Shoyu Watanabe

25.2: Fabrication of CNT Electron Source by Simple Stacking for Obtaining Uniform Emission Distributions

We have developed the technique of fabricating triode structure with simple stacking method by forming an extremely smooth CNT layer and by activating CNT with a unique laser irradiation method. A test panel proves good emission property and uniformity.

Fabrication of carbon-nanotube field-emitter array using polymer insulator

This article reports the fabrication process of a carbon-nanotube (CNT) field-emitter array with the silicon-ladder polymer insulator polyphenylsilsesquioxane (PPSQ), whose feature is heat resistance, high breakdown voltage, and low outgassing. CNT islands are formed with a screen-printing method, polymer-insulator coating is carried out (8 μm in thickness), and the gate electrodes are deposited, followed by patterning of the electrodes. PPSQ insulator is applied reactive ion etching (RIE) to reveal CNT emitters. Because of using mixed gases of CF4 and O2, the etching rate for CNT is half that for PPSQ, there is a margin to stop etching with enough CNT left. After reactive ion etching, emission-current density from the revealed CNT is degraded, so laser activation treatment is applied and the emission current density is boosted by a hundredfold. In the case of the triode mode, the laser condition was chosen to prevent gate damage and to improve emission characteristics. Current density of 3 mA/cm2 is obta...

Investigation into Short-Circuit Ruggedness of 1.2 kV 4H-SiC MOSFETs

The shout-circuit ruggedness of prototype 1.2kV SiC MOSFETs has been investigated. The short-circuit measurements were carried out at 25 °C and 125 °C with a dc bus voltage of 800 V and an on/off state gate voltage of +20/-10 V. The small difference in tfail between 25 °C and 125 °C indicates that the destructive breakdown occurs at temperatures much higher than 125 °C. The temperature at destructive breakdown estimated from the Wunsch-Bell formula is about 1400 °C. At such high temperatures, intrinsic carriers are increased markedly and generated heat leads to the destructive breakdown. tfail of all the SiC-MOSFETs studied is longer than 10 μs, meaning that the short-circuit ruggedness satisfies system requirements. These results show that the SiC-MOSFETs are promising for power electronics applications.

4H-SiC Power Metal?Oxide?Semiconductor Field Effect Transistors and Schottky Barrier Diodes of 1.7 kV Rating

4H-SiC metal–oxide–semiconductor field effect transistors (MOSFETs) and Schottky barrier diodes (SBDs) of 10 A/1.7 kV rating were fabricated and characterized. Suitable design of a drift layer and a junction termination realized stable avalanche breakdown of 1.8 kV. Relatively low on-resistances of 8.3 mΩ cm2 for the MOSFET and 2.2 mΩ cm2 for the SBD were successfully recorded. Temperature dependence of the static characteristics of the SBD showed positive temperature coefficient in both the avalanche breakdown voltage and the differential on-resistance. The MOSFET and SBD were assembled into an SiC module. Its dynamic characterization revealed that the switching loss reduction in the SiC module was as much as 86% in comparison with that of the conventional Si counterpart under a moderate switching condition.

53.1: Fabrication of CNT Emitter Array with Polymer Insulator

A new method of fabricating CNT emitter array using polymer insulator with low outgassing has been developed. A dry etching process without the damage on the CNT has been found and it proved to decrease the turn-on voltage. Better emission properties than conventional insulator has been obtained.

SiC-MOSFET Structure Enabling Fast Turn-On and -Off Switching

High speed switching is desired to reduce switching losses of SiC-MOSFETs. In order to realize SiC-MOSFETs capable of high speed switching, we numerically evaluated the electric field induced in SiC-MOSFETs during switching using an equivalent circuit model. Based on the evaluation, we designed a SiC-MOSFET, which successfully demonstrated high speed switching with a dV/dt of over 70 V/ns.

A New LCD with an Input Function Using Conventional Electrodes for Both Display and Input

The research and development of the information terminals and systems which enable an operator to input data viewing characters and graphs-shown on the display have been increasing. Moreover, as the necessity of inputting graphic or hand written data increases, several types of data tablets become used in these systems widely.[l][2] It is an important problem how easily an operator can have an interactive conversation with these systems. However, conventional data tablets are inconvenient for the operator because they are set apart from a display monitor.