Moire/spl acute/ minimization condition in three-dimensional image displays

A moire/spl acute/ minimization condition is found analytically for the contact-type three-dimensional (3-D) imaging systems by approximating 3-D displays as four superposed sine gratings. Finding maximization conditions for two-dimensional (2-D) waves in this structure provides minimization of moire/spl acute/s. The global extremum was found at a certain angle which does not depend on the period. Experiments confirm the analytical findings. Practical advantage of using that angle is in its wide areas of applications: 3-D displays can be made to have almost invisible moire/spl acute/s with using this angle without regards to other specific parameters like pixel size and pitch of the screen.     

Sensitive strain measurements of bonded SOI films using Moire/spl acute/

The authors have developed a simple technique to quantify strain in bonded Si films and used it to compare the strain induced by two distinct wafer bonding methods. This method consists of patterning sets of moire/spl acute/ gratings on silicon-on-insulator (SOI) substrates prior to bonding using a G-line stepper. After planarization, bonding, and etch-back, the same lithography step is performed on the flipped patterns. The resultant interference between upper and lower gratings produces moire/spl acute/ fringes which is a measure of the strain. In the experiments, the sensitivity of the measurement is approximately 20 nm. This approach has been used to compare two methods of wafer bonding. The first method, a manual bonding technique, yielded strain of up to 100 nm/mm. The second method employed a commercial-grade bonder and resulted in film strains below 40 nm/mm. In the bonding schemes the authors have studied, they believe strain results mainly from induced wafer bow during bonding and stress contributions of deposited films. This scheme was developed to address wafer strain that arises from a direct-alignment double-gate MOSFET fabrication scheme (Meinhold, 1994).     

Ramped current stress for fast and reliable wafer level reliability monitoring of thin gate oxide reliability

A ramped dielectric stress measurement, suitable for fast wafer level reliability (fWLR) monitoring, is assessed for thin gate oxide thicknesses down to 2.2 nm. Severe difficulties usually occur for the reliable detection of soft/hard breakdown in a short time interval and due to high direct tunneling currents. These are discussed and an exponentially ramped current stress is introduced tackling the problems. Early oxide fails were covered by a fast voltage ramp carried out before the current ramp. The advantages of the method are highlighted which has already been implemented for fWLR monitoring in high volume production on scribe line structures.     

Electrooptic temperature sensor based on a Fabry-Pe/spl acute/rot resonator with a liquid crystal film

An electrooptic (EO) temperature sensor based on a Fabry-Pe/spl acute/rot (FP) resonator with a nematic liquid crystal (NLC) film is proposed. A novel compensation scheme of the EO effect allows for precise determination of temperature by monitoring the resonant wavelength of the NLC FP sensor. The proposed EO temperature sensor provides good stability, high resolution, self-calibration capability, and low driving voltage.     

A study on the variation of effective CTE of printed circuit boards through a validated comparison between strain gages and Moire/spl acute/ interferometry

The effective coefficient of thermal expansion (CTE) of printed circuit boards (PCBs) have a great deal of influence on the reliability of solder joints in microelectronic packages. In this paper we carryout a systematic characterization of nineteen circuit board samples using strain gages, further validated by moire/spl acute/ interferometry, to understand the impact of CTE variation on the reliability of solder joints. It is shown that the measured effective coefficient of thermal expansion varied in a wide range by as much as 5 PPM about the commonly used value of 17 PPM. This is shown to cause a significant reliability impact for a representative plastic ball grid array package assembly. The comparison between strain gage and moire/spl acute/ interferometry showed good overall correlation, but differed from each other by as much as 2.73 parts per million (PPM). The possible sources of error in each technique are identified and discussed.     

An assessment of change in stress due to cross-sectioning in moire/spl acute/ interferometric characterization of electronic packages

Cross-sectional moire/spl acute/ interferometry technique is a very commonly applied one for the characterization of electronic packages. While the technique is popular, its use has not been accompanied by rigorous evaluation of its measurement accuracy. Such an evaluation, necessary because the cross-sectioning destructively modifies the original geometry, is the goal of the current paper. In the present study, a five-layer specimen with intact axi-symmetry as well as one in which the symmetry is destroyed through cross-sectioning are chosen as the vehicles for developing an understanding of the effect of cross-sectioning. We present a rigorous validation of an analytical elasticity model of axi-symmetric package-like structures in which the model prediction is shown to be accurate to within 1% of experimental measurement. The validated analytical model is used to estimate a reduction in radial stress of approximately 40% due to the cross-sectioning of the circular specimens, while the radial strains were virtually unaffected by cross-sectioning. These results suggest that cross-sectional moire/spl acute/ interferometry is likely to yield accurate strains, but not stresses. Since damage under cyclic loading is a function of both stress and strain, the use of moire/spl acute/ interferometry for studying the evolution of strains in packages under cyclic loading is likely to be grossly in error.     

Deposition of GaN thin film on ZnO/Si by DIBD method

The GaNis a semiconductor material witha widefor-bidden band(Eg=3.36eV).It has many unique advan-tages such as high electron drift velocity,small dielectricconstant,goodthermal conduction et al.It is a favorablematerial for making electric devices with hi…     

Wide-temperature-range operation of 1.3-/spl mu/m beam expander-integrated laser diodes grown by in-plane thickness control MOVPE using a silicon shadow mask

A new fabrication method of high-quality thickness-tapered semiconductor waveguides is proposed based on controlling in-plane thickness during MOVPE by using a comb-shaped silicon shadow mask. It was used to fabricate a 1.3-/spl mu/m-wavelength narrow-beam (less than 13/spl deg/) InGaAsP-InP laser diode, which achieved high-power (over 20 mW) operation up to 85.     

Continuously tunable 1.55-/spl mu/m VCSEL implemented by precisely curved dielectric top DBR involving tailored stress

We present an optically pumped and continuously tunable 1.55-/spl mu/m vertical-cavity surface-emitting laser (VCSEL). The device shows 26-nm spectral tuning range, 400-/spl mu/W maximum output power, and 57-dBm side-mode suppression ratio. The VCSEL is implemented using a two-chip concept. The movable top mirror membrane is precisely designed to obtain a tailored air-gap length (L'=16 /spl mu/m) and a radius of curvature (ROC=4.5mm) in order to efficiently support the fundamental optical mode of the plane-concave resonator. It consists of a distributed Bragg reflector (DBR) with periodic, differently stressed silicon nitride and silicon dioxide multilayers implemented by plasma-enhanced chemical vapor deposition. The lower InP-based part, comprising the InP-InGaAsP bottom DBR and the active region, is grown monolithically using metal-organic vapor phase epitaxy.     

Fabrication of Au/PEDOT stacked electrodes for organic thin film transistors by imprinting technology

In this work, the Au/PEDOT stacked source/drain electrodes of OTFTs were fabricated by combining the micro-contact inking and reversal imprinting. The PEDOT was inked on the mold by the micro-contact process and the Au/PEDOT stacked layer was transferred on pentacene by imprinting technology. The threshold voltage, and on-off ratio, carrier mobility, and source/drain contact resistance of organic TFTs were all improved by the proposed process.     

Multiplexing of millimeter-wave signals for fiber-radio links by direct modulation of a two-mode locked Fabry-Pe/spl acute/rot laser

In this paper, we introduce generation of multiplexed signals on the millimeter-wave bands for fiber-radio systems where an optical millimeter-wave generator is based on a two-mode locked Fabry-Pe/spl acute/rot (FP) slave laser, whose injection current is directly modulated by a signal source. We qualitatively consider the distortion of the millimeter-wave signals from the FP slave laser. The distortion components on the millimeter-wave bands are induced from the simultaneous modulation of the locked modes and the nonlinear modulation response of the FP laser. Two-tone modulation of the locked FP laser is examined to evaluate the dynamic range of the millimeter-wave signals against the second- and third-order distortion components. We also perform fiber transmission of three 156-Mb/s-BPSK signals on the 60-GHz band to demonstrate fiber-radio down-link systems. The total capacity of the down-link system is discussed. In addition, two methods for multicarrier generation on the millimeter-wave bands are proposed. Multicarrier generators supported by these methods can be used as local signals for up-link millimeter-wave signals. The first method is based on multitone modulation of the FP slave laser. We attempt the down-conversion of a 52-Mb/s ASK signal on the 60-GHz band by using the millimeter-wave local signals. The second method depends on the distorted modulation of the FP slave laser by using a single continuous wave signal where the DC-bias level of the FP laser's injection current is partly under the threshold value. We confirm that five carriers on the 60-GHz band are effectively generated by using the second method. Furthermore, the influences of the chromatic dispersion effects on the millimeter-wave local signals are investigated for both methods.     

Mobility enhancement by using silk fibroin in F16CuPc organic thin film transistors

High performance n-type F₁₆CuPc organic thin-film transistors (OTFTs) were fabricated on polyethylene terephthalate (PET) using silk fibroin as the gate dielectric. The average field-effect mobility (μ_FE) value in the saturation regime is 0.39 cm² V⁻¹ s⁻¹ approximately one order of magnitude higher than the reported values in the literature. A typical F₁₆CuPc OTFT exhibits an on/off current ratio of 9.3 × 10², a low threshold voltage of 0.65 V, and a subthreshold swing value of 730 mV/decade. The enhancement of μ_FE results from very good crystal quality of F₁₆CuPc on silk fibroin, supported by grazing incidence X-ray diffraction (GIXD) data.     

Fabrication of ridge waveguides in LiNbO3 thin film crystal by proton-exchange accelerated etching

A simple fabrication method of adhered LiNbO₃ ridge waveguides by accelerated etching of the proton-exchanged region is proposed and demonstrated. The waveguides were fabricated and tested at 1.55 mum wavelength. Strongly confined guided modes were obtained. The waveguides are suitable for efficient nonlinear-optic wavelength conversion devices.     

High performance of pentacene organic thin film transistors by doping of iodine on source/drain regions

Contact doping was conducted by iodine in a top contact configuration in a pentacene organic thin film transistor (OTFT), to investigate its effects on contact resistance and the resulting electrical performance. Iodine doping in the pentacene film caused the change of pentacene structure, thus leading to an increase in electrical anisotropy, i.e. ratio of lateral to vertical resistivity. The two resistive components of doped pentacene film underneath the Au contacts were major contributors to the contact resistance, and a model to explain the dependence of contact resistance on iodine doping was presented. Finally, OTFTs fabricated on iodine doped source/drain contacts exhibited high mobility of 1.078 cm²/V s, two times that of OTFTs with undoped contacts, due to the low contact resistance.     

Increasing the thin film inductance by using soft magnetic Co92Zr8 as conductor

Planar-type thin-film inductor has been fabricated using Co₉₂Zr₈ soft magnetic thin film with high permeability as conductor. The inductance of the Co₉₂Zr₈ inductor is about five times more than that of the Cu inductor at frequency 60 MHz. At the same time, the dissipation of thin-film inductor using Co₉₂Zr₈ is similar with that of the Cu inductor. This result presents a novel method for increasing the inductance of thin-film inductor with simple technical process.     

High quality SiO2/Si interfaces of poly-crystallinesilicon thin film transistors by annealing in wet atmosphere

A new post-metallization annealing technique was developed to improve the quality of metal-oxide-semiconductor (MOS) devices using SiO ₂ films formed by a parallel-plate remote plasma chemical vapor deposition as gate insulators. The quality of the interface between SiO₂ and crystalline Si was investigated by capacitance-voltage (C-V) measurements. An H₂O vapor annealing at 270°C for 30 min efficiently decreased the interface trap density to 2.0×10¹⁰ cm^-2 eV^-1, and the effective oxide charge density from 1×10 ¹² to 5×10⁹ cm^-2. This annealing process was also applied to the fabrication of Al-gate polycrystalline silicon thin film transistors (poly-Si TFT's) at 270°C. In p-channel poly-Si TFT's, the carrier mobility increased from 60-400 cm² V^-1 s^-1 and the threshold voltage decreased from -5.5 to -1.7 V     

Preparation and characteristics of the wide gap semiconductor Mg0.18Zn0.82O thin film by L-MBE

The high purity ZnO ceramic target and the (MgO)_0.1(ZnO)_0.9 target were fabricated. The wurtzite-phase ZnO thin film and ternary Mg_xZn_1−xO thin film were grown on sapphire (0001) substrates by laser molecular beam epitaxy (L-MBE) from the sintered ceramic targets separately. The films' transmittance spectra at room temperature for the ZnO film and the Mg_xZn_1−xO film were measured and compared while their room temperature photoluminescence spectra were done. The band-gap modulation is realized from 3.31 eV for the ZnO film to 3.64 eV for the Mg_xZn_1−xO alloy film. The Mg content x in the Mg_xZn_1−xO alloy film was determined to be 0.18.     

Mapping of sp2/sp3 in DLC thin film by signal processed ESI series energy-loss image

A set of signal processing methods comprising fast Fourier transform interpolation, maximum entropy deconvolution and wavelet transformation has been successfully integrated to improve the equality of the extracted C K-edge spectra from electron spectroscopic imaging (ESI) series. Fast Fourier transform interpolation is used to improve the dispersion arising from discrete sampling of ESI series in the energy space. The maximum entropy method is used to dispel the convolution effect resulting from that ESI series acquired with a finite energy window. Wavelet transformation is applied to de-noise the extracted ESI spectrum. The post-processed ESI spectrum has quality as good as that of a probe-acquired spectrum and makes semi-quantitative analysis of the two-dimensional sp2/sp3 ratio map in diamond-like carbon thin film possible. In general, this method is applicable for reconstructing good quality core-loss electron energy-loss spectra from a nanometre-sized area, so that it may be possible to quantitatively analyse two-dimensional information about electronic structure in materials with near nanometre resolution.     

Controllable nanostructures on La0.7Sr0.3MnO3 thin film surfaces formed by scanning tunneling microscopy

Nanoscale structuring on La_0.7Sr_0.3MnO₃ (LSMO) thin film surfaces has been performed by scanning tunneling microscopy (STM) under ambient conditions. From line etching experiments we found that the line-depth increases in a stepwise fashion with increasing bias voltage. It also increases with decreasing scan speed and increasing scan repetition. We observed that the line-depth is an integral multiple of the LSMO out-of-plane lattice constant about 0.4 nm. Lateral structure with minimum feature size of 1 nm is possible to obtain. In addition, a four-level inverse-pyramid structure has been created on LSMO thin film surfaces. Our work shows the feasibility of using STM to fabricate controllable and complex nanostructures in LSMO thin film.