Die Erforschung von Quantenpunkten mit ihren quantisierten, atomähnlichen Zuständen, bietet eine Vielzahl von Möglichkeiten auf dem Weg zum Quantencomputer und für Anwendungen wie Einzelphotonenquellen und Quantenpunktlasern. Vorangegangene Studien haben grundlegend gezeigt, wie Quantenpunkte in Halbleiterresonatoren integriert und mit diesen gekoppelt werden können. Dazu war es zum einen notwendig, die Quantenpunkte und ihr epitaktisches Wachstum besser zu verstehen und zu optimieren. Zum anderen mussten die Bragg-Resonatoren optimiert werden, sodass Güten von bis zu 165.000 realisiert werden konnten. Eingehende Studien dieser Proben zeigten im Anschluss einen komplexeren Zusammenhang von Q-Faktor und Türmchendurchmesser. Man beobachtet eine quasi periodische Oszillation des Q-Faktors mit dem Pillar Durchmesser. Ein Faktor für diese Oszillation ist die Beschaffenheit der Seitenflanken des Resonatortürmchens, bedingt durch die unterschiedlichen Eigenschaften von AlAs und GaAs bei der Prozessierung der Türmchen. Darüber hinaus wurden in der Folge auf den Grundlagen dieser Strukturen sowohl optisch als auch elektrisch gepumpte Einzelphotonenquellen realisiert. Da in diesen Bauteilen auch die Lage des Quantenpunkts innerhalb des Resonatortürmchens einen erheblichen Einfluss auf die Effizienz der Kopplung zwischen Resonator und Quantenpunkt hat, war das weitere Ziel, die Quantenpunkte kontrolliert zu positionieren. Mit einer gezielten Positionierung sollte es möglich sein, ein Resonatortürmchen direkt über dem Quantenpunkt zu plazieren und den Quantenpunkt somit in das Maximum der optischen Mode zu legen. Besondere Herausforderung für die Aufgabenstellung war, Quantenpunkte in einem Abstand von mind. der Hälfte des angestrebten Türmchendurchmessers, d.h 0,5 μm bis 2 μm, zu positionieren. Die Positionierung musste so erfolgen, dass nach dem Wachstum eines AlAs/GaAs DBR Spiegel über den Quantenpunkten, Resonatortürmchen zielgenau auf die Quantenpunkte prozessiert werden können. Es wurden geeignete Prozesse zur Strukturierung eines Lochgitters in die epitaktisch gewaschene Probe mittels Elektronenstrahllithographie entwickelt. Für ein weiteres Wachstum mittels Molekularstrahlepitaxie, mussten die nasschemischen Reinigungsschritte sowie eine Reinigung mit aktivem Wasserstoff im Ultrahochvakuum optimiert werden, sodass die Probe möglichst defektfrei überwachsen werden konnte, die Struktur des Lochgitters aber nicht zerstört wurde. Es wurden erfolgreich InAs-Quantenpunkte auf die vorgegebene Struktur positioniert, erstmals in einem Abstand von mehreren Mikrometern zum nächsten Nachbarn. Eine besondere Herausforderung war die Vorbereitung für eine weitere Prozessierung der Proben nach Quantenpunktwachstum. Eine Analyse mittels prozessierten Goldkreuzen, dass 30 % der Quantenpunkte innerhalb von 50 nm und 60 % innerhalb von 100 nm prozessiert wurden. In der Folge wurde mit der hier erarbeiteten Methode Quantenpunkte erfolgreich in DBR-Resonatoren sowie photonische Kristalle eingebaut Die gute Abstimmbarkeit von Quantenpunkten und die bereits gezeigte Möglichkeit, diese in Halbleiterresonatoren einbinden zu können, machen sie auch interessant für die Anwendung im Telekommunikationsbereich. Um für Glasfasernetze Anwendung zu finden, muss jedoch die Wellenlänge auf den Bereich von 1300 nm oder 1550 nm übertragen werden. Vorangegangene Ergebnisse kamen allerdings nur knapp an die Wellenlänge von 1300nm. Eine fu ̈r andere Bauteile sowie für Laserdioden bereits häufig eingesetzte Methode, InAs-Quantenpunkte in den Bereich von Telekommunikationswellenla ̈ngen zu verschieben, ist die Verwendung von Stickstoff als weiteres Gruppe-V-Element. Bisherige Untersuchungen fokussierten sich auf Anwendungen in Laserdioden, mit hoher Quantenpunktdichte und Stickstoff sowohl in den Quantenpunkten als in den umgebenen Strukturen. Da InAsN-Quantenpunkte in ihren optischen Eigenschaften durch verschiedene Verlustmechanismen leiden, wurde das Modell eines Quantenpunktes in einem Wall (Dot-in-Well) unter der Verwendung von Stickstoff weiterentwickelt. Durch gezielte Separierung der Quantenpunkte von den stickstoffhaltigen Schichten, konnte e eine Emission von einzelnen, MBE-gewachsenen InAs Quantenpunkten von über 1300 nm gezeigt werden. Anstatt den Stickstoff direkt in die Quantenpunkte oder unmittelbar danach in die Deckschicht ein zu binden, wurde eine Pufferschicht ohne Stickstoff so angepasst, dass die Quantenpunkte gezielt mit Wellenlängen größer 1300 nm emittieren. So ist es nun möglich, die Emission von einzelnen InAs Quantenpunkten jenseits dieser Wellenlänge zu realisieren. Es ist nun daran, diese Quantenpunkte mit den beschriebenen Mikroresonatoren zu koppeln, um gezielt optisch und elektrisch gepumpte Einzelphotonenquellen für 1300nm zu realisieren. / The research of quantum dots with their quantized, atom-like states provides many possibilities for quantum computing and for application in technologies like single photon sources and quantum dot lazers. Previous studies have demonstrated how quantum dots can be integrated with and linked to semiconductor resonator. For this reason, it is necessary to better understand and optimize the epitaxial growth of quantum dots. Within the context of this work, the Bragg-Resonators must be optimized so that Q factors of up to 165.000 can be realized. Extensive studies of these samplings indicate a complex dependency between Q factors and diameter of the micropillar. This is how a quasi-periodic Q factor oscillation looks. One factor for these oscillations is the composition of the side flanks of the resonator micropillars, caused by the various properties of AIAs and GaAs during processing the micropillar. In addition, both optically and electrically pumped single photon sources have been realized on the basis of this structure. Due to the fact that the position of the quantum dot within the resonator micropillar has a significant effect on the efficiency of the coupling between the resonator and the quantum dot, a further goal was to control the position of the quantum dot. With a precise positioning, it should be possible to place a micropillar directly over a quantum dot, thus the quantum dot is located in the center of the pillar mode. A particular challenge in the scope of work was to position the quantum dots with a distance of at least half of the target micropillar diameter,in other words, between 0,5μm and 2μm. The positioning must be done in such a way so that a AIAs/GaAs DBR micropillar can be processed over the quantum dot. Therefore processes were developed to place a lattice of holes on an MBE grown sample via Electron Beam Lithography. The lithographical process was optimized by additional steps of wet chemical cleaning, and cleaning with hydrogen under ultra high vacuum, to avoid defects during MBE overgrowth. InAs quantum dots have positions on a given structure in a distance of several micrometers to each other. It could be proved by processing gold pattern, that 30% of the quantum dots are placed within 50 nm precision and 60% within 100 nm . In the following work quantum dots have been placed in DBR micro pillars and photonic crystals. Because quantum dots have a wide spectral range and because they can be integrated in micropillars, they are also of interest for applications within telecommunication systems. Therefore the spectral range around 1300 nm and 1550 nm has to be re- ached to link them to fiber cable. Former studies have shown results tight under 1300nm. Nitrogen is an additional way to get InAs quantum emitting at 1300nm at 8 K. Until now research for InAs quantum dots containing nitrogen was focused on high density dots for laser application. The Dot- In-A-Well design was transferred, in this work, to this problem by using nitrogen in a well above the quantum dots. With this development, single quantum dots, emitting above 1300nm at 8 K, have been grown for the first time. The next step would be to integrated this InAs Quantum dots with the nitrogen well, within the micro pillar to achieve single photon sources at 1300nm.

On-chip vibrating MEMS resonators with high frequency-Q product on par with that of the off-chip quartz crystals have attracted lots of attention from both academia and industry for applications on sensing, signal processing, and wireless communication. Up to now, several approaches for monolithic integration of MEMS and transistors have been demonstrated. Vibrating micromechanical disk resonators which utilize electroplated nickel as the structural material along with either a solid-gap high-k dielectric capacitive transducer or a piezoelectric transducer have great potential to offer unprecedented performance and capability of seamless integration with integrated circuits. Despite the frequency drift problems encountered in early attempts to use nickel as a structural material in MEMS gyroscopes, this low temperature nickel electroplating technology is amenable to post-transistor planar integration. The nickel microstructure is formed through the photoresist molding and electroplating process which enables the microstructure to have extremely high aspect ratio while retaining the overall process temperature under 60ºC. This temperature is low enough to allow the RF MEMS devices to be fabricated directly on top of foundry IC chips, thus enabling post-transistor monolithic integration with minimum parasitics. In addition, the electroplating setup for nickel deposition can be much cheaper as compared to the other deposition facilities (e.g., PVD, CVD, etc). However, as the dimensions of the resonators are shrunk to µm range, several issues have come forth such as higher motional resistance and lower power handling ability. In order to reduce the motional resistance, high permittivity material is employed to form a solid capacitive gap instead of an air gap. As compared to the air gap, ease of the process, better stability and elimination of the particles are the additional benefits of using the solid gap. Therefore, an ultra-thin high-k dielectric layer with atomically controlled thickness down to sub-nm range can be deposited under 100ºC on the vertical sidewall of the device structure by using ALD processing technology. This enhances the efficiency of the capacitive transducer enormously, thus reducing the characteristic motional resistance of the device. This research project explored the idea of applying low temperature process of electroplated nickel and high-k solid-gap as well as partially-filled air-gap capacitive transducers. To further reduce the motional impedance, electromechanically-coupled resonator arrays have been implemented. Furthermore, the linearity of solid-gap versus partially-filled air-gap resonators has been studied through a modeling approach for RF applications. In the meanwhile, this work also investigated electroplated nickel as a structural material for piezoelectrically-transduced resonators to demonstrate piezoelectric-on-nickel resonators with low temperature process. The thin film piezoelectric resonators can achieve high resonance frequency when increasing the piezoelectric film thickness and scaling down the device size. However, the sputtered piezoelectric films have very low deposition rate which limits the thickness to a couple of microns or less. Moreover, the yield of piezoelectric resonators is restricted after the releasing process since the stress of the thin films usually causes the structural layer to buckle or fracture. Thus, the development of piezoelectric-on-substrate resonators is an alternative solution to resolve the aforementioned issues. The previous work has been done by using single crystal silicon or nano-crystalline diamond (NCD) as resonator structural materials due to their high acoustic velocity and low loss. However, the deposition temperature for thin film silicon and diamond is too high to be allowable thermal budget of ICs. Therefore, electroplated nickel is also a reasonable substitute for silicon and diamond substrates while realizing high frequency and moderate Q. Furthermore, it is observed that a localized annealing process through Joule heating can be adopted to significantly improve the effective mechanical quality factor for the ZnO-on-nickel resonators. This work successfully demonstrated the ZnO-on-nickel piezoelectrically-actuated MEMS resonators and resonator arrays with frequencies ranging from a few megahertz to 1.5 GHz by using IC compatible low temperature process.

<p> In the work of this doctoral dissertation a new resonator sensor technique, first presented in 1989, has been further developed and evaluated with focus on technical characteristics and applications within the medical field.</p><p> In a first part a catheter-type tactile sensor using the resonator sensor technique was evaluated in a silicone model and applied to human prostate in vitro. The main finding was that different histological compositions of prostate tissue correlated with the frequency shift, .fS, of the resonator sensor and that the common property was the hardness of the tissue. The results indicated that hardness of the prostate tissue, and maybe hardness of human tissue in general, can be expressed according to a cone penetration standard (DIN ISO 2137) and that the hardness can be measured with this tactile sensor system. The tissue hardness application for the resonator sensor technique has to be further developed and evaluated in a larger study. The study also produced results that has led to the basic understanding of the resonator sensor system. One important result was that .fS of the sensor system was related to the contact area between sensor and sample. This indicated that the resonance sensor could be used for contact area measurement.</p><p> In a second part, containing three studies, the area-sensing capability from the first study was utilised in the development and evaluation of the applanation resonator sensor (ARS) for measurement of intraocular pressure (IOP). For the purpose of evaluating IOP-tonometers, an in vitro pig-eye model was developed, and it was shown that a saline column connected to the vitreous chamber could be used successfully to induce variations in IOP.</p><p> A ARS sensor with a flat contact surface was applied onto the cornea with constant force and .fS was measured. A mathematical model based on the Imbert-Fick law and the assumption that .fS was linearly related to contact area was proposed and verified with a convincing result. IOP measured with the ARS correlated well (r=0.92, n=360) with the IOP elicited by a saline column.</p><p> The ARS in a constant-force arrangement was evaluated on healthy human subjects in vivo. The results verified the sensor principle but revealed a nonnegligible source of error in off-centre positioning between the sensor and cornea. The sensor probe was redesigned and evaluated in the in vitro model. The new probe, with a spherical contact surface against the eye reduced the sensitivity to off-centre positioning. It was also shown that a .fS normalisation procedure could reduce the between-eye differences.</p><p> The ARS method for IOP measurement was further developed using combined continuous force and area measurement during the dynamic phase when the sensor initially contacts the cornea. A force sensor was included with the resonator sensor in one probe. Evaluation was performed with the in vitro pig-eye model. The hypothesis was that the IOP could be deduced from the differential change of force and area during that phase. The study showed good accuracy and good reproducibility with a correlation of r=0.994 (n=414) between measured pressure in the vitreous chamber and IOP according to the ARS. Measurement time was short, 77 ms after initial contact. Problems with inter-eye differences and low resolution at high pressures were reduced. The ARS method is the first to combine simultaneous, continuous sampling of both parameters included in the applanation principle. Consequently, there is a potential for reducing errors in the clinical IOP tonometry. </p>

Part I - We have designed a binary metallic alloy for nanoscale resonator applications. We used magnetron sputtering to deposit films with different stoichiometries of aluminum and molybdenum and then characterized the microstructure and physical properties of each film. A structure zone map is proposed to describe the dependence of surface and bulk structure on composition. We then fabricated proof of principle resonators from the Al-32 at%Mo composition, selected for its optimized physical properties. An optical interferometer was used to characterize the frequency response of our resonators. Part II - We investigate the growth of faceted polycrystalline thin films with modeling and simulations. A new analytic model is derived for the case of orientation dependent facet growth velocity and the dependence of growth on initial grain orientations is explicitly calculated. Level set simulations were used to both confirm this analytic model and extend it to include various angular flux distributions, corresponding to different deposition methods. From these simulations, the effects of self-shadowing on polycrystalline film growth are quantitatively evaluated. / Materials Engineering

In the work of this doctoral dissertation a new resonator sensor technique, first presented in 1989, has been further developed and evaluated with focus on technical characteristics and applications within the medical field. In a first part a catheter-type tactile sensor using the resonator sensor technique was evaluated in a silicone model and applied to human prostate in vitro. The main finding was that different histological compositions of prostate tissue correlated with the frequency shift, .fS, of the resonator sensor and that the common property was the hardness of the tissue. The results indicated that hardness of the prostate tissue, and maybe hardness of human tissue in general, can be expressed according to a cone penetration standard (DIN ISO 2137) and that the hardness can be measured with this tactile sensor system. The tissue hardness application for the resonator sensor technique has to be further developed and evaluated in a larger study. The study also produced results that has led to the basic understanding of the resonator sensor system. One important result was that .fS of the sensor system was related to the contact area between sensor and sample. This indicated that the resonance sensor could be used for contact area measurement. In a second part, containing three studies, the area-sensing capability from the first study was utilised in the development and evaluation of the applanation resonator sensor (ARS) for measurement of intraocular pressure (IOP). For the purpose of evaluating IOP-tonometers, an in vitro pig-eye model was developed, and it was shown that a saline column connected to the vitreous chamber could be used successfully to induce variations in IOP. A ARS sensor with a flat contact surface was applied onto the cornea with constant force and .fS was measured. A mathematical model based on the Imbert-Fick law and the assumption that .fS was linearly related to contact area was proposed and verified with a convincing result. IOP measured with the ARS correlated well (r=0.92, n=360) with the IOP elicited by a saline column. The ARS in a constant-force arrangement was evaluated on healthy human subjects in vivo. The results verified the sensor principle but revealed a nonnegligible source of error in off-centre positioning between the sensor and cornea. The sensor probe was redesigned and evaluated in the in vitro model. The new probe, with a spherical contact surface against the eye reduced the sensitivity to off-centre positioning. It was also shown that a .fS normalisation procedure could reduce the between-eye differences. The ARS method for IOP measurement was further developed using combined continuous force and area measurement during the dynamic phase when the sensor initially contacts the cornea. A force sensor was included with the resonator sensor in one probe. Evaluation was performed with the in vitro pig-eye model. The hypothesis was that the IOP could be deduced from the differential change of force and area during that phase. The study showed good accuracy and good reproducibility with a correlation of r=0.994 (n=414) between measured pressure in the vitreous chamber and IOP according to the ARS. Measurement time was short, 77 ms after initial contact. Problems with inter-eye differences and low resolution at high pressures were reduced. The ARS method is the first to combine simultaneous, continuous sampling of both parameters included in the applanation principle. Consequently, there is a potential for reducing errors in the clinical IOP tonometry.

This thesis reports on the use of sputter-deposited zinc-oxide as a transduction mechanism to actuate and sense single crystal silicon (SCS) microelectromechanical (MEMS) resonators. Low frequency prototypes of piezo-on-silicon resonators with operating frequencies in the range of hundreds of kHz were implemented using micromechanical single crystal silicon clamped-clamped beam resonators. The resonators reported here extend the frequency of this technology into very high frequency (VHF range) by using in-plane length extensional bulk resonant modes. This thesis outlines the design, implementation and characterization of high-frequency single crystal silicon (SCS) block resonators with piezoelectric electromechanical transducers. The resonators are fabricated on 4m thick SOI substrates and use sputtered ZnO as the piezo material. The centrally supported block resonators operate in their first and higher order length extensional bulk modes with high quality factor (Q). Measurement results are in good agreement with the developed ANSYS simulations.

Photonic crystals (PCs) are nano-structured materials in which a periodic variation of the dielectric constant of the material results in a photonic band gap. By introducing defects into PCs, it is possible to build waveguides that can channel light along certain paths. It is also possible to construct micro-cavities that can localize photons in extremely small volumes. In this dissertation, to begin with, we computed the photonic crystals dispersion relations and found the photonic band gap (PBG) by the plane wave expansion method (PWE) in the frequency domain. Then, the finite difference time domain method (FDTD) along with the perfectly matched layer boundary conditions was adopted to solve Maxwell¡¦s equations, equivalent to simulate the movement behavior of the Photonic crystals. By properly varying the size of the defect on the PCs, it could really drop the particular wavelengths and guide them to output channels by PCs waveguides. We proposed the structures that would function as Wavelength-Division-Multiplexer (WDM). Secondly, coupled cavity waveguide of PC was used to control group velocity that achieved the slow light property. By calculating dispersion curve with PWE, we obtained group velocity characteristics in PCs waveguide. Meanwhile, we designed a novel Time-Division-Multiplexer (TDM) system by controlling the group velocity characteristics. Finally, we designed cascade ring resonators and expected to obtain an extendable delay line. Conventional delay line devices are propagating in a long waveguide to obtain the delay line property. An excellent delay line and ultra-small size properties are expected in the proposed structure. Because nano-technology has been making great progress steadily, it surely can be used to demonstrate a practical breakthrough in which the devices based on the PC integrated circuits are realized. These devices will be a potential key component in the applications of ultra-high-speed and ultra-high-capacity optical communications and optical data processing systems.

Dielectric resonator antennas(DRAs) offer some attractive characteristics over conventional microstrip antennas, such as small size, low profile, light weight, ease of excitation, and high radiation efficiency at higher frequency bands. Since DRAs attract more and more attention, theoretical analysis have been insufficient to simulate various configurations of dielectric resonator antennas. Therefore some researchers introduce numerical methods to analyze DRAs, such as Finite Difference Time Domain (FDTD) method, Method of Moment (MoM), Finite Element Method (FEM). In this author, we apply two kinds of methods, including FDTD and MoM, to analysis DRA and compare the results applied these two methods. Then we simulate various configurations of dielectric resonator antennas using FDTD method. About designing the DRA construction, in this author we applied an equivalent approach to solve approximate dimensions of DRAs, and then we obtain accurate dimensions using FDTD method. In this author¡Aa DRA work at 5.8GHz have been proposed, then we using a L-shaped patch to increase impedance bandwidth. Above all, we hope to built a fast and accurate procedure to solve the resonant frequency, bandwidth, and far field pattern of DRAs. And to supply the engineer to reduce time consume in design DRAs.

The permeation of CMOS technology to radio frequencies and beyond has fuelled an urgent need for a diverse array of passive and active circuits that address the challenges of rapidly emerging wireless applications. While traditional analog based design approaches satisfy some applications, the stringent requirements of newly emerging applications cannot necessarily be addressed by existing design ideas and compel designers to pursue alternatives. One such alternative, an amalgamation of microwave and analog design techniques, is pursued in this work. A number of passive and active circuits have been designed using a combination of microwave and analog design techniques. For passives, the most crucial challenge to their CMOS implementation is identified as their large dimensions that are not compatible with CMOS technology. To address this issue, several design techniques – including multi-layered design and slow wave structures – are proposed and demonstrated through experimental results after being suitably tailored for CMOS technology. A number of novel passive structures - including a compact 10 GHz hairpin resonator, a broadband, low loss 25-35 GHz Lange coupler, a 25-35 GHz thin film microstrip (TFMS) ring hybrid, an array of 0.8 nH and 0.4 nH multi-layered high self resonant frequency (SRF) inductors are proposed, designed and experimentally verified. A number of active circuits are also designed and notable experimental results are presented. These include 3-10 GHz and DC-20 GHz distributed low noise amplifiers (LNA), a dual wideband Low noise amplifier and 15 GHz distributed voltage controlled oscillators (DVCO). Distributed amplifiers are identified as particularly effective in the development of wideband receiver front end sub-systems due to their gain flatness, excellent matching and high linearity. The most important challenge to the implementation of distributed amplifiers in CMOS RFICs is identified as the issue of their miniaturization. This problem is solved by using integrated multi-layered inductors instead of transmission lines to achieve over 90% size compression compared to earlier CMOS implementations. Finally, a dual wideband receiver front end sub-system is designed employing the miniaturized distributed amplifier with resonant loads and integrated with a double balanced Gilbert cell mixer to perform dual band operation. The receiver front end measured results show 15 dB conversion gain, and a 1-dB compression point of -4.1 dBm in the centre of band 1 (from 3.1 to 5.0 GHz) and -5.2 dBm in the centre of band 2 (from 5.8 to 8 GHz) with input return loss less than 10 dB throughout the two bands of operation.

In this study, AlN films are deposited using reactive RF magnetron sputter on various bottom metals, such as Mo, Al and Pt. The orientation of piezoelectric AlN thin films on different bottom electrode materials are investigated. Moreover, the acoustic Bragg reflectors deposited by DC magnetron sputter are composed of alternating layers of high and low acoustic impedance materials. To improve the performance of the reflectors, rapid thermal anneal and deposition process control over roughness of the thin film are also investigated. The resonance characteristics are improved obviously by deposition process control over thin films. The roughness control is the key factor of good frequency responses of SMR. In addition, the more layer of the reflectors the better the frequency response we obtained. The frequency responses of SMR are slightly improved by rapid thermal annealing procsess. Although defects in the thin films would be eliminated, nevertheless the thin film roughness became worse after annealing. This phenomenon would limit the improvement of frequency responses.