Masayuki Nakamoto

Highly Integrated Field Emitter Arrays Fabricated by Transfer Mold Technique

Highly integrated field emitter arrays (FEAs) have been fabricated by the transfer mold technique to obtain highly uniform and stable field emission for highly efficient and reliable vacuum microelectronic devices. Transfer mold Mo FEAs containing 9,400,000 emitter tips with high emitter density of 7,840,000 tips/cm2 have demonstrated a low value of less than 0.7%. Highly uniform, and flickerless fluorescence has been observed in the entire area of the fluorescent screen corresponding to the FEAs. The principle of the vacuum microelectronic switching devices has been proposed and experimentally verified by applying a high anode voltage of ±1 kV, which will be capable of decreasing the size and the electric power loss of the high voltage electric power converters using conventional semiconductor devices such as light-triggered thyristors (LTT) and gate turn off thyristors (GTO) to less than 1/100 and 1/10, respectively.

Pyroelectric Infrared Sensor Using Modified Lead Titanate Ceramics

Pyroelectric properties of (Pb, Ca) [(Co1/2W1/2)]TiO3 ceramics have been studied by changing the Ca concentration. With an increase in Ca concentration, the pyroelectric coefficient P and figure of merit Fv increased and reached 4.43×10-8 C cm-20C-1, and 0.61×10-10 C cmJ-1, respectively. Pyroelectric characteristics have been improved to twice the values for the PbTiO3 ceramics. The maximum responsivity Rv value versus chopping frequency is obtained in a less than 1 Hz frequency range. Responsivity Rv and specific detectivity D* are 780 V/W, and 1.1×108 cm √Hz/W at 1 Hz, respectively. The sensor is applicable for use as a human body sensor.

Photoisomerization of Azobenzene Dendrimer Monolayer Investigated by Maxwell Displacement Current Technique

Photoisomerization in monolayers of a novel azobenzene compound, azobenzene dendrimer, was investigated for the first time by means of the absorption spectrum and Maxwell displacement current (MDC) technique. According to the absorption spectrum, trans-to-cis conversion ratio was estimated to be approximately 10% for the third generation of azobenzene dendrimer deposited onto a glass substrate. Temperature-dependent induced charge with trans-cis isomerization was also measured by means of MDC technique, and we found that the thermal isomerization process must be taken into account for theoretical analysis of trans-to-cis photoisomerization. The temperature dependence was theoretically treated in terms of the three-state model that takes into account the stimulated thermal isomerization. As a result, we could obtain a ground state energy barrier of 0.93 eV in cis-to-trans isomerization for the first-generation of the azobenzene dendrimer (AZ-G1), and the value is in good agreement with the previous results obtained from the molecular orbital (MO) calculation which suggests that thermal cis-to-trans isomerization in AZ-G1 passes through the inversion process.