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Nanophotonics in absorbing III-V nanowire arrays

Anttu, Nicklas LU (2013)
Abstract
We have studied the interaction of light with an array of vertically oriented III-V

semiconductor nanowires both theoretically and experimentally. For the theoretical

studies, electromagnetic modeling has been employed. This modeling shows that with

proper tuning of the nanowire diameter, the absorption per volume semiconductor

material can be 20 times higher in the nanowires than in a corresponding bulk

semiconductor sample. This enhancement occurs when nanophotonic resonances show

up in the nanowires. We have shown that the optical response of a nanowire array can

be described by electrostatics for small-diameter nanowires and by geometrical optics

for large-diameter... (More)
We have studied the interaction of light with an array of vertically oriented III-V

semiconductor nanowires both theoretically and experimentally. For the theoretical

studies, electromagnetic modeling has been employed. This modeling shows that with

proper tuning of the nanowire diameter, the absorption per volume semiconductor

material can be 20 times higher in the nanowires than in a corresponding bulk

semiconductor sample. This enhancement occurs when nanophotonic resonances show

up in the nanowires. We have shown that the optical response of a nanowire array can

be described by electrostatics for small-diameter nanowires and by geometrical optics

for large-diameter nanowires. None of these two limit cases showed resonances,

motivating the interest for the intermediate nanophotonic regime where the diameter

of the nanowires is comparable to the wavelength of the incident light.



Supported by theoretical analysis, we have shown experimentally a resonant

photodetection response in an InAsSb nanowire array in the infrared region, which is

of potential interest for thermal imaging and chemical analysis. Furthermore, we have

demonstrated a solar cell based on InP nanowires. The nanowire-array solar cell

showed an efficiency of 13.8 % and converted more than 70 % of the above-bandgap

photons into electron-hole pairs that contributed to the short-circuit current, even

though the nanowires covered only 12 % of the surface.



By combining the electromagnetic modeling with reflectance measurements, we have

developed an optical method for simultaneously measuring both the diameter and the

length of nanowires in large-area arrays. The accuracy of the method is comparable to

that of scanning electron microscopy. Furthermore, we have developed tools for

studying the crystal-phase dependent optical response of III-V materials. The studies

showed that a tuning of the crystal phase, which is possible in the nanowire geometry,

can be used for enabling and disabling strongly absorbing nanophotonic resonances in

nanowire arrays. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Yablonovitch, Eli, University of California, Berkeley, USA
organization
publishing date
type
Thesis
publication status
published
subject
keywords
III-V semiconductor materials, Nanophotonics, nanowires, electromagnetic modeling, Fysicumarkivet A:2013:Anttu
pages
200 pages
defense location
Lecture Hall Rydbergsalen, Department of Physics, Professorsgatan 1, Lund University Faculty of Engineering
defense date
2013-06-14 14:00
ISBN
978-91-7473-550-5
language
English
LU publication?
yes
id
26c12e93-f2a9-484c-897b-1c524b0e87fe (old id 3768636)
date added to LUP
2013-05-22 14:52:53
date last changed
2016-09-19 08:45:17
@misc{26c12e93-f2a9-484c-897b-1c524b0e87fe,
  abstract     = {We have studied the interaction of light with an array of vertically oriented III-V<br/><br>
semiconductor nanowires both theoretically and experimentally. For the theoretical<br/><br>
studies, electromagnetic modeling has been employed. This modeling shows that with<br/><br>
proper tuning of the nanowire diameter, the absorption per volume semiconductor<br/><br>
material can be 20 times higher in the nanowires than in a corresponding bulk<br/><br>
semiconductor sample. This enhancement occurs when nanophotonic resonances show<br/><br>
up in the nanowires. We have shown that the optical response of a nanowire array can<br/><br>
be described by electrostatics for small-diameter nanowires and by geometrical optics<br/><br>
for large-diameter nanowires. None of these two limit cases showed resonances,<br/><br>
motivating the interest for the intermediate nanophotonic regime where the diameter<br/><br>
of the nanowires is comparable to the wavelength of the incident light.<br/><br>
<br/><br>
Supported by theoretical analysis, we have shown experimentally a resonant<br/><br>
photodetection response in an InAsSb nanowire array in the infrared region, which is<br/><br>
of potential interest for thermal imaging and chemical analysis. Furthermore, we have<br/><br>
demonstrated a solar cell based on InP nanowires. The nanowire-array solar cell<br/><br>
showed an efficiency of 13.8 % and converted more than 70 % of the above-bandgap<br/><br>
photons into electron-hole pairs that contributed to the short-circuit current, even<br/><br>
though the nanowires covered only 12 % of the surface.<br/><br>
<br/><br>
By combining the electromagnetic modeling with reflectance measurements, we have<br/><br>
developed an optical method for simultaneously measuring both the diameter and the<br/><br>
length of nanowires in large-area arrays. The accuracy of the method is comparable to<br/><br>
that of scanning electron microscopy. Furthermore, we have developed tools for<br/><br>
studying the crystal-phase dependent optical response of III-V materials. The studies<br/><br>
showed that a tuning of the crystal phase, which is possible in the nanowire geometry,<br/><br>
can be used for enabling and disabling strongly absorbing nanophotonic resonances in<br/><br>
nanowire arrays.},
  author       = {Anttu, Nicklas},
  isbn         = {978-91-7473-550-5},
  keyword      = {III-V semiconductor materials,Nanophotonics,nanowires,electromagnetic modeling,Fysicumarkivet A:2013:Anttu},
  language     = {eng},
  pages        = {200},
  title        = {Nanophotonics in absorbing III-V nanowire arrays},
  year         = {2013},
}