4 research outputs found
ALUMINUM ZINC OXIDE (AZO) OPTIMIZATION PROCESS FOR USE IN OPTICALLY TRANSPARENT ANTENNAS
The importance of having an optimal material for fabricating Optically Transparent Antennas (OTAs) is crucial for designing highly efficient antennas that can be integrated with photovoltaics. Transparent Conductor Oxides (TCOs) are promising for OTA fabrication due to their capability of being simultaneously transparent at optical frequencies and conductive within the radio frequency (RF) range. In this work, a new material was developed and optimized to be used for fabricating an optically transparent antenna on a solar cell. Aluminum and Zinc Oxide were co-sputtered onto Si and onto a polycrystalline photovoltaic cell and then annealed between 350°C and 450°C for 24 and 48 h in N2 ambient. The annealing process ensured the formation of the Aluminum Zinc Oxide (AZO) with a DC conductivity of 3.48Ăă10ă^5 Sâcm and a transparency of 86% for a thickness between 350 and 750 nm. This new AZO material was shown to be capable of yielding high levels of conductivity at RF frequencies and excellent transmittance at optical frequencies. The material was tested and validated by performing RF characterization, and by fabricating and testing different optically transparent antennas. The details of the fabrication process, its optimization process, the design of the optical antennas are presented in details and discussed. The material was tested and validated by performing RF characterization, and by fabricating and testing different OTA designs
Optically Transparent Antennas and Filters for Smart City Communication
Incremental usage of mobile devices demand a new generation of wireless networks (5G) to provide faster data rates, more reliable coverage, monitor city infrastructure usage, and increase network capacity. The frequencies proposed for the upcoming 5G network would result in shorter broadcast distances and network dead zones, countered by incorporating transparent antennas into glass high rises. Transparent antennas possess, however a major challenge: low gain. This lower gain can be countered by means of employing antennas in an antenna array, boosting the gain and even giving the array the ability to beam form for the upcoming 5G network. The 5G dead zones can be countered with strategically placed transparent reflectors embedded into the glass surfaces of city high-rises.
This dissertation shows there are significant effects due to the transparent antennasâ carrier concentration and film thickness. Changes in film conductivity and thicknesses results in shifts for filter and antenna resonances. A 4x1 GZO antenna array was constructed to operate at 5.8 GHz, and the results show approximately 10dBi of lower aperture gain between a copper version of the array and the GZO version of the array. However, the 4x1 GZO array shows an approximate 12dBi increase in gain over a single GZO antenna element.
The technology developed in this dissertation has a broader impact other than for smart cities and the upcoming 5G network. Transparent antenna arrays offer sight insensitive military communication systems and eye-worn medical and commercial devices to monitor eye health and other various health signs
Spin Manipulation of the Nitrogen Vacancy Center and its Applications
Das Stickstoff-Fehlstellen-Zentrum (NV-Zentrum) in Diamant ist eines der vielver-
sprechendsten Spinsysteme fĂŒr Anwendungen im Bereich Quanten-Computing,
-Information und -Sensorik. Die AbhÀngigkeit der FluoreszenzintensitÀt vom Spinzu-
stand ermöglicht dabei das rein optische Auslesen des Spinzustandes. FĂŒr alle
Anwendungen, die auf aktive Spinmanipulation angewiesen sind, ist Mikrowellen-
strahlung unverzichtbar. Die FÀhigkeit, den Spinzustand von NV-Zentren vollstÀndig
zu kontrollieren, wird durch die Richtung, IntensitÀt und Polarisation der Mikrow-
ellenstrahlung deïŹniert. Es gibt verschiedene AnsĂ€tze, um geeignete Mikrowellen-
strahlung zu erzeugen, aber oft ist die FeldintensitÀt zu gering oder es gibt andere
EinschrÀnkungen, z.B. eine geringe Frequenzbandbreite.
Im ersten Teil meiner Arbeit untersuche ich transparente Leiter auf Basis von Indium-
Zinn-Oxid (ITO), um die Mikrowellenansteuerung von NV-Zentren zu optimieren.
Dabei wird eine detaillierte Analyse von ITO auf Diamant bezĂŒglich einzelner
NV-Zentren vorgestellt. Ein mathematisches Modell wurde entwickelt, um die
Feldverteilung vorherzusagen. ZusÀtzlich wird eine Methode zur Kontrolle der
Mikrowellenpolarisation mit einer transparenten ITO-Struktur vorgestellt, die zu
einer vollstĂ€ndigen Kontrolle des Spinzustands des NV-Zentrums fĂŒhrt. Weiterhin
werden Simulationen in Kombination mit einem analytischen Modell verwendet, um
optimale Mikrowellenparameter fĂŒr die Spinkontrolle vorherzusagen.
FĂŒr eine kommerzielle Anwendung von NV-Zentren als Magnetfeldsensor sind Pro-
duktionskosten und BauteilkomplexitÀt wichtige Faktoren, die in der Forschung
oft vernachlÀssigt werden. Der zweite Teil meiner Arbeit konzentriert sich da-
her auf einen mikrowellenfreien Ansatz zur Magnetometrie mit NV-Zentren. Der
EinïŹuss der Laseranregung auf den magnetischen Kontrast wird an einzelnen NV-
Zentren, Ensembles von NV-Zentren und Nano-Diamantpulver mit einer hohen NV-
Zentrenkonzentration dargestellt und nachfolgend zur Demonstration von isotropen
Magnetfeldmessung verwendet. AbschlieĂend wird die Anwendbarkeit durch die
Konstruktion eines Magnetfeldsensors aus Komponenten der Automobilbranche
gezeigt.The nitrogen vacancy center (NV center) in diamond is one of the most promising
spin systems for applications in quantum computing, information and sensing. The
dependency of the ïŹuorescence intensity on the spin state allows a purely optical
readout of the spin state. A green laser can be used to pump the NV center in the
spin ground state while microwave radiation can manipulate the spin state of the
NV center. For all applications depending on active spin manipulation, microwave
radiation is indispensable. The ability to fully control the spin state of NV centers is
deïŹned by direction, strength and polarization of the microwave radiation. Different
approaches exist to deliver the microwave radiation, but they often lack in strength
or have other restrictions, e.g. a small frequency band width.
In the ïŹrst part of my thesis, I investigate transparent conductors based on indium
tin oxide (ITO) to optimize microwave delivery. In this process a detailed analysis
of ITO on diamond concerning confocal microscopy through this transparent ïŹlm
is presented. A mathematical model was developed and tested to predict the ïŹeld
distribution in possible applications. Additionally a method to control microwave
polarization with a transparent ITO structure is shown which results in full spin
state control of the NV center. Furthermore simulations combined with a analytical
model are used to predict optimal microwave parameters for spin control.
For a commercial application of NV centers as a magnetic ïŹeld sensor, important
factors are production cost and device complexity which are often neglected in
research. The second part of my thesis therefore focuses on a microwave free
approach of NV center magnetometry for industry applications. The inïŹuence of
laser excitation on magnetic contrast was studied on single NV centers, ensembles
of NV centers and nano diamond powder with a high NV center concentration. The
ïŹndings were used to demonstrate isotropic magnetic ïŹeld sensing. Finally, the
applicability was shown by constructing a magnetic ïŹeld sensor from automotive
grade components