The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Default user image.

Martin Magnusson

deputy head of department

Default user image.

Optical far-field extinction of a single GaAs nanowire towards in situ size control of aerotaxy nanowire growth

Author

  • Yang Chen
  • Nicklas Anttu
  • Sudhakar Sivakumar
  • Eleni Gompou
  • Martin H. Magnusson

Summary, in English

A substrate-free approach of semiconductor nanowire growth has been achieved by the aerotaxy technique previously. In this work, we propose an in situ method to monitor the size of nanowires through non-destructive optical-extinction measurements. Our work aims to build a theoretical look-up database of extinction spectra for a single nanowire of varying dimensions. We describe the origin of possible peaks in the spectra, for example due to nanowire-length dependent Fabry-Perot resonances and nanowire-diameter dependent TM and TE mode resonances. Furthermore, we show that the Au catalyst on top of the nanowire can be ignored in the simulations when the volume of the nanowire is an order of magnitude larger than that of the Au catalyst and the diameter is small compared to the incident wavelength. For the calculation of the extinction spectra, we use the finite element method, the discrete dipole approximation and the Mie theory. To compare with experimental measurements of randomly oriented nanowires, we perform an averaging over nanowire orientation for the modeled results. However, in the experiments, nanowires are accumulating on the quartz window of the measurement setup, which leads to increasing uncertainty in the comparison with the experimental extinction spectra. This uncertainty can be eliminated by considering both a sparse and a dense collection of nanowires on the quartz window in the optical simulations. Finally, we create a database of extinction spectra for a GaAs nanowire of varying diameters and lengths. This database can be used to estimate the diameter and the length of the nanowires by comparing the position of a peak and the peak-to-shoulder difference in the extinction spectrum. Possible tapering of nanowires can be monitored through the appearance of an additional peak at a wavelength of 700-800 nm.

Department/s

  • Solid State Physics
  • NanoLund: Centre for Nanoscience

Publishing year

2020-01-09

Language

English

Publication/Series

Nanotechnology

Volume

31

Issue

13

Document type

Journal article

Publisher

IOP Publishing

Topic

  • Condensed Matter Physics
  • Nano Technology

Keywords

  • semiconductor nanowire
  • light scattering
  • aerotaxy growth

Status

Published

ISBN/ISSN/Other

  • ISSN: 0957-4484