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Micro- and Nano-structured Metal Films for Optoelectronic Devices
KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.ORCID iD: 0000-0001-5170-265X
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Two types of micro and nanostructures of metal-dielectric films have been explored with the intention of improving optoelectronic devices.

The first part of the thesis concerns the design, fabrication and characterization of a metallic photonic crystal (mPhC). The mPhC was investigated with respect to fill factor, pitch size, metal thickness and bulk material to improve potential detectivity and responsivity when integrated on quantum dot infrared photo detectors (QDIPs). The pitch size was found to be the most important factor for the peak wavelength position of the bandpass while the bandwidth of the bandpass is formed by the combination of fill factor and metal thickness. The choice of substrate material was shown to only have a slight effect on the peak wavelength position through a positive relation with the refractive index of the substrate material.

In the second part of the thesis a thin-film multilayer optical resonator structure is explored with regards to its suitability as a transparent conductor. The structure was designed with a transfer matrix method. The figure of merit given by the transmissivity-over-resistance of the fabricated structure was shown to compare favorably to the notably common indium-tin-oxide (ITO) alloy currently used in optoelectronic applications as a transparent conductor. Although limited in transmission bandwidth, the silver-based multilayer structure can be valuable for optoelectronic applications and potentially replacing ITO owing to its relatively high peak transmissivity, improved conductivity as well as decreased fabrication costs.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. , iv, 44 p.
TRITA-ICT/MAP, 2014:09
National Category
Atom and Molecular Physics and Optics
URN: urn:nbn:se:kth:diva-145024ISBN: 978-91-7595-152-2OAI: diva2:715777
2014-05-27, Sal/Hall E, KTH - ICT, Isafjordsgatan 39, Kista, 14:00 (English)

QC 20140516

Available from: 2014-05-16 Created: 2014-05-06 Last updated: 2014-05-16Bibliographically approved
List of papers
1. Transmission of Infrared Radiation Through Metallic Photonic Crystal Structures
Open this publication in new window or tab >>Transmission of Infrared Radiation Through Metallic Photonic Crystal Structures
2013 (English)In: IEEE Photonics Journal, ISSN 1943-0655, Vol. 5, no 5, 4500608- p.Article in journal (Refereed) Published
Abstract [en]

Monolithic integration of a metallic photonic crystal (mPhC) structure onto semiconductor infrared (IR) photodetectors can enhance the detector performances. In order to experimentally investigate the parameters involved in optimizing the transmission spectra of the mPhC structures matching the detector operating wavelength in mid- and long-wave IR (MWIR and LWIR) regimes, square thin gold (Au) hole arrays having periodicities of 4.0, 3.6, 2.4, and 1.8 mu m with various fill factors were fabricated on Si or GaAs substrates in a wafer scale. The thicknesses of the Au films are 50, 100, and 200 nm, respectively. Through this systemic study, suitable mPhC structures were revealed that can be readily integrated onto our type-II InGaSb-based quantum dot MWIR and LWIR photodetectors.

Infrared photodetectors, plasmonics, subwavelength structures, metallic photonic crystal
National Category
Engineering and Technology
urn:nbn:se:kth:diva-133530 (URN)10.1109/JPHOT.2013.2278527 (DOI)000325410400012 ()2-s2.0-84885642400 (ScopusID)
VinnovaKnowledge FoundationSwedish Foundation for Strategic Research Swedish Research Council

QC 20131107

Available from: 2013-11-07 Created: 2013-11-06 Last updated: 2015-05-19Bibliographically approved
2. Double-resonator structure based on continuous silver thin films for transparent conductors
Open this publication in new window or tab >>Double-resonator structure based on continuous silver thin films for transparent conductors
Show others...
(English)Article in journal, Letter (Other academic) Submitted
Abstract [en]

A type of metal-dielectric multilayered structures is investigated theoretically and experimentally for achieving relatively wide-band transparency at visible frequencies with high electrical conductivity. The proposed structure comprises of two coupled metal-dielectric-metal planar optical resonators with metal layer thicknesses near to its skin depth. Simulations show that the maximum transmittance for visible light can easily reach 90% for silver-based structures. Experimentally we demonstrate such a sample that exhibits a transmission window with a bandwidth of 150nm and a maximum transmittance of 76% around 643nm wavelength at normal incidence. Its sheet resistance is measured to be less than 10Ω/☐, much smaller than that of common indium-tin-oxide films. Owing to their simple fabrication procedure as well as design flexibility, such a layered structure can serve as a compelling alternative as transparent conductors for optoelectronic devices, especially for liquid-crystal displays and light-emitting diodes.

National Category
Atom and Molecular Physics and Optics
urn:nbn:se:kth:diva-145021 (URN)

QS 2014

Available from: 2014-05-06 Created: 2014-05-06 Last updated: 2014-05-16Bibliographically approved

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Soltanmoradi, Reyhaneh
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