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The wide band gap (WBG) semiconductors such as Gallium Nitride (GaN) and Silicon Carbide (SiC) have characteristics of the low on-resistance and the high-speed switching for Si semiconductor. This paper proposes the Integrated Servomotor that integrates an AC motor with an amplifier miniaturized by adopting GaN power devices. Experimental results show the usefulness of GaN power devices in motor drive systems and the effect of the Integrated Servomotor on drive systems.

As market demand for energy conservation products are increasing, matrix converters need to be further improved in efficiency and downsizing. On the other hand, next generation power devices such as SiC, GaN, which are capable of high speed switching with low loss have recently gained attention. In particular, the bidirectional GaN device is constituted by connecting two devices in series on the same die, which has an advantage that the conduction loss and the mounting area can be reduced. Conventional matrix converter requires at least 18 devices, but if bi-directional GaN devices are used, they can be composed with only 9 devices, which is useful for high efficiency and downsizing by reducing the conduction loss of the matrix converter. Matrix converter chipset using bidirectional GaN devices has already been developed, but as far as the authors know, a three phase motor has not been driven. This paper introduces the prototype nine switches matrix converter using bi-directional GaN devices, which successfully drives a three phase motor.

The matrix converter is an AC-to-AC direct power conversion system that can generate variable voltage variable frequency output. There is a topology of Matrix converter having sinusoidal waveforms using output LC filter. It enabled that to provide lower EMI, lower common-mode current, and lower shaft voltage. However, there are some problems that filter size become bulky because of the restriction of switching speed using conventional power module, Silicon IGBT. Downsizing of input-output filter can be realized by employing SiC power devices since they are associated with low losses and can be operated at high frequency. In this paper, the use of SiC power devices in matrix converters is studied and its effect in reducing the size of the input and output filter is verified. A prototype was built for evaluations and the results are presented.

A beam test was executed to evaluate the behavior of the first prototype radiation-hard double-sided silicon microstrip sensor for the SDC silicon tracking system. Pions of 4 GeV/c in a test bcamline at KEK illuminated three planes of detectors. Thc signals wcrc amplified, shaped, and discriminated with TEKZ bipolar analog LSI's, and the on-off levels were sampled at l0MHz clock with CMOS digiwl LSI's, asynchronously with beam triggers. The detectors were rotated in null and 1 .O Tesla magnetic fields. The efficiencies were found to be 98-9996. The position resolutions were 12.5pm. where the multi-strip hit fraction was 30-40%. There was no essential difference in the performance of the pand the n-sides. The multi-strip hit fraction showed a clear rotation and magnetic-field dependence. From the angles where the fractions were minimum in the 1T magnetic field, the Hall mobilities of the electrons and holes were obtained to be 1391k43 (clcctrons) and 325f30 (holes) cm2/Vs.

A full-size, double-sided, AC coupling sensor for the SDC central tracker was fabricated. The bias feeding resistor for each strip on both surfaces was implemented by a poly-Si line. The resistance was well controlled within a design value which is good enough to feed uniform bias to each strip. The ohmic-contact strip isolation was attained by inserting a p/sup +/ channel between n/sup +/ strips. The readout capacitance was minimized by making a narrow strip on the p/sup +/ side and by inserting a wide isolation p/sup +/ channel in the n/sup +/ strip side. The capacitance is measured to be 0.8 pF/cm on the p/sup +/ strip side and 1.13 pF/cm on the n/sup +/ strip side. The junction edge breakdown voltage has been pushed up to more than 150 V by an Al strip narrower than the implanted strip width. >

The free ion yields from /sup 207/Bi conversion electrons were measured as a function of applied electric field using ionization chambers filled with tetramethylsilane (TMS) and tetramethylgermanium (TMG). The distributions for thermalization lengths of electrons were calculated by using Gaussian and exponential forms. The total free ion yields considering the impurity effect in liquid, and the thermalization lengths of electrons in TMS and TMG were determined to be 3.35+or-0.49, 3.42+or-0.56 and 165+or-18 AA, 185+or-24 AA, respectively. >

To test the radiation tolerance of full-size detectors, four large-area AC-coupled single-sided silicon microstrip detectors were fabricated. The detectors had a size of 6 cm/spl times/3.4 cm and were made out of a 300 /spl mu/m thick, high-resistivity, n-type silicon, simulating the p-side of the double-sided silicon microstrip detectors being developed. The AC coupling layer had either a single layer of SiO/sub 2/ or double layers of SiO/sub 2/ and Si/sub 3/N/sub 4/, in combination with the surface passivation of SiO/sub 2/ or Si/sub 3/N/sub 4/. The detectors were irradiated at room temperature by 500 MeV protons at TRIUMF to a fluence of 5.7/spl times/10/sup 13/ protons/cm/sup 2/, promptly stored at 0/spl deg/C after irradiation, and periodically measured over the following year. The full depletion voltages showed a substantial annealing and a gradual anti-annealing. The result was compared with the predictions of existing damage parameterization. Time variation of other characteristics, such as leakage current, interstrip and coupling capacitances, and strip-edge microdischarges was also followed. >

Superlattice type photodiodes of a GaAs-Al/sub x/Ga/sub 1-x/As structure were studied at room temperature. A combination of potential-well width and barrier width was sensitive to the charge multiplication factor. Using a diode with a 10 nm well and a 15 nm barrier, the detector characteristics were investigated from a point of view of achieving a high gain. This type of photodiode was confirmed to be sensitive to Cherenkov light generated in water. Effects of carrier doping up to 10/sup 18/ cm/sup -3/ at room temperature on the multiplication rate is discussed.

Acoustic detectors were developed using a piezo ceramic compound PZT. The shape of the PZT detector was essential to obtain a high sensitivity. A detector of a spherically shaped shell structure, whose size was 50 mm in diameter and 2 mm thick, was fabricated. Its sensitivity was calibrated to be about 40 mV/Pa at 54 kHz. Using the hydrophone, acoustic signals generated by an electron-induced cascade shower in water was detected. Experimental results were compared with simulation data and confirmed consistency.