title: The use of etched registration markers to make four-terminal electrical contacts to STM-patterned nanostructures.
abstract: We demonstrate the use of etched registration markers for the alignment of four-terminal ex situ macroscopic contacts created by conventional optical lithography to buried nanoscale Si:P devices, patterned by hydrogen-based scanning tunnelling microscope (STM) lithography. Using SiO(2) as a mask we are able to protect the silicon surface from contamination during marker fabrication and can achieve atomically flat surfaces with atomic-resolution imaging. The registration markers are shown to withstand substrate heating to approximately 1200 degrees C and epitaxial overgrowth of approximately 25 nm Si. Using a scanning electron microscope to position the STM tip with respect to the markers, we can achieve alignment accuracies of approximately 100 nm, which allows us to contact buried Si:P structures. We have applied this technique to fabricate P-doped wires of different widths and measured their I-V characteristics at 4 K, finding ohmic behaviour down to a width of approximately 27 nm.
authors.affiliation: Australian Research Council Centre of Excellence for Quantum Computer Technology, University of New South Wales, Sydney, NSW 2052, Australia. School of Physics, University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: F J
authors.initials: FJ
authors.lastname: Rueß
authors.forename: L
authors.initials: L
authors.lastname: Oberbeck
authors.forename: K E J
authors.initials: KE
authors.lastname: Goh
authors.forename: M J
authors.initials: MJ
authors.lastname: Butcher
authors.forename: E
authors.initials: E
authors.lastname: Gauja
authors.forename: A R
authors.initials: AR
authors.lastname: Hamilton
authors.forename: M Y
authors.initials: MY
authors.lastname: Simmons