Nano Research

, Volume 5, Issue 12, pp 863–874

Drastically increased absorption in vertical semiconductor nanowire arrays: A non-absorbing dielectric shell makes the difference

  • Nicklas Anttu
  • Kousar L. Namazi
  • Phillip M. Wu
  • Pengfei Yang
  • Hongxing Xu
  • H. Q. Xu
  • Ulf Håkanson
Research Article

DOI: 10.1007/s12274-012-0270-x

Cite this article as:
Anttu, N., Namazi, K.L., Wu, P.M. et al. Nano Res. (2012) 5: 863. doi:10.1007/s12274-012-0270-x

Abstract

Enhanced absorption of especially long wavelength light is needed to enable the full potential of semiconductor nanowire (NW) arrays for optoelectronic applications. We show both experimentally and theoretically that a transparent dielectric shell (Al2O3 coating) can drastically improve the absorption of light in InAs NW arrays. With an appropriate thickness of the Al2O3 shell, we achieve four times stronger absorption in the NWs compared to uncoated NWs and twice as good absorption as when the dielectric completely fills the space between the NWs. We provide detailed theoretical analysis from a combination of full electrodynamic modeling and intuitive electrostatic approximations. This reveals how the incident light penetrates better into the absorbing NW core with increasing thickness of the dielectric shell until a resonant shell thickness is reached. We provide a simple description of how to reach this strongly absorbing resonance condition, making our results easy to apply for a broad wavelength range and a multifold of semiconductor and dielectric coating material combinations.

Keywords

Nanowire array InAs absorption photovoltaics core-shell Al2O3 coating 

Supplementary material

12274_2012_270_MOESM1_ESM.pdf (781 kb)
Supplementary material, approximately 784 KB.

Copyright information

© Tsinghua University Press and Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Nicklas Anttu
    • 1
  • Kousar L. Namazi
    • 1
  • Phillip M. Wu
    • 1
  • Pengfei Yang
    • 2
  • Hongxing Xu
    • 1
    • 2
  • H. Q. Xu
    • 1
    • 3
  • Ulf Håkanson
    • 1
    • 2
  1. 1.Division of Solid State Physics/The Nanometer Structure Consortium at Lund University (nmC@LU)LundSweden
  2. 2.Beijing National Laboratory for Condensed Matter Physics, Institute of PhysicsChinese Academy of SciencesBeijingChina
  3. 3.Department of Electronics and Key Laboratory for the Physics and Chemistry of NanodevicesPeking UniversityBeijingChina

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