Planar nanogap electrodes by direct nanotransfer printing

The fabrication of planar nanogap electrodes on a silicon substrate, using direct high-resolution metal nanotransfer printing (nTP) was investigated. Molecular beam epitaxy (MBE) molds were obtained by growing a single-crystalline AlGaAs layer of micrometer thickness on top of a GaAs substrate wafer, followed by either a single, thick GaAs layer or by a sequence of alternating GaAs and AlGaAs layers, followed by a second, micrometer-thick AlGaAs layer. All these mentioned layers were separated by 100-nm-wide support structures of the opposite material. Single-line molds were fabricated from a heterostructure comprising two 2-p.m-thick AlGaAs planes on either side of a buried 10-nm-thick GaAs layer. Subsequent to selective etching, the samples were flushed with deionized water and blown dry with nitrogen. Electrical shorts were experienced despite the SEM inspection, indicating the presence of a gap.