Tornow.

“Future nanoscale electronic devices beyond today’s silicon technology may comprise various well-tailored, nanometer thin and sensitive conductive layers,” he said. “With our method, we offer a technology to make reliable electric contacts to these.”

The group’s stamps accommodate contact pads as long as 150 µm and electrode gaps as small as 30 nm. The authors state that the technique can be expected to yield features finer than 20 nm if edge roughness is minimized.

Tornow hopes the work benefits researchers who want to place top-contact thin sensitive films electrically in a one-step printing process without the need for post-processing. The authors are working to apply their methodology to contact thin, sensitive organic layers.

Source: “One-step transfer printing of patterned nanogap electrodes,” by Kai B. Saller, Hubert Riedl, Paolo Lugli, Gregor Koblmüller, and Marc Tornow, Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures (2019). The article can be accessed at https://doi.org/10.1116/1.5100560 .