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Large photocurrents in GaN porous structures with a redshift of the photoabsorption edge

Authors
  • Sato, Taketomo1
  • Kumazaki, Yusuke1
  • Kida, Hirofumi1
  • Watanabe, Akio1
  • Zenji Yatabe1
  • Matsuda, Soichiro1
Type
Published Article
Journal
Semiconductor Science and Technology
Publisher
IOP Publishing
Publication Date
Oct 12, 2015
Accepted Date
Jul 12, 2015
Volume
31
Identifiers
DOI: 10.1088/0268-1242/31/1/014012
Source
MyScienceWork
License
Green

Abstract

Photoresponse and photoabsorption properties of GaN porous structures were investigated by measuring photocurrent and spectroscopic photoabsorption under monochromatic light with various wavelengths. The measured photocurrents on the porous GaN electrodes were larger than those on the planar electrodes due to the unique features of the former electrode, such as large surface area and low photoreflectance properties. Moreover, the photocurrents were observed even under illumination with wavelength of 380 nm, corresponding to photon energy of 3.26 eV, which is 130 meV lower than the bandgap energy of bulk GaN. A potential simulation revealed that a high-electric field was induced at the pore tips due to modification of the potential in the porous structures. The observed redshift of the photoabsorption edge can be qualitatively explained by the Franz–Keldysh effect.

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