In first part, the supercritical CO2 (SCCO2) fluid technology is employed to improve the device properties of ZnO TFT. The SCCO2 fluid exhibits liquid-like property, which has excellent transport ability. Furthermore, the SCCO2 fluid has gas-like and high-pressure properties to diffuse into the nanoscale structures without damage. Hence, the SCCO2 fluid can carry the H2O molecule effectively into the ZnO films at low temperature and passivate traps by H2O molecule at low temperature. The experimental results show that the on current, sub-threshold slope, and threshold voltage of the device were improved significantly. Next, the electrical degradation behaviors and mechanisms under drain bias stress of a-IGZO TFTs were investigated. A current crowding effect and an obvious capacitance-voltage stretch-out were observed after stress. During the drain-bias stress, the oxygen would be absorbed on the back channel near the drain region of IGZO film. Therefore, the carrier transport is impeded by the additional energy barrier near drain region induced by the adsorbed oxygen, which forms a depletion layer to generate the parasitism resistance. We also investigated the RRAM device based on IGZO film, and proposed the related physical mechanism models. The IGZO RRAM will be very promising for integration with IGZO TFTs for advanced system-on-panel display applications to be a transparent embedded system. In this part, the transparent RRAM device with ITO/IGZO/ITO structure was fabricated. The proposed device presents an excellent bipolar resistive switching characteristic and good reliability. The bipolar switching mechanism of our device is dominated by the formation and rupture of the oxygen vacancies in a conduction path. The influence of electrode material on resistance switching characteristic is investigated through Pt/IGZO/TiN and Ti/IGZO/TiN structure. As the bias applied on the Ti or TiN, the Ti or TiN electrode can play the role of oxygen reservoir to absorb/discharge oxygen ions. Therefore, the device presents a bipolar resistive switching characteristic. However, as the bias applied on the Pt electrode, the device presents a unipolar resistive switching characteristic. Because the Pt electrode can¡¦t store the oxygen ion, the device should use the joule heating mode to rupture the conduction path and present the unipolar resistive switching characteristic. Finally, the resistive switching properties of IGZO film deposited at different oxygen content were investigated, since the resistance switching behaviors are related to the formation and rupture of filaments composed of oxygen vacancies in the IGZO matrix. Experiment results show that the HRS current decreases when the oxygen partial pressure gradually increases. Based on the XPS analysis, these phenomena are related to the non-lattice oxygen concentration. With increasing oxygen ratio, the filaments will rupture completely through the abundant non-lattice oxygen inducing oxidation, which leads to HRS current decrease and an increase in the memory window.

We deposited CuInSe2 or CuIn1-xGaxSe2 on the substrate of bi-layer Mo by electrodeposition. Besides, we deposited bi-layer Mo by RF sputtering on soda-lime glass. First, we discussed the characteristic of Mo metal, and how can we have a good adhesion and a low resistivity simultaneously. Then, we deposited CuInSe2 and CuIn1-xGaxSe2 thin film by electrodeposition, and discussed the effect of depositing time, pH value in depositing solution, depositing current and different concentration ions respectively.

EDS is a tool for quantitative and qualitative analysis of the materials. In electron microscopy, the energy of the electrons determines the depth of the region where the X-rays come from. By varying the energy of the electrons, the depth of the region where the X-rays come from can be changed. If a thin film is used as a specimen, different quantitative ratios of the elements for different electron energies can be obtained. Unique thickness of a specific film on a specific substrate gives unique energy-ratio diagram so the thickness of a thin film can be calculated by analyzing the fingerprints of the energy-ratio diagram of the EDS data obtained from the film.

Since the traditional CRT(Cathode Ray Tube) replaced by FPD(Flat Panel Display), e.g. LCD¡BOLED¡BPDP, FPD industry is regarded as the important one of global industry following Semi-conductor industry. The main stream of Large-Area Displays is TFT-LCD(Thin Film Transistor-Liquid Crystal Display) and it¡¦s applied a-Si:H TFT (the hydrogenated Amorphous Silicon Thin Film Transistor) as pixel-switch device on LCD. In a-Si:H TFT Cell process, the active region material(a-Si:H) with higher Photoconductivity results into higher off-state current under light illumination and that causes color performance discrepancy as incomplete On/Off operation of pixel-switch devices. As long as the introduction of F into a-Si:H modify the density of states in the gap of a-Si:H(:F), that may result the shift of the Fermi level toward the valence band edge and The density-of-states increasing. It¡¦s effective to decrease the photo leakage current. Due to electro-optical properties of liquid crystal(LC), to drive Pixel-switch device in TFT-LCD shall force On/Off voltage to change Twist Angle of LC is corresponding to have Stress on TFT device. According to DC Stress experiment results, it¡¦s found TFT device with SiF4 dopant can reach better reliability. This issue is aimed to research the photo leakage current variation of a-Si:H TFT at low temperature and ON/Off state effect by stress on TFT device.

Previous studies on very high-cycle fatigue behavior of thin silicon films suggest a strong environmental dependence of the degradation mechanism, the precise nature of which is still subject to debate. In the present study, 2-micron-thick polycrystalline Si notched cantilever beam structures were used to investigate fatigue degradation in a high-temperature (80°C), high-humidity (90%RH) environment. The specimens were subjected to fully reversed sinusoidal loading at resonance (~40kHz) with stress amplitudes ranging from 1.46 to 1.6GPa, resulting in life-spans between 10⁶ and 10⁹ cycles. Comparison to a reference set of S-N data obtained at moderate environmental conditions (30°C and 50%RH) reveals a strong tendency for faster degradation with increasing temperature and humidity. The obtained damage accumulation rates in the 80°C, 90%RH environment exceed the reference by two orders of magnitude. Transmission electron microscopy (TEM) on vertical through-thickness slices reveals oxide thickening after cycling. The influence of ~20nm Al[subscript2]O₃ deposited on the surface of the fatigue specimens using Atomic Layer Deposition (ALD) technique was also studied. The presence of the alumina coating results in a higher fatigue resistance at 30°C and 50%RH, as well as a drastically different frequency evolution behavior. No oxide thickening was observed in the TEM for coated run-out specimens. A model is proposed to explain the different degradation behavior of the ALD-alumina coated samples. Thickened oxides after cycling appear consistent with the reaction-layer fatigue mechanism. Finite element modal analysis incorporating surface oxide layers and cracking was employed to relate the damage observed in TEM to the experimentally measured changes in resonant frequency. In conclusion, the reaction-layer mechanism seems capable of describing micron-scale polysilicon fatigue, even though the critical processes such as room-temperature, stress-assisted oxidation remain elusive.

The goal of the research in this dissertation is to develop techniques for 1) system-on-package integration of passive circuits using ultra-thin advanced polymers called RXP (Rogers experimental polymer), 2) extraction of frequency-dependent material properties up to millimeter-wave frequency, 3) development and synthesis of high-rejection filter topologies, 4) design and characterization of high performance miniaturized embedded passive circuits for microwave and millimeter-wave applications, and 5) development of via and through-silicon via (TSV) enhanced filter design method for integration in high-loss substrate. The RXP material is developed to reduce the layer-count for multi-layer configuration and adoption of advanced fabrication technologies. Frequency-dependent material properties of RXP, ceramic, and other materials have been extracted up to millimeter-wave frequency using parallel-plate resonator method. An automated extraction algorithm has been proposed to handle a large number of frequency samples efficiently. The accuracy of the extraction result has been improved by including the surface roughness effect for conductor operating at high frequency. Using extracted RXP material properties, 2.4/5 GHz WLAN bandpass filters have been designed and characterized. High-rejection bandpass filter topologies for narrow 2.4 GHz and wide 5 GHz have been proposed. The proposed topologies have been synthesized to provide design equations as well as graphical design methodologies using Z-parameters. A new capacitor design called 3D stitched capacitor has been proposed to achieve more symmetric layout by providing balanced shunt parasitics. The proposed topologies and design methodologies have been verified through the measurement of high-rejection RXP bandpass filters. Good correlation between the simulation and measurement was observed demonstrating an effective design methodology and embedding bandpass filters with good performance. Dual-band bandpass filters for WLAN applications have been implemented and measured. Instead of connecting two bandpass filter circuits, a new single bandpass filter topology has been developed with a compact size as well as high isolation between passbands. High-rejection duplexer has been designed in RXP substrate for chip-last embedded IC technology, and a novel matching circuit has been applied for the miniaturization as well. The 60 GHz V-band has special interest for wireless applications because of its high attenuation characteristics because of atmospheric oxygen. Millimeter-wave passive circuits such as bandpass filter, dual-band filter, and duplexer have been designed, and self-resonant frequency of passive components has been carefully avoided using the proposed method. For low-cost system integration, silicon interposer with through-silicon-via (TSV) technology has been studied. The filter design method for high-loss substrate has been proposed. The coupling characteristic of TSV has been investigated for obtaining good insertion loss in lossy substrates such as silicon, and TSV characteristics has been used to design bandpass and highpass filters. To demonstration of concept, bandpass filters with good insertion loss have been realized on high-loss FR4 substrate.

Hard ceramic films of micrometric thickness deposited on a soft metallic substrate have ushered in a new era in the fabrication of structural, tribological, microelectronic and optical components. The mechanical performance of these components is however critically dependent on the strength and toughness of these films as well as on those of the film-substrate interface. Recent studies have shown that cylindrical and radial cracks can propagate through the film during nanoindentation tests with spherically tipped and pointed indenters, resulting in steps in the load versus displacement curve. In this thesis, the mechanics of fracture of thin hard films bonded to soft substrates, during nanoindentation is studied by carrying out finite element analyses. The role of plastic yielding in the substrate on the above issue is examined. Another important objective of this work is to propose a method by which finite element simulations can be employed to interpret nanoindentation test results and yield information related to the fracture behaviour of hard films. To this end, axisymmetric finite element analyses of spherical nanoindentation of a TiN film of thickness t = 1 //m, on a steel substrate are carried out. Numerical algorithms for large deformation, contact simulation and computation of energy release rate are employed in the analyses. The film is assumed to be linear elastic, whereas, an elastic-plastic constitutive model is used for the substrate. A nanoindentation analysis of the uncracked film is first carried out. The development of plastic yielding in the substrate and its influence on the load P versus penetration h characteristics is examined. The stress fields around the indenter for different depths of indentation are studied. The results show that the radial stress attains a tensile peak at the film surface, just outside the indented zone. However, it becomes compressive with increasing distance below the surface. Interestingly, a tensile radial stress prevails at the film-substrate interface at large indentation depth. The shear stress increases to a peak value at a distance of 0.052 to OAt below the film surface depending upon the radial location and then reduces. Next, circumferential cracks extending downwards from the film surface are introduced at different radial distances R from the axis of symmetry. Finite element analyses are carried out till the indented zone extends almost up to the crack surface. The energy release rate J is computed as a function of indentation depth for different crack lengths c (in the range from O.lt to 0.9t). The results show that shallow cracks are essentially under Mode II loading with closure of crack faces caused by compressive radial stresses. However, a mixed-mode state prevails if the crack length is large (c > 0.62), with crack faces opening out due to tensile radial stress near the film-substrate interface. The variation of J with c/t for cracks located at different radial distances R is examined. It is found that for small R, there is a decreasing branch in the J versus c variation between c = 0.2i to 0.75£ which indicates that crack extension in this range will be stable. On the other hand, for large R, J increases monotonically with c/t which implies that unstable fracture of the full film thickness will occur following crack initiation. A composite nomogram is generated in the P — h plane where constant J lines are plotted along with load-displacement curves for different crack lengths. If now a nanoindentation (experimental) load-displacement behaviour is superimposed on this nomogram, the initial crack length (of a pre-existing flaw), the final crack length and fracture energy of the film can be inferred. In the last part of the thesis, the effect of the substrate yield strength on the indentation mechanics is studied. It is found that upon decreasing the yield strength, the load at a given indentation depth decreases while the residual depth at unloading increases. Also, the energy release rate for a given radial location and crack length reduces considerably at large depths of indentation.

Compared with its inorganic counterpart, organic thin-film transistor (OTFT) has advantages such as low-temperature fabrication, adaptability to large-area flexible substrate, and low cost. However, they usually need high operating voltage and thus are not suitable for portable applications. Although reducing their gate–dielectric thickness can lower the operating voltage, it increases their gate leakage. A better way is making use of high-κ gate dielectric, which is the main theme of this research. Firstly, pentacene OTFTs with HfO2 gate dielectric nitrided in N2O or NH3 at 200 oC were studied. The NH3-annealed OTFT displayed higher carrier mobility, larger on/off current ratio, smaller sub-threshold swing and smaller Hooge?s parameter than the N2O-annealed device. All these advantages were attributed to more nitrogen incorporation at the dielectric surface by the NH3 annealing which provided stronger passivation of surface traps. The incorporation of lanthanum to hafnium oxide was demonstrated to realize enhanced interface in the pentacene OTFTs. Therefore, pentacene OTFTs with HfLaO gate dielectric annealed in N2, NH3, O2 or NO at 400 oC were investigated. Among the 4 devices, the NH3-annealed OTFT obtained the highest carrier mobility, smallest sub-threshold swing and smallest 1/f noise. All these should be attributed to the improved interface between the gate dielectric and the organic semiconductor associated with the passivation effects of the NH3 annealing on the dielectric surface. The processing temperature of OTFTs is a big concern because use of flexible or glass substrate is the trend in organic electronics. Therefore, the HfLaO gate dielectric was annealed in N2, NH3, or O2 at two different temperatures, 200 oC and 400 oC. For all the annealing gases, the OTFTs annealed at 400 oC achieved higher carrier mobility, which could be supported by SEM image that pentacene tended to form larger grains (thus less carrier scattering) on HfLaO annealed at 400 oC. Furthermore, the HfLaO film annealed at 400 oC achieved much smaller leakage because more thermal energy at higher annealing temperature could remove oxide defects more effectively. Fluorination of the HfLaO film (annealed in N2 or NH3 at 400 oC) in a plasma based on CHF3 and O2 was also proposed. For both annealing gases, the OTFT with a 100-s plasma treatment achieved higher carrier mobility and smaller 1/f noise than that without plasma treatment. All these improvements should be due to fluorine incorporation at the dielectric surface which passivated the traps there. By contrast, for longer time (300 s or 900 s) of plasma treatment, the performance of the OTFTs deteriorated due to damage of dielectric surface induced by excessive plasma treatment. Lastly, a comparative study was done on pentacene OTFTs with HfLaO or La2O3 as gate dielectric. For the same annealing gas (H2, N2, NH3, or O2 at 400 oC), the OTFT with La2O3 gate dielectric obtained lower carrier mobility, smaller on/off current ratio, and larger threshold voltage than that based on HfLaO. The worse performance of the OTFTs with La2O3 gate dielectric was due to the degradation of La2O3 film caused by moisture absorption. / published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

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The research described covers fundamental studies of environmentally-responsive microgel-based thin films as a function of film architecture, microgel chemistry, film thickness, and environmental stimulus. Studies of multi-layer microgel thin films were conducted primarily using atomic force microscopy (AFM), quartz crystal microgravimetry (QCM), and surface plasmon resonance (SPR), each of which probed different aspects the film architecture as a function of pH of the environment around the film. Binary thin films were constructed by changing the ratios and composition of the microgels in solution to create multi-functional thin films for surface modification applications and were studied using AFM. The basic understanding of how these components create films at surfaces gives us insight into how the films perform and will allow for greater diversity without the guesswork. The morphology of films created from microgels with a degradable cross-linker was examined by AFM as a function of degradation of the particles structure. This thesis focuses mainly on very thin microgel films (<5 layers) studied using QCM, SPR, and AFM. Additional studies involving the characterization of semi-soft colloidal paint-on photonics are discussed in Appendix A.