Nanophotonics in absorbing IIIV nanowire arrays
(2013) Abstract
 We have studied the interaction of light with an array of vertically oriented IIIV
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 smalldiameter nanowires and by geometrical optics
for largediameter... (More)  We have studied the interaction of light with an array of vertically oriented IIIV
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 smalldiameter nanowires and by geometrical optics
for largediameter 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 nanowirearray solar cell
showed an efficiency of 13.8 % and converted more than 70 % of the abovebandgap
photons into electronhole pairs that contributed to the shortcircuit 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 largearea arrays. The accuracy of the method is comparable to
that of scanning electron microscopy. Furthermore, we have developed tools for
studying the crystalphase dependent optical response of IIIV 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:
http://lup.lub.lu.se/record/3768636
 author
 Anttu, Nicklas ^{LU}
 supervisor
 opponent

 Professor Yablonovitch, Eli, University of California, Berkeley, USA
 organization
 publishing date
 2013
 type
 Thesis
 publication status
 published
 subject
 keywords
 IIIV 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
 20130614 14:00
 ISBN
 9789174735505
 language
 English
 LU publication?
 yes
 id
 26c12e93f2a9484c897b1c524b0e87fe (old id 3768636)
 date added to LUP
 20130522 14:52:53
 date last changed
 20160919 08:45:17
@phdthesis{26c12e93f2a9484c897b1c524b0e87fe, abstract = {We have studied the interaction of light with an array of vertically oriented IIIV<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 smalldiameter nanowires and by geometrical optics<br/><br> for largediameter 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 nanowirearray solar cell<br/><br> showed an efficiency of 13.8 % and converted more than 70 % of the abovebandgap<br/><br> photons into electronhole pairs that contributed to the shortcircuit 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 largearea 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 crystalphase dependent optical response of IIIV 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 = {9789174735505}, keyword = {IIIV semiconductor materials,Nanophotonics,nanowires,electromagnetic modeling,Fysicumarkivet A:2013:Anttu}, language = {eng}, pages = {200}, school = {Lund University}, title = {Nanophotonics in absorbing IIIV nanowire arrays}, year = {2013}, }