A successful cancer treatment is a combination of early diagnosis and efficient use of anticancer drugs. There is a chance of approximately 70 - 90% of cancer patients surviving if the diagnosis is conducted early. That means if a diagnosis system is in place which can detect multiple types of cancer at an early stage, a potential cancer therapy is most likely to succeed. However, at present, the available biomedical sensors are unable to detect and differentiate between cancerous cells or tumours. They are also not able to provide continuous real-time monitoring of a patient. Additionally, oral anticancer drugs given during chemotherapy, at the moment, suffer from low bioavailability. Also, a variety of these drugs is not targeted in nature. That means the drug will potentially affect areas of the body which do not need it. The low bioavailability of the drug will not only increase the chemotherapy sessions but also makes the entire process more aggravating for the cancer patient. Therefore, there is an absolute need to have innovative and efficient anticancer drug delivery mechanisms. Finally, current biomedical sensors are primarily made up of silicon (Si) or hard substrates based materials. Even if the biomedical sensor is of a flexible material, the material is either a fragile film or flexible but not stretchable polymers such as polyimide (PI). By having a biomedical sensor which is moderately flexible or not flexible at all, a continuous on-body biomedical sensing is not possible in an efficient manner. That is because hard substrates based biomedical sensors would be difficult to be placed on a body at all times. Furthermore, the flexible biomedical sensors currently suffer from problems such as the electrode on top cracking and damaging after few uses rendering them unusable. Hence, a new fabrication process needs to be devised to solve the issues mentioned above. In this work, an attempt is made to utilise zinc oxide (ZnO) nanostructures for biomedical sensing, drug delivery and biomimetics. ZnO nanostructures are synthesised by using a low-cost wet chemistry process known as hydrothermal growth. Due to the inherent biocompatibility and unique electrical/ piezoelectric properties of ZnO, they acted as prime candidates for the applications outlined above. A high-throughput process is used to synthesise ZnO nanowires (NWs) on Si, polyimide-onsilicon (PI/Si) and directly on PI and polydimethylsiloxane (PDMS) substrates. The work utilises a variety of characterization tools. ZnO nanostructures' morphology is characterised by using a Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and Atomic Force Microscope (AFM). X-ray diffraction (XRD) was used to calculate the crystallite size and the crystalline orientation of the nanostructures. A novel fabrication process is developed to allow direct synthesis and direct patterning of metal electrodes on fully flexible, stretchable and bendable PDMS substrates by using standard photolithography. This novel fabrication process makes the PDMS substrates not expand when exposed to temperatures up to 110 °C. Also; the new fabrication process does not cause the PDMS to swell when exposed to various chemicals such as isopropyl alcohol (IPA) or acetone. The fabrication process has created a new paradigm shift in the field of patterning and producing devices directly on flexible and stretchable substrates. The PDMS substrate is further utilised as a sensitive bovine serum albumin (BSA) protein sensor which is capable of detecting up to femtomolar concentrations in just under 5 min of incubation time. Protein biosensing tests were carried out by measuring the change in resistance at 1V bias voltage. The PDMS based biosensor is tested as a protein sensor because proteins are important biomarkers in cancer diagnosis. Also, protein sensors are immensely useful in the detection of bacteria and viruses thereby allowing further expansion to the technology developed herewith. For the first time, ZnO NWs are used to deliver hydrophobic organic dye, Nile red, in a human body like environment. The Nile red simulates an anticancer drug as they share similar surface chemistry. There is an approximately 80% release of Nile red which shows that ZnO NWs can be used as an efficient anticancer drug delivery system with high bioavailability. For the drug delivery experiments, the dynamic dialysis based release of Nile red (Nr) from the ZnO nanowires is carried out by using UV-Visible (UV-Vis) spectroscopy. Fourier Transform Infrared (FTIR) was used to determine the coordination of Nr across the ZnO nanowires. Finally, a novel synthesis process is used to produce individual ZnO NWs on a single ZnO nanoplate (NP) which are named as ZNWNP nanostructures. ZNWNP nanostructures have high hydrophobicity without the need of any functionalization. The hydrophobicity of the hybrid ZnO nanowires on ZnO nanoplate nanostructures (ZNWNP) is characterised by using contact angle goniometry (CAG). Various contact angle theories have been used to calculate the surface free energy (SFE) of the ZNWNP nanostructures. The high hydrophobicity allows these nanostructures to be used for biomimetic applications such self-cleaning, bioinspired sensors and multimodal biosensing. Additionally, ZNWNP nanostructures can be used in biomedical sensors to create multimodal analysis. The multimodal analysis is immensely useful in cancer detection as at least three or more cancer biomarkers can be used to triangulate the diagnosis. The work presented in the thesis aims to utilise ZnO nanostructures for a variety of biomedical applications. The new fabrication process mentioned above has applications not only in biomedicine but also in the flexible electronics industry. The biomimetic nanostructures combined with the biomedical sensor gives rise to a robust multimodal analysis system which can change the course of the cancer diagnosis. That coupled with the usage of ZnO NWs as an effective anticancer drug delivery system gives an immense promise in advancing cancer therapy as a whole and making the entire treatment process less aggravating and less painful for cancer patients.

L'objectif de cette étude consiste à synthétiser et caractériser de nouveaux matériaux hybrides organique/inorganique obtenus par greffage de poly(méthacrylate)s d'alkyle sur des nanoparticules de dioxyde de titane (TiO2) et d'oxyde de zinc (ZnO). Afin de mieux comprendre les facteurs influents les réactions mises en jeu lors d'un greffage à partir de la surface d'un oxyde métallique, nous avons choisi de travailler avec des nanoparticules disponibles commercialement et/ou élaborées. Des nanoparticules d'oxyde de zinc, de dimensions allant de 5 à 100 nm, ont été synthétisées par la méthode de précipitation, à température ambiante. La diffractométrie de rayons X (DRX) et la microscopique électronique à transmission (MET) ont permis de déterminer la structure cristalline, les dimensions et la morphologie des particules ainsi préparées. Les conditions de synthèse ont été optimisées afin d'augmenter la surface spécifique des particules tout en favorisant la présence de groupes hydroxyles en surface. La méthode de greffage de polymères méthacryliques a consisté à modifier préalablement la surface des nanoparticules par un agent de couplage réactif de type 3-méthacryloxypropyltriméthoxysilane (MPS). Les nanoparticules ainsi modifiées ont été caractérisées par spectroscopie (IRTF et RMN CP-MAS 13C et 29Si) et par analyse thermogravimétrique afin de confirmer la présence et la quantité de MPS greffé. Cet alcoxysilane, porteur d'une fonction méthacrylate, a permis de greffer des chaînes de poly(méthacrylate de méthyle), de poly(méthacrylate de tert-butyldiméthylsilyle) à partir de la surface des nanoparticules. La polymérisation radicalaire contrôlée par addition-fragmentation réversible (procédé RAFT) a été sélectionnée pour obtenir un contrôle des masses molaires, de faibles indices de polymolécularité et le greffage de copolymères diblocs. L'observation de ces nanoparticules hydrides en microscopie électronique à transmission montre clairement la présence d'une couronne de polymères à la surface des particules. L'étude de la stabilité thermique des nouvelles nanoparticules hybrides à base de ZnO a été réalisée par analyse thermogravimétrique sous atmosphère inerte. L'impact du procédé de polymérisation sur les mécanismes de dégradation thermique des polymères méthacryliques étudiés a été mis en évidence. Pour la première fois, des valeurs d'énergie d'activation ont été calculées sous atmosphère inerte et oxydante.

The aim of this thesis work was to fabricate a hybrid LED using organic-inorganic ZnO materials. The goal of the project was to get an efficient white light emission from zinc oxide (ZnO) nanorods active layer. Since most of the organic materials are good for hole mobility and most of the inorganic materials are good for electron mobility, it is possible to fabricate a high performance heterostructure electroluminescence device from organic-inorganic materials. This thesis work was an attempt towards fabricating such a high electroluminescence LED from hybrid materials in which polymer acts as a p-type material and ZnO acts as a n-type material. The growth mechanism of ZnO nanorods using low-temperature aqueous solution method has been studied and nanorods (NRs) growth was examined with scanning electron microscope (SEM). Optimum hole injection polymers have been studied. Finally, the fabricated device was characterized using parameter analyzer. The fabricated device worked as a diode i.e. it rectified current as expected and the desirable light emission has almost been achieved.

The structural quality of material (concentration and nature of defects) and optical properties (intensity and spectral emission range) of semiconductor materials are usually closely correlated. The idea of this work was to carry out a basic characterization of the structural (by X-ray diffraction technique and scanning electron microscopy) and optical (by micro photoluminescence measurements) properties of nanocrystalline ZnO samples and find a correlation. A number of ZnO samples prepared by atmospheric pressure metalorganic chemical vapor deposition at different regimes and on different substrates were investigated. According to the aim of the work the most important results can be summarized as following. The analysis of ZnO nanocrystalline structures deposited on Si (100) substrates have displayed a dependence of structural quality, morphology and microstructure as well as the optical spectral purity on the deposition temperature. The deposition at 500 ºС resulted in the massive of 1D ZnO nanopillars that demonstrated the best optical properties: a mono-emission in the ultraviolet spectral range was observed. Moreover, the results of microstructure investigation give a suggestion to the explanation of the ZnO nanopillars growth. The results obtained from ZnO on sapphire substrates revealed a moderate influence of the oxygen content during deposition on the structural quality of zinc oxide. However, a strong correlation between the oxygen content and deep-level emission intensity from ZnO nanostructures has been observed, which confirms the determinative role of oxygen for the defect emission from ZnO. It was shown that during the deposition of ZnO on specially prepared homoepitaxial template the substrate surface has not the major effect on the morphology of depositing ZnO structures. SiC was revealed to be the most appropriate substrate for hetero-deposition of textured ZnO nanostructures: the growth results in the massive of epitaxially related ZnO hexagons on the SiC (0001) plane. A number of factors - p-type conductivity of the substrate used, regular and uniform epitaxial growth of ZnO nanostructure, their excellent mono-spectral emission in short wavelength range of spectra, provides a strong background for further investigation of the electroluminescence properties of the obtained heterostructures and are of great importance for the progress of optoelectronics towards low-scaled elements.

The understanding of surfaces of materials is of crucial importance to all of us. Considering nanocrystals (NCs), that have a large surface to bulk ratio, the surfaces become even more important. Therefore, it is important to understand the fundamental surface properties in order to use NCs efficiently in applications. In the work reported in this thesis ZnO NCs were studied. At MAX-lab in Lund, synchrotron radiation based Spectroscopic Photoemission and Low Energy Electron Microscopy (SPELEEM) and X-ray Photoelectron Spectroscopy (XPS) were used. At Karlstad University characterization was done using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), Scanning Tunnelling Microscopy (STM), Auger Electron Spectroscopy (AES), and XPS. The fundamental properties of ZnO surfaces were studied using distributions of ZnO NCs on SiO2/Si surfaces. The conditions for distribution of ZnO NCs were determined to be beneficial when using ethanol as the solvent for ultrasonically treated dispersions. Annealing at 650 °C in UHV cleaned the surfaces of the ZnO NCs enough for sharp LEEM imaging and chemical characterization while no sign of de-composition was found. A flat energy band structure for the ZnO/SiO2/Si system was proposed after 650 °C. Increasing the annealing temperature to 700 °C causes a de-composition of the ZnO that induce a downward band bending on the surfaces of ZnO NCs. Flat ZnO NCs with predominantly polar surfaces were grown using a rapid microwave assisted process. Tuning the chemistry in the growth solution the growth was restricted to only plate-shaped crystals, i.e. a very uniform growth. The surfaces of the NCs were characterized using AFM, revealing a triangular reconstruction of the ZnO(0001) surface not seen without surface treatment at ambient conditions before. Following cycles of sputtering and annealing in UHV, we observe by STM a surface reconstruction interpreted as 2x2 with 1/4 missing Zn atoms. / Baksidestext The understanding of the surfaces of materials is of crucial importance to all of us. Considering nanocrystals (NCs), that have a large surface to bulk ratio, the surfaces become even more important. In the work in this thesis ZnO NCs were studied. The fundamental properties of ZnO surfaces were studied using distributions of ZnO NCs on SiO2/Si surfaces. Annealing at 650 °C in UHV cleaned the surfaces of the ZnO NCs enough for sharp LEEM imaging and chemical characterization while no sign of de-composition was found. A flat energy band structure for the ZnO/SiO2/Si system was proposed after 650 °C. Increasing the annealing temperature to 700 °C causes a de-composition of the ZnO that induce a downward band bending on the surfaces of ZnO NCs. Flat ZnO NCs with predominantly polar surfaces were grown using a microwave assisted process. Tuning the chemistry in the growth solution the growth was restricted to only plate-shaped crystals, i.e. a very uniform growth. The surfaces of the NCs were characterized using AFM, revealing a triangular reconstruction of the ZnO(0001) surface not seen without surface treatment at ambient conditions before. Following cycles of sputtering and annealing in UHV, we observe by STM a surface reconstruction interpreted as 2x2 with 1/4 missing Zn atoms.

Lighting is a big business, lighting consumes considerable amount of the electricity. These facts motivate for the search of new illumination technologies that are efficient. Semiconductor light emitting diodes (LEDs) have huge potential to replace the traditional primary incandescent lighting sources. They are two basic types of semiconductor LEDs being explored: inorganic and organic semiconductor light emitting diodes. While electroluminescence from p-n junctions was discovered more than a century ago, it is only from the 1960s that their development has accelerated as indicated by an exponential increase of their efficiency and light output, with a doubling occurring about every 36 months, in a similar way to Moore's law in electronics. These advances are generally attributed to the parallel development of semiconductor technologies, optics and material science. Organic light emitting diodes (OLEDs) have rapidly matured during the last 30 years driven by the possibility to create large area light-emitting diodes and displays. Another driving force to specifically use semiconducting polymers is the possibility to build the OLED on conventional flexible substrates via low-cost manufacturing techniques such as printing techniques, which open the way for large area productions. This thesis deals with the demonstration and investigation of heterojunction LEDs based on p-organic semiconductor and n-ZnO nanostructures. The ZnOorganic heterojunctions are fabricated using low cost and simple solution process without the need for sophisticated vacuum equipments. Both ZnO-nanostructures and the organic materials were grown on variety of substrates (i.e. silicon, glass and plastic substrates) using low temperature methods. The growth mechanism of the ZnO nanostructures has been systematically investigated with major focus in ZnO nanorods/nanowires. Different organic semiconductor materials and device configurations are explored starting with single polymer emissive layer ending up with separate emissive and blocking layers, or even blends. Interestingly, the photoluminescence and electroluminescence spectra of the hybrid LEDs provided a broad emission band covering entirely the visible spectrum [∼400-∼800nm]. The hybrid light emitting diode has a white emission attributed to ZnO intrinsic defects and impurities in combination with the electroluminescence from the conjugated polymers. The ZnO nanostructures in contact with a high workfunction electrode constitute an air stable electron injecting contact for the organic semiconductor. Hence, we have shown that a white light emission can be achieved in a ZnO-organic hybrid light emitting diode using cheap and low temperature growth techniques for both organic and inorganic materials. / The series number "1504" is incorrect and is changed in the electronic version to the correct number "1405".

Non-volatile memory is slower than DRAM (Dynamic Random Access Memory) but faster than HDD (Hard Disk Drive). In addition, compared to volatile memory, the non-volatile memory can retain stored information without power, and consume only low power. These characteristics show its popularity of flash memory built in portable devices. Currently the non-volatile memory applies the polysilicon and SONOS structure as floating gate, however, the new technologies of nanocrystal non-volatile memory are processed at high temperature. The manufacturing cost is rather high, so the process at lower temperature is very necessary. In this work, mixed zinc and silica amorphous layers are applied as floating gate to construct nano thin film non-volatile memory devices. The process does not need high temperature to form crystalline, and the defects in zinc oxide can be applied for charge storage. Supercritical carbon dioxide (SCCO2) treatment has been studied for the passivation of dielectric and reducing the activation energy. Using this low-temperature SCCD process ZnO nanocrystal can be formed, and the feasibility of fabricating nanocrystal NVMs device with low temperature SCCO2 is possible. The nonvolatile memory devices with Zn nano thin film embedded in MIS structure are performed. From C-V measurement, it is found that defects in SiO2 are repaired after 500¢J annealing. Because of the thermal diffusion, the storage layer SiO2/Zn-SiO2/SiO2 in device cannot be observed and the memory window disappears when the annealing temperature is higher than 700¢J. Therefore, the annealing process should be performed between 500¢J - 700¢J in making memory device. From DLTS analysis, a species with energy level of 0.6 eV is found in the as deposited Zn-SiO2 layer. After annealing in Ar, a new energy level 0.47 eV is found, and which shifts to energy level 0.85 eV after annealing in O2. In comparison to XPS results, traps of Zn-SiO2 exist before annealing, and after annealing in Ar, Zn-SiO2 transforms into Zn-O-Si. Traps of ZnO-SiO2 have been found after annealing in O2, which increases the memory effect with a 2 Volt memory window, so that more charges can be stored in the deep level traps of ZnO-SiO2 in the storage layer.

This investigation examines a novel means of integrating high-performance ZnO piezoelectric thin films with a flexible stainless steel substrate (SUS304) to fabricate a double-sided piezoelectric transducer. The double-sided piezoelectric transducer is constructed by depositing ZnO piezoelectric thin films on both the front and the back sides of SUS304 substrate. The titanium (Ti) and platinum (Pt) layers were deposited using a dual-gun DC sputtering system between the ZnO piezoelectric thin film and the back side of the SUS304 substrate. Scanning electron microscopy and X-ray diffraction of ZnO piezoelectric films reveal a rigid surface structure and highly c-axis-preferring orientation. To fabricate a transducer with a resonant frequency of about 80 Hz, a cantilever length of 1 cm and a vibration area of 1 cm2 are designed, based on the cantilever vibration theory. The maximum open circuit voltage of the power transducer is approximately 18 V. After rectification and filtering through a 33 nF capacitor, a specific power output of 1.3 £gW/cm2 is obtained from the transducers with a load resistance of 6 M£[.

Epitaxial m-plane (11 ¡Â00) ZnO thin films grown on m-sapphire substrates by atomic layer deposition have been studied. Atomic imaging and electron diffraction conducted in a transmission electron microscope (TEM) and crystallography by X-ray diffractometry all show consistent epitaxial relations with ZnO m-plane // sapphire m-plane, while ZnO [112 ¡Â0] // Al2O3 [0001], and ZnO [0001] // Al2O3 [112 ¡Â0]. The widths (full width at half maximum, or FWHM) of the rocking curves depend on the crystallographic axis of rotation. Dislocations near the interface between the ZnO epi-layers and sapphire substrates can be found from the cross-sectional TEM images when the direction of the incident electron beam, namely, the zone axis, is parallel to ZnO [112 ¡Â0], the a-axis of ZnO. There are stacking faults found in ZnO films away from their interfaces with the substrates. Polarization-dependent photoluminescence by differently polarized incident laser beam have also been investigated. Careful analysis of the spectra via multi-peak fittings revealed optical transitions at 3.32eV for T = 15K, which, however, shifted to 3.28eV at T = 300K. This shift in energy is accounted for by the quadratic temperature dependence of the Fermi level as determined by the positions of the lines of emission corresponding to the band edge transition. The 300K spectrum showed a more distinct peak at 2.48eV when the polarization of the emitted light was along the a-axis of ZnO, as compared to that along the c-axis of ZnO. The origin of this difference remains unaccounted for at the time of writing this thesis. The rest of the peaks have been interpreted in terms of optical transitions involving band gap impurity states, possible exciton formations, and their interactions with phonons.

A novel liquid sensor is designed and fabricated by using thin film bulk acoustic resonator (TFBAR) devices with c-axis 23¢X-tilted ZnO films. To fabricate TFBAR devices, the off-axis RF magnetron sputtering method for the growth of piezoelectric ZnO thin films is adopted. The influences of the relative distance and sputtering parameters are investigated. In this report, the piezoelectric ZnO thin films with tilting angle of 23¢X are set by controlling the deposition parameters. The properties of the c-axis 23¢X-tilted ZnO thin films are investigated by X-ray diffraction and scanning electron microscopy. The frequency response is measured using an HP8720 network analyzer with a CASCADE probe station. The TFBAR devices with 23¢X-tilted ZnO thin films display shear and longitudinal resonant modes at 752.75 MHz and 1.70 GHz, respectively. The mechanical quality factors (QL for longitude mode and QS for shear mode) are thus the important parameters of dual-mode TFBAR devices used in liquid environments. QL decreased from 545 to 0 upon in liquid loading, whereas QS remained almost unchanged at 296 in all environments. Moreover, the sensitivity of the shear mode to liquid loading is calculated to be 13 Hz cm2/£gg.