An analytical method of evaluating variation of the thresholdvoltage shift caused by the negative-bias temperature stress in poly-SiTFTs

The variation of the threshold voltage shift (V_th shift) caused by negative-bias temperature stress (-BT stress) in poly-crystalline silicon thin-film transistors (poly-Si TFTs) was investigated. Based on the chemical reaction caused by -BT stress at the poly-Si/SiO₂ interface and the poly-Si grain boundary, an analytical method of evaluating the variation of both the V_th shift and the initial V_th was proposed. It was shown from this analysis that the enlargement of the poly-Si grain, using Si₂ H₆ gas could be a solution for efficient reduction of the easily hydrogenated dangling bonds which resulted in the V_th shift and suppression of the V_th shift and its variation. Moreover, it was suggested that there are two kinds of the dangling bonds; one is hydrogenated by hydrogenation and can be dehydrogenated by -BT stress; the other is not hydrogenated and the variation of its density is much smaller than the former     

Peak noise removal by a facet model

A peak noise removal method based on local gray tone statistics from the facet model is introduced. Each pixel in an image is statistically tested to determine whether it belongs to the same gray tone intensity surface as its neighborhood pixels. If its gray tone is outside the 95 per cent confidence interval estimated from the neighborhood gray tones, it is judged as peak noise and its value is replaced by an average of the gray tone values of the neighborhood pixels. In order to estimate the local gray tone statistics, an assumption is made that the neighborhood region is described by a linear or quadratic facet surface model. It is also shown that this method can be successfully applied to scan line noise removal by using a one-dimensional (horizontal or vertical) neighborhood.     

Feasibility study on using imaging plates to estimate thermal neutron fluence in neutron-gamma mixed fields

In current radiotherapy, neutrons are produced in a photonuclear reaction when incident photon energy is higher than the threshold. In the present study, a method of discriminating the neutron component was investigated using an imaging plate (IP) in the neutron-gamma-ray mixed field. Two types of IP were used: a conventional IP for beta- and gamma rays, and an IP doped with Gd for detecting neutrons. IPs were irradiated in the mixed field, and the photo-stimulated luminescence (PSL) intensity of the thermal neutron component was discriminated using an expression proposed herein. The PSL intensity of the thermal neutron component was proportional to thermal neutron fluence. When additional irradiation of photons was added to constant neutron irradiation, the PSL intensity of the thermal neutron component was not affected. The uncertainty of PSL intensities was approximately 11.4 %. This method provides a simple and effective means of discriminating the neutron component in a mixed field.     

Superconductivity of FeSr2YCu2O6+δ

Resistivity measurements of polycrystalline FeSr₂YCu₂O_6+δ under magnetic fields up to 160 kOe were made to study the superconductivity of FeSr₂YCu₂O_6+δ in detail. The resistivity began to decrease at 64 K and dropped to zero at 38 K under zero magnetic field. The superconductivity in inter grain was affected by the magnetic field and zero resistivity was observed below 12 K under H=10 kOe. Above 20 kOe, the superconductivity in the grain began to be affected. Even with increasing magnetic field up to 160 kOe, zero resistivity was persisted below 10 K.     

Identification of stress-induced leakage current components and thecorresponding trap models in SiO2 films

Time-decay stress-induced leakage current (SILC) has been systematically investigated for the cases of both Fowler-Nordheim (FN) stress and substrate hot-hole stress. From the three viewpoints of the reproducibility of the-current component for the gate voltage scan, the change of oxide charge during the gate voltage scan, and the resistance of the current component to thermal annealing, it has been found that time-decay stress-induced leakage current is composed of five current components, regardless of stress type. Trap models corresponding to each current component have been proposed. In addition, it has also been proven that holes generate the electron traps related to one of those current components     

Drying Behavior of a Slip Cast Body Using a Microwave Heating

To reduce the drying period a significant enhancement of manufacturing speed and improvement of productivity of ceramic fabrication were needed. The evaporation and transport of water were the keys to drying and controlling the kinetics of drying, which subsequently affects the properties of green bodies. This research was conducted to investigate the effects of rapid drying of ZnO slip cast bodies by microwave drying and compared with those dried by conventional drying techniques. From these results, the extent of warpage of a dried body was smaller in microwave drying than in other conventional drying methods. Furthermore, the number and size of pores were smaller for this drying technique than for other drying methods after sintering. Microwave heating was tentatively considered as a small difference in the water content between the inside and the outside of the green body, because the free and bound waters with NH₄⁺ salt of polyacrylic acid in a green body were selectively heated compared with ZnO powder, and evaporation and diffusion of water was done efficiently from the inside of the green body under microwave drying. Microwave drying has merits in terms of both the rapid drying and structural uniformity of dried bodies. It not only reduces drying period, but also improves the characteristics of green and sintered bodies.     

Electroluminescence from surface layer of insulating polymer underac voltage application

Electroluminescence from a surface layer of polytetrafluoroethylene (PTFE) has been investigated using a photomultiplier tube and an intensified charge-coupled device (ICCD) camera under ac or half rectified ac (HRAC) electric fields tangential to the polymer surface. The electroluminescence (EL) characteristics from the polymer surface layer showed a similarity to those from PTFE and other polymer films subjected to ac or HRAC electric fields in the normal direction to the surface. ICCD imaging of EL indicated a large area of EL activity where the EL intensity was maximum at the electrode edge and EL was still observable 2 mm from the electrode. The injection and transport of electrons and holes via surface states in the surface layer and the subsequent electron-hole recombination give rise to EL, strongly depending on the spatial distribution of the surface states. The injection length of charges can be estimated to be at least 2 mm from the electrode in the tangential direction to the surface