Wire bond reliability testing typically consists of aging bonds in a high temperature environment for long time periods, and removing samples at intervals to assess bond shear strength and characterize the bond cross sections. In this way, the degradation of the bond can be monitored at discrete time intervals, and it is determined whether the bond will be reliable during the specific service life. This process can be labour and time intensive. An alternative method is reported using an existing test chip that allows for contact resistance measurements and provides signals from piezoresistive integrated CMOS microsensors located around test bond pads. The sensors are sensitive to radial compressive or tensile stresses occurring on the bond pad due to intermetallic formation, oxidation, and crack formation at the bond interface. Two sets of identical test chips are bonded with optimized Au ball bonds and aged for 2000 h at 175 ºC. One set is connected to equipment which monitors signals from the stress sensors and the contact resistance of the bonds. The other set is destructively tested by shear tests and cross sectioning. It is found that the stress sensors are capable of indicating which stage of bond aging is experienced by relating the signal to the relative density of the intermetallic compounds (IMCs) and oxide which form during aging. This research offers a valuable new method for accelerating bond process development. By using the sensors to determine the stage of aging experienced and the magnitude of changes happening to the bond, the initial bond quality and bond reliability can be roughly characterized. A useful application is in comparing large samples of bonds made under varying conditions, and determining relative reliabilities of the bonds. A small sample size is required, as the sensors allow for complete continuous aging histories of individual bonds, which was not previously possible. A new test chip is designed for use in future studies which allows for contact resistance measurement, and provides stress signals for up to 55 bonds. A multiplexer integrated on the chip allows for measurements from one specified bond pad at a time. The chip is also equipped with x and yforce measurements which can be used to monitor bond process, and a resistive temperature detector for temperature measurement. A miniaturized bond aging system is designed to facilitate future works where chips are subject to high temperature storage. A heating element fits over the cavity of a microelectronic package containing the test chip, and allows for precise temperature control, while using less power than a conventional oven, and maintaining a low temperature at electrical connections to the package.

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The quality of GaN template layer plays a very important role in high electron mobility transistors. We proposed a special method in the growth of molecular beam epitaxy to deal with the dilemma between structure and the morphology of GaN. In our study, we used a nitrogen-rich GaN growth condition to deposit the initial varied layer. After that, we changed the N/Ga ratio stepwise to the growth condition of gallium-rich GaN and grew the epitaxy layer right away. In X-ray diffraction analysis, the full width at half-maximum (FWHM) value of rocking curves of GaN(002) was improved relatively to gallium-rich sample from 531.69 arcsecond to 59.43 arcsecond. In atomic force microscopy (AFM) analysis, the root mean square (rms) roughness of sample surface was improved relatively to nitrogen-rich sample from 18.28 nm to 1.62 nm over 5 £gm ¡Ñ 5 £gm area. The Raman scattering shows there is a slightly tilted plane in gradient layer and the gradient layer can also slash the strain force which is caused from Ga-rich GaN epitaxy layer and AlN buffer layer. A series high mobility AlxGa1-xN/GaN heterostructures samples were grown on MOVPE-grown GaN templates substrate by molecular beam epitaxy with different Al concentrations (x = 0.017~0.355). The quality checked by XRD and AFM indicated that the excellent properties agreed with the GaN-template. The highest mobility in this series samples at 8 K is 19593 cm2/Vs with carrier concentration 3.13 ¡Ñ 1012 cm-2 and Al concentration x = 0.017. In our experiments, the carrier density decreases as Al concentration reduces. In the illuminated Hall measurement, there are only few electrons increased following blue LED illumination. It shows that there are only few deep level defects existing near the heterointerface. From temperature-depended Shubnikov-de Haas (SdH) oscillations, the electron effective mass m* in 2DEG are evaluated as 0.213 mo and for x = 0.207 0.227 moand 0.136 respectively. The high mobility AlxGa1-xN/GaN was fabricated to a series of wires by focused ion beam (FIB) equipment, and the width of the active channel is ranged from 900 nm to 50 nm (900 nm, 500 nm, 300 nm, 200 nm, 100 nm, 80 nm and 50 nm) with the channel orientation in [11 0] direction. The largest spin-splitting energy in the series of wires is 2.14 meV. Due to larger spin-splitting energy and quasi-ballistic transportation, the 200 nm wire is the best candidate to be the channel of the quantum-ring interferometer in our case.

The ruthenium dinuclear complexes with end-caping of pyridinedicarboxylate complexes of terpyridine (2,2':6',2'-terpyridine) and (tBu)3-terpyridine (4,4¡¦,4¡¦¡¦-tri-tert-butyl-2,2¡¦:6¡¦,2¡¦¡¦-terpyridine) bridging with carbon-rich alkynyl group are reported. These novel complexes are characterized by NMR, MALDI-MS, FT-IR, UV, and electrochemistry. In comparison with the system of tpy-Ru-tpy-(¡Ý)n-tpy-Ru-tpy, we found some interesting characteristics in the studies of electronic spectra and electrochemical measurements. Furthermore, one reversible and one irreversible electrochemical redox waves in positive wave were observed (E1/2 at 0.59 and 1.15 V (irrev.) for the complex with ethynyl spacer and E1/2 at 0.62 and 1.10 V (irrev.) for the complex with butynyl spacer), indicating a strong electronic interaction between two Ru metal centers. However, in the tpy-Ru-tpy-(¡Ý)n-tpy-Ru-tpy system, only one electrochemical redox wave at ~1.3 V was found. From the electronic and electrochemical analysis , the electronic interaction between two metal centers decreases as the number of alkynyl group increases.

Very recently, Rotello¡¦s research group synthesized nanoparticles bearing terpyridine (terpy) ligands and studied their self-assembly using a variety of transition metals. This paper describes a synthetic pathway to ferrocene- and biferrocene-functionalized terpyridine octanethiols, and the studies of self-organization of ferrocene- and biferrocene-functionalized terpyridine octanethiols chemisorbed on Au nanoparticles.

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In this thesis, we study the electrical characteristics of a series of polysilicon thin-film transistors (poly-Si TFTs) with different numbers of multiple channels of various widths, with lightly-doped drain (LDD) structures. Among all investigated TFTs, the nano-scale TFT with ten 67 nm-wide split channels (M10) has superior and more uniform electrical characteristics than other TFTs, such as a higher ON/OFF current ratio (>109), a steeper subthreshold slope (SS) of 137 mV/decade, an absence of drain-induced barrier lowering (DIBL) and a suppressed kink-effect. These results originate from the fact that the active channels of M10 TFT has best gate control due to its nano-wire channels were surrounded by tri-gate electrodes. Additionally, experimental results reveal that the electrical performance of proposed TFTs enhances with the number of channels from one to ten strips of multiple channels sequentially, yielding a profile from a single gate to tri-gate structure. In addition, we have also studied the multi-gate combining the pattern-dependent nickel (Ni) metal-induced lateral crystallization (Ni-MILC) polysilicon thin-film transistors (poly-Si TFTs) with ten nanowire channels. Experimental results reveal that applying ten nanowire channels improves the performance of Ni-MILC poly-Si TFT, which thus has a higher ON current, a lower leakage current and a lower threshold voltage (Vth) than single-channel TFTs. Furthermore, the experimental results reveal that combining the multi-gate structure and ten nanowire channels further enhances the entire performance of Ni-MILC TFTs, which thus have a low leakage current, a high ON/OFF ratio, a low Vth, a steep subthreshold swing (SS) and kink-free output characteristics. The multi-gate with ten nanowire channels NI-MILC TFTs has few poly-Si grain boundary defects, a low lateral electrical field and a gate channel shortening effect, all of which are associated with such high-performance characteristics. The PDMILC TFTs process is compatible with CMOS technology, and involves no extra mask. Such high performance PDMILC TFTs are thus promising for use in future high-performance poly-Si TFT applications, especially in AMLCD and 3D MOSFET stacked circuits. Otherwise, we have investigated the mechanism of the leakage currents in polysilicon TFT with different temperature and applied biases. Moreover, we have simulated the electric fields in different structure polysilicon TFT to explain the mechanism of the leakage currents. By comparing the leakage currents in different channel structures, the leakage current in nanowire channel structure is higher than that in non-nanowire channel structure. Moreover, the leakage current in multiple gate structure is lower than that in single gate structure. Therefore, these two experimental results are caused by high electric field in the drain-to-gate overlap and drain-to-body depletion region respectively.

The characteristics of liquid and solid aerosols have been intensively investigated by means of optical diagnostic techniques. Part I describes the characteristics of liquid aerosol formation formed by heat transfer fluids (HTFs) from bulk liquids. Part II investigates the characteristics of convective transport behavior of solid particles in virtual impactor (VI). The objective of part I is to establish correlations which offer predictions on atomized particle size of HTFs which are widely and commonly used in process industries. There are numerous reports stating that mist explosions formed from leakage cause disastrous accidents in process industries. For safety concerns, the characteristics of mist formation should be known in order to prevent HTFs from catching on fire or exploding. The empirical data on formation of mist are collected by the optical measurement technique, the Fraunhofer diffraction. The Buckingham-PI theorem is applied to establish a correlation between empirical data and representative physical properties of HTFs. Final results of correlations are solved by a statistical method of linear regression. The objective of part II is to investigate the characteristics of convective transport behavior in virtual impactor (VI) which is used to sort polydisperse precursor powder in the process industries of superconductor wire. VI is the device to separate polydisperse particles as a function of particle size by using the difference in inertia between different sizes of particles. To optimize VI performance, the characteristics of convective transport should be identified. This objective is achieved by visualization techniques. The applied visualization techniques are Mie-scattering and laser induced fluorescence (LIF). To investigate analytically, a local Stokes number is introduced in order to offer criteria on predicting the efficiency of VI performance and boundary effect on particle separation. The achieved results can enhance performance and eliminate defects by having knowledge of the behavior of solid particles in VI.

The present research presents procedures for exploitation of level sensitive latches in wire pipelining. The user gives a Steiner tree, having a signal source and set of destination or sinks, and the location in rectangular plane, capacitive load and required arrival time at each of the destinations. The user also defines a library of non-clocked (buffer) elements and clocked elements (flip-flop and latch), also known as synchronous elements. The first procedure performs concurrent repeater and synchronous element insertion in a bottom-up manner to find the minimum latency that may be achieved between the source and the destinations. The second procedure takes additional input (required latency) for each destination, derived from previous procedure, and finds the repeater and synchronous element assignments for all internal nodes of the Steiner tree, which minimize overall area used. These procedures utilize the latency and area advantages of latch based pipelining over flip-flop based pipelining. The second procedure suggests two methods to tackle the challenges that exist in a latch based design. The deferred delay padding technique is introduced, which removes the short path violations for latches with minimal extra cost.

The preparations of multinuclear supramolecules assembled from ethynylferrocene(s) redox-active subunit end-capping with [(£b5-C5H5)(dppe)Ru] metal centers are described. Electrochemical measurements indicate that ferrocenyl-ethynyl spacers appear to be promising spacers which can ensure fast and quantitative transfer of information between two Ru2+ metal centers.