According to a paper published in a recent issue of Nature Nanotechnology, two researchers at Northwestern University are using atom probe tomography to do precise atom-by-atom measurements of dopants in nanowires and, likewise, use the information to build new nanowire models and better predict their electronic properties.

Lincoln Lauhon, assistant professor of materials science and engineering at the school’s McCormick School of Engineering and Applied Science, is providing the atomic-level view of the composition of nanowire.

Lauhon did his working using a Local Electrode Atom Probe microscope, obtaining a 3-D map of individual atoms within the wire. “We simply mapped where all the atoms were in a single nanowire, and from the map we determined where the dopant atoms were,” he says. Quantitative dopant information is key to nanowire development because conductivity increases with an increase in dopant atoms.

Lauhon predicted this ability would unleash new engineering possibilities. Indeed, one of Lauhon’s colleague, Peter Voorhees, is already using this mapping ability to develop new approaches to synthesizing germanium nanowires with phosphorous dopants.

“If nanowires are going to be used in device applications, this model will provide guidance as to the conditions that will enable us to add these elements and control the doping concentrations,” Vorhees says.

Lauhon predicts that they will be able to establish basic principles and guidelines for doping nanowires.