[en] Cerium-doped gadolinium silicic dioxide crystal, GSO(Ce), is a high-Z non-hydroscopic scintillator that gives higher light yield than BGO, and can potentially replace NaI(Tl), CsI(Tl) and BGO in many applications. Its production cost, however, has been substantially higher than any of them, while its energy resolution has been worse than that of NaI(Tl) or CsI(Tl). The merit did not overcome these deficiencies except in limited applications. We developed a low background phoswich counter (the well-type phoswich counter) for the Hard X-ray Detector of the Astro-E project based on GSO scintillator. In the developmental work, we have succeeded in improving the light yield of GSO(Ce) by 40-50%. For energies above 500 keV, a large GSO(Ce) crystal (4.5 cmx4.5phi cm) now gives energy resolution comparable to or better than the best NaI(Tl) when read out with a phototube. With a small GSO(Ce) crystal (5x5x5 mm³) and a photodiode, an energy resolution comparable to or better than the best CsI(Tl) has been obtained. With this improved performance, we find that the much higher photopeak efficiency and the shorter scintillation decay time of GSO(Ce) offsets its higher cost for many applications. We summarize our past developmental work to decrease radioactive contamination and to increase light yield of GSO(Ce) for astronomical hard X-ray detection. Included also are measurements done after the unsuccessful launch of the Astro-E mission. The work is still continuing for the remake version of Astro-E Hard X-ray Detector

[en] The radiation hardness of prototype CsI(Tl) crystals has been tested for the barrel electromagnetic calorimeter for the BELLE detector of the KEK B factory. Although samples made by one of the producers were found to be soft under irradiation, the problem was quickly improved when this information was fed back. All the tested crystals were found to meet our requirement. The light output was found to be almost uniform along a crystal, even when the front part was damaged by radiation. The damage causes a degradation of the attenuation length due to the formation of color centers; this conclusion was confirmed by a Monte Carlo ray-tracing study. (orig.)

[en] Liquid crystal displays (LCDs) with Ga-doped ZnO (GZO) transparent electrodes on RGB color filters were fabricated to demonstrate the feasibility of using this new material as an alternative to indium tin oxide (ITO) electrodes. The process flow for fabricating LCDs with GZO electrodes was entirely compatible with that for commercially available LCDs using ITO electrodes. Concurrently, photolithography processing and wet-chemical etching techniques for the formation of GZO transparent electrodes on thin film transistor (TFT) arrays in LCD panels was developed. Fine-patterns of GZO with 2-μm line widths were successfully formed using lithography and wet-etching technology with a weakly acidic etchant of pH 5.5–6.8.

[en] The ferroelectric properties and piezoelectric properties of 5 μm thick Pb(Zr_xTi_1-x)O₃ (x = 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8) films with 20 μm diameter disk-shaped electrodes were studied. The ferroelectric properties and piezoelectric properties of the lead zirconate titanate (PZT) thick films were simultaneously measured with an atomic force microscope (AFM) connected to a ferroelectric test system. With regard of the ferroelectric properties, the coercive field Ec increases as the Zr content x decreases, and the remnant polarization Pr shows a peak at x = 0.6-0.7. These tendencies are consistent with bulk PZT. The piezoelectric constants, referred to as AFMd₃₃, show a maximum peak at x = 0.5 and a second peak at x = 0.7. This tendency is consistent with the simulation results for bulk PZT. The AFMd₃₃ peak at x = 0.5 corresponds to the morphotropic phase boundary and the AFMd₃₃ peak at x = 0.7 corresponds to the rhombohedral phase boundary between the high-temperature phase and the low-temperature phase. Observation results strongly suggest that the 5 μm thick films have the same ferroelectric and piezoelectric properties as those of bulk PZT