Home > Press > Researchers Peer Into Nanowires to Measure Dopant Properties
Abstract:
Semiconductor nanowires -- tiny wires with a diameter as small as a few billionths of a meter -- hold promise for devices of the future, both in technology like light-emitting diodes and in new versions of transistors and circuits for the next generation of electronics. But in order to utilize the novel properties of nanowires, their composition must be precisely controlled, and researchers must better understand just exactly how the composition is determined by the synthesis conditions.
Nanowires are synthesized from elements that form bulk semiconductors, whose electrical properties are in turn controlled by adding minute amounts of impurities called dopants. The amount of dopant determines the conductivity of the nanowire.
But because nanowires are so small -- with diameters ranging from 3 to 100 nanometers -- researchers have never been able to see just exactly how much of the dopant gets into the nanowire during synthesis. Now, using a technique called atom probe tomography, Lincoln Lauhon, assistant professor of materials science and engineering at Northwestern University's McCormick School of Engineering and Applied Science, has provided an atomic-level view of the composition of a nanowire. By precisely measuring the amount of dopant in a nanowire, researchers can finally understand the synthesis process on a quantitative level and better predict the electronic properties of nanowire devices.
The results were published online March 29 in the journal Nature Nanotechnology.
"We simply mapped where all the atoms were in a single nanowire, and from the map we determined where the dopant atoms were," said Lauhon. "The more dopant atoms you have, the higher the conductivity."
Previously, researchers could not measure the amount of dopant and had to judge the success of the synthesis based on indirect measurements of the conductivity of nanowire devices. That meant that variations in device performance were not readily explained.
"If we can understand the origin of the electrical properties of nanowires, and if we can rationally control the conductivity, then we can specify how a nanowire will perform in any type of device," said Lauhon. "This fundamental scientific understanding establishes a basis for engineering."
He and his group performed the research at Northwestern's Center for Atom Probe Tomography, which uses a Local Electrode Atom Probe microscope to dissect single nanowires and identify their constituents. This instrumentation software allows 3-D images of the nanowire to be generated, so Lauhon could see from all angles just how the dopant atoms were distributed within the nanowire.
In addition to measuring the dopant in the nanowire, Lauhon's colleague, Peter Voorhees, Frank C. Engelhart Professor of Materials Science and Engineering at Northwestern, created a model that relates the nanowire doping level to the conditions during the nanowire synthesis. The researchers performed the experiment using germanium wires and phosphorous dopants -- and they will soon publish results using silicon -- but the model provides guidance for nanowires made from other elements, as well.
"This model uses insight from Lincoln's experiment to show what might happen in other systems," Voorhees says. "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."
Both professors will continue working on this research to broaden the model.
"We would like to establish the general principles for doping semiconductor nanowires," said Lauhon.
The paper is titled "Direct Measurement of Dopant Distribution in an Individual Vapour-liquid-solid Nanowire." In addition to Lauhon and Voorhees, the other authors are Daniel E. Perea, Eric R. Hemesath, Edwin J. Schwalbach and Jessica L. Lensch-Falk, all from Northwestern.
The Office of Naval Research and the National Science Foundation supported the research.
####
About Northwestern University
Research thrives at Northwestern University, with an annual budget of over $1.5 billion and more than $439 million in sponsored research. At Northwestern, and often with partners at Argonne National Laboratory, Fermilab, and local universities, interdisciplinary teams work to solve society's problems and facilitate clinical and commercial use of their innovations.
For more information, please click here
Contacts:
Megan Fellman
(847) 491-3115
Copyright © Northwestern University
If you have a comment, please Contact us.Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
Related Links |
Northwestern’s Center for Atom Probe Tomography
Related News Press |
News and information
New method in the fight against forever chemicals September 13th, 2024
Energy transmission in quantum field theory requires information September 13th, 2024
Breakthrough in proton barrier films using pore-free graphene oxide: Kumamoto University researchers achieve new milestone in advanced coating technologies September 13th, 2024
Quantum researchers cause controlled ‘wobble’ in the nucleus of a single atom September 13th, 2024
Possible Futures
Rice research could make weird AI images a thing of the past: New diffusion model approach solves the aspect ratio problem September 13th, 2024
New discovery aims to improve the design of microelectronic devices September 13th, 2024
Nanoelectronics
Interdisciplinary: Rice team tackles the future of semiconductors Multiferroics could be the key to ultralow-energy computing October 6th, 2023
Key element for a scalable quantum computer: Physicists from Forschungszentrum Jülich and RWTH Aachen University demonstrate electron transport on a quantum chip September 23rd, 2022
Reduced power consumption in semiconductor devices September 23rd, 2022
Atomic level deposition to extend Moore’s law and beyond July 15th, 2022
Announcements
New discovery aims to improve the design of microelectronic devices September 13th, 2024
New method in the fight against forever chemicals September 13th, 2024
The latest news from around the world, FREE | ||
Premium Products | ||
Only the news you want to read!
Learn More |
||
Full-service, expert consulting
Learn More |
||