[en] A silicon PIN photodiode is conventionally used to detect visible lights. And it can also detect radiations such as alpha particles, beta particles and low energy X-rays for the spectroscopic purpose. When a silicon PIN photodiode is matched with scintillators such as CsI(Tl), gamma-ray can be detected with relatively high efficiency. Silicon PIN photodiodes, which have different active areas (3 X 3 mm"2, 5 X 5 mm"2, 10 X 10 mm"2), are designed and fabricated with and without AR (Anti-Reflective) coating on the surface for gamma-ray detection. In this study, spectral responsibilities are compared with respect to the active areas and according to whether AR are coated. Electrical characteristics such as leakage currents and capacitances are also measured and compared. Silicon PIN Photodiodes were fabricated with AR coating or not. Leakage currents for all the PIN photodiodes show several nA up to 100 V. Spectral responsibility was also measured and compared to analyze AR coating effect. AR coated PIN photodiode detectors show higher sensitivity above 520 nm wavelength than normal-type. In next study, responsibility will be evaluated after matching with scintillator

[en] We proposed a method to reduce the operating voltage and the grey-to-grey switching time of a vertically aligned liquid crystal display using a mixture of planar and vertical polyimide alignment materials. The surface anchoring energy of the two-polyimide mixture was smaller than that of the pure vertical polyimide and consequently, liquid crystal molecules were easily switched to a planar state with an electric field, resulting in a greater maximum retardation than that of the pure polyimide at the same applied voltage. Rising time was also significantly reduced due to the suppressed optical bouncing effect in the mixed planar polyimide, and the decaying time showed negligible change. With the proposed approach, we can reduce the cell gap to obtain half-wave retardation allowing for faster response time while keeping a low operating voltage. (paper)