The development of monolithic silicon photonic systems has been the subject of intense research over the last decade. In addition to passive waveguiding structures suitable for DWDM applications, integration of electrical and optical functionality has yielded devices with the ability to dynamically attenuate, switch and modulate optical signals. Despite this significant progress, much higher levels of integration and increased functionality are required if silicon is to dominate as a substrate for photonic circuit fabrication as it does in the microelectronic industry. In particular, there exists a requirement for efficient silicon-based optical sources and detectors which are compatible with wavelengths of 1.3 and 1.5μm. While a great deal of work has focussed on the development of silicon-based optical sources, there has been less concentrated effort on the development of a simple, easily integrated detector technology. We describe here the design, fabrication and characterization of a wholly monolithic silicon waveguide optical detector, utilizing an integrated p+-u-n+ diode, which has significant response to optical signals at the communication wavelength of 1.54μm. Measurable infra-red response is induced via the controlled introduction of mid-gap electronic levels within the rib waveguide. This approach is completely compatible with ULSI fabrication. The requirement for the detectors to be integrated with a rib waveguide and hence the guarantee of a long optical signal-device interaction, results in electrical signals of several μAs, even for deep-levels with a small optical absorption cross-section. Further, the rise and fall time of the detectors is compatible with current monolithic, silicon device based, optical switching and modulation operating in the MHz regime. These results suggest that these detectors offer a cost-effective route to signal monitoring in integrated photonic circuits.

Direct wafer bonding was performed under medium vacuum condition. High bonding strength (larger than 20 MPa) is achieved at the bonding temperature of only 400°C, and the annealing time for complete bonding is less than 5 hours. The bonding efficiency (percentage of the bonded area over entire wafer area) of the medium vacuum wafer bonding (MVWB) is also found to be better than the traditional wafer bonding.

Qualitative description of the mechanism of MVWB is proposed in present work. It is believed that the medium vacuum can enhance the out-diffusion of the water molecules and other trapped impurities through the bonding interface which is porous initially. This enhanced diffusion speeds up the chemical reaction for the formation of Si-O-Si, and thus more bonding sites are available before the interface close-up. As a result, we observe an increase in bonding strength, bonding efficiency and the bonding speed.

An initial study of the RF hollow cathode plasma jet deposition of BaxSr1-xTiO3 has been performed. Deposition occurred from a single composite nozzle consisting of BaTiO3 and SrTiO3 at substrate temperatures on the 500-550 C range. It has been shown that film composition can be easily controlled by the nozzle composition as well as other deposition parameters. The as-deposited films exhibit clear BSTO peaks with grain size on the order of 30nm.

Zinc oxide (ZnO) films were deposited on polyimide-based substrates by pulsed laser deposition. The ZnO films and the underlying polymer layers were studied using Fourier Transform Infrared (FTIR) and Photoluminescence (PL) spectroscopies. FTIR measurements in structurally well-characterized samples exhibiting all X-ray reflections of crystalline hexagonal ZnO show absorbance bands around 405 cm-1(Zn-O stretching vibration) and 1110 cm-1 (in-plane C-H vibrations on aromatic rings of polyimide). Observed shifts in both absorption features as a function of deposition temperatures can probably be attributed to thermal stress in the layers. PL measurements showed broad spectra centered around 3.35 eV from ZnO excitonic emission and a broader PL band from 2.7 to 3.1 eV defect complex emissions. The appearance of these peaks was consistent for depositions of ZnO on non-organic substrates, which indicates that the integration of ZnO thin films on polymer based substrate preserved the characteristic optical properties of ZnO.

Color information is commonly captured by silicon sensor arrays covered by a mosaic of color filters. However, the detection of the colors red, green and blue at different spatial positions of the sensor arrays leads to color aliasing or color moiré effects. This effect inherently limits conventional sensor arrays. In order to overcome this limitation we have realized color sensors based on vertically integrated thin-film structures. The complete color information can be detected at the same position of a sensor array without using optical filters. The sensors consist of a multilayer thin-film system based on amorphous silicon and its alloys. The spectral sensitivity of the sensors can be controlled by the optical and optoelectronic properties of the employed materials and the applied bias voltages. The working principle of the thin-film sensors and the sensor arrays will be presented. For the first time a large area three color sensor array was realized without using optical filters.

The aim of this work is to optimize the metal/silicon ratio on nickel metal induced crystallization of silicon. For this purpose amorphous silicon layers with 80, 125 and 220 nm thick were used on the top of which 0.5 nm of Ni was deposited and annealed during the required time to full crystallize the a-Si. The data show that the 80 nm a-Si layer reaches a crystalline fraction of 95.7% (as detected by spectroscopic ellipsometry) after annealed for only 2 hours. No significant structural improvement is detected by ellipsometry neither by XRD when annealing the films for longer times. However, on 125 nm thick samples, after annealing for 2 hours the crystalline fraction is only 59.7%, reaching a similar value to the one with 80 nm only after 5 hours, with a crystalline fraction of 92.2%. Here again no significant improvements were achieved by using longer annealing times. Finally, the 220 nm thick a-Si sample is completely crystallized only after 10 hours annealing. These data clear suggest that the crystallization of thicker a-Si layers requires thicker Ni films to be effective for short annealing times. A direct dependence of the crystallization time on the metal/silicon ratio was observed and estimated.

The structures that can be implemented and the materials that are used in complementary metal-oxide semiconductor (CMOS) integrated circuit (IC) technology are optimized for electronic performance. However, they are also suitable for manipulating and detecting optical signals. In this paper, we show that while CMOS scaling trends are motivated by improved electronic performance, they are also creating new opportunities for controlling and detecting optical signals at the nanometer scale. For example, in 90-nm CMOS technology the minimum feature size of metal interconnects reaches below 100 nm. This enables the design of nano-slits and nano-apertures that allow control of optical signals at sub-wavelength dimensions. The ability to engineer materials at the nanoscale even holds the promise of creating meta-materials with optical properties, which are unlike those found in the world around us. As an early example of the monolithic integration of electronics and sub-wavelength metal optics, we focus on integrated color pixels (ICPs), a novel color architecture for CMOS image sensors. Following the trend of increased integration in the field of CMOS image sensors, we recently integrated color-filtering capabilities inside image sensor pixels. Specifically, we demonstrated wavelength selectivity of sub-wavelength patterned metal layers in a 180-nm CMOS technology. To fulfill the promise of monolithic photonic integration and to design useful nanophotonic components, such as those employed in ICPs, we argue that analytical models capturing the underlying physical mechanisms of light-matter interaction are of utmost importance.

The miniaturization of electrochemical transducers is crucial for the development of implantable biosensors, wearable microdetectors, and remote sensing networks due to the small dimensions required in these applications. As sensors scale, the analytical response degrades and integrated instrumentation is required to maintain acceptable detection limits. This work details the development of CMOS-integrated liquid chemical sensors. The sensors were cost-effectively post-processed on top of foundry-fabricated CMOS electronics using thin-film techniques. CMOS-integrated voltammetric sensors demonstrated a 25x improvement in detection limit/electrode area versus passive sensors. CMOS-integrated, ion-selective electrodes demonstrated a 50x improvement in lifetime and a 200x improvement in response time versus passive sensors. With their improved performance, these smart sensors can be used in a wide range of applications and can additionally serve as enabling technologies for more complex, chip-scale systems.

Compatibility in cofiring low-κ and middle-κ based on a same glass composition for the hybrid LTCC material systems was investigated. Designing of appropriate lithium borosilicate glass frit systems allowed us to develop an optimized glass frit system used for low-κ and middle-κ dielectric fillers, commonly. The effects of glass addition on the densification and electrical properties in low-κ and middle-κ dielectric materials were also examined. Controlling glass compositions and contents we tried to match low-κ and middle-κ tapes physically and chemically.

Inductors are important components of analog circuit designs, from matching circuitry to passive filters. In this study, the application of electrophoretically deposited nano-ferrite material has been investigated as a technique to increase the inductance of integrated copper planar inductors fabricated using copper plating and chemical mechanical planarization. Sintered Mn-Zn ferrite particles are suspended in a medium of isopropyl alcohol with magnesium nitrate and lanthanum nitrate salts. The transportation of the particles to the substrate surface is assisted by applied electric field and particles adhere to the substrate surface by a glycerol based surfactant. Electrophorectic deposition process forms a self aligned polymeric thin film on the surface of a p-type silicon substrate selectively with respect to copper. This ferrite deposition method yields high selectivity to the inductor coils and patterned silicon substrates compatible with standard silicon technology.

The feasibility of micro total analysis systems (μTAS) on microchips based on the concept of a monolithic instrument is demonstrated. In such a device a microfluidic layer system is deposited in a backend process on a conventional CMOS integrated circuit with the aim to achieve cost and performance enhancements through integration and miniaturization. Experimental results on elementary functional components of a μTAS are presented including a narrow channel electroosmotic micropump, a micro mass flow meter using the thermal anemometric principle, a micro cytometer with integrated optical detection, and elementary structures for on-chip micro-capillary electrophoresis.

This work focuses on photonic crystals (PC) that can be ascribed an effective index of refraction > 1 or even > 0. We investigate the possibility to design optical elements (in this case a lens) based on this type of PC. A new approach for determining the effective refractive index of PCs with unusual index of refraction is used, which is simpler than earlier methods based on analyzing equi-frequency surfaces in k-space. An ultra-low refractive index PC is given a form approximating a concave lens and is proven theoretically and experimentally that it efficiently focuses the electromagnetic radiation in the microwave range. Strong focusing effects are found for both polarizations (TE and TM mode). Intensity gains as large as 35 for TM polarizations and 29 for TE polarizations are found. Measurements are in a good accordance with simulations.

Organic light emitting diodes (OLEDs) require a transparent conducting oxide (TCO) electrode for injection of charge carriers and the emitted light to come out. In order to exploit the full flexibility of organic semiconductor based large area electronic devices, the deposition of TCO on plastic substrates is essential, which prohibits high temperature processing. Therefore, low temperature deposition of Indium tin oxide (ITO) films is very important for flat panel displays and solar cells. Here we have carried out a systematic study of ITO deposition on plastic substrates using RF magnetron sputtering. For the optimization of structural, electrical and optical properties of ITO, various experiments such as X-ray diffractometer, transmission measurements, sheet resistance and AFM were employed. These properties were investigated as a function of substrate temperature, deposition time and RF power. From these experiments, we obtained a reasonably low sheet resistance (˜ 14;Ω / □) and high transmittance (˜75%) in the visible region on plastic substrates. We also observed that these films are not much affected by atmosphere and does not degrade with time. These ITO films deposited by RF magnetron sputtering on plastic substrates can be use as anode for flexible organic light emitting displays.

While a-Si:H based elevated photodiode arrays hold the promise of superior performance and lower cost CMOS-based image sensors relative to those based upon crystalline silicon photodiodes, the one area where a-Si:H based sensor performance has not been as good is in image lag. This problem is only exacerbated by Staebler Wronski Effect induced junction degradation. Image lag is caused by residual charge from photocurrents trapped within the junction once the light source is removed and can be measured for several seconds, even under continuous applied reverse bias. It is seen both in constant and variable bias pixel architectures. However, by carefully controlling a-Si:H junction bias conditions, it is possible to significantly reduce these transient photocurrents. This article will describe how the photocurrent decay time exponent can be reduce by almost an order of magnitude. Finally the physical causes behind image lag in a-Si:H based photodiode arrays will be discussed.

Thanks to its three-dimensional integration and the use of amorphous as well as crystalline silicon, the TFA technology is suitable for advanced image sensor applications. This paper describes the fundamentals of the properties: sensitivity, dark current, temporal and fixed-pattern noise of these TFA image sensors. It compares the different sensitivity definitions, especially current sensitivity and the charge conversion factor. Further, the dark current sources are pointed out, and their temperature behavior is described. By noise calculations, different pixel input stages are compared with regard to low light level detection.

A CMOS chip-based approach is reviewed for fully electronic DNA detection. The electrochemical sensor principle used, CMOS integration of the required transducer materials, chip architecture and circuit design issues are discussed, respectively. Electrochemical and biological results obtained on the basis of medium density microarray sensor CMOS chips with 16×8 sensor sites prove proper operation.

In this paper results of the deposition and annealing of hafnium oxide thin films are reported. Due to the sensor application in mind, thicknesses between 30 and 150 nm have been deposited by r.f. sputtering of a high purity oxide target. Annealing has an important influence on the layer structure, stress and application correlated properties. A detailed understanding of the layer preparation is necessary to adjust deposition and annealing. After deposition the layers are predominately amorphous, annealing leads to textured layers with monocline or orthorhombic phases.

Besides gas sensor applications optimized layers may serve as protective coating or combined with a second material to multi layer stacks as high reflective dielectric mirror.

A new class of silicon-based chemical and biological sensors that offer an electrical response to a variety of substances is described. The devices utilize silicon flow-through sensing membranes with deep trench structures formed to depths up to 100μm, fabricated by electrochemical etching which transforms the silicon into macro-porous silicon (MPS). The sensors have demonstrated the ability to detect the presence of certain chemical and biological materials. Although the principle of operation of the devices is fairly complex, the transduction mechanisms can be compared to chemiresistors and chemically sensitive field-effect transistors (chemFETs). The electrical responses that have shown the most sensitivity are AC conductance and capacitance. Previous work has demonstrated that upon exposure to organic solvents (i.e. ethanol, acetone, benzene) the devices exhibit a characteristic impedance signature. The devices have also shown the ability to detect the hybridization of complementary DNA. The incorporation of other materials that have demonstrated sensitivity to low ambient levels of contaminants is also under investigation. The sensors have been designed and fabricated in linear array configurations; a microfluidic transport chip/package co-design is currently in progress.

Electroluminescence (EL) emission controlled by means of surface acoustic waves (SAWs) in planar light-emitting diodes (pLEDs) is demonstrated. Interdigital transducers (IDTs) for SAW generation were integrated onto pLEDs fabricated following a scheme compatible with SAW propagation [1]. EL in presence of SAW was studied by time-correlated photon-counting techniques. We found intensity oscillation at the SAW frequency (˜1 GHz) demonstrating electron injection into the p-type region synchronous with the SAW wavefronts.

The result of GaAs growth on Si using a thin Ge buffer layer (about 0.5μm thick) is presented in this paper. A two-step method with a high temperature anneal between two steps is used to grow the Ge buffer layer. Single phase GaAs is grown on Ge by controlling the growth temperature, substrate miscut and the prelayers. No APD defect is observed by the XTEM and the threading dislocation density of GaAs grown using this method is about 5˜10×107cm-2. The PL intensity of GaAs is 10× less on Si substrate than on GaAs substrates.