Masanori Takata

Low leakage current Schottky barrier diode

low forward voltage drop 0) compared to that of a pn junction diode, but has a serious problem of a large leakage current. No solution to the problem has been found which does not cause fatal increase in the FVD. We have examined a structure, in which the parallelly arranged Schottky junctions are put between the pn junctions. The device parameters to improve the trade-off between FVD and leakage current density were found through calculations. The effectiveness of the parameten was coniirmed by the experiments using the new structure. A Schottky barrier diode (SBD) has an advantage of

An overvoltage self-protected thyristor with a structure to predict breakover voltage

A new concept for an overvoltage self-protected thyristor was theoretically analyzed and the thyristor manufactured. Its breakover operation is basically a combination of punchthrough and avalanche phenomena. Temperature dependence of the original structure in this thyristor is 5% from 20 to 125/spl deg/C. A second device which has a function to predict breakover voltage was also produced. The difference in temperature dependence of breakover voltage for both devices was investigated by an analytical model. Structures offering improved characteristics were proposed. The breakover voltage decrease of the developed structures at high temperature could be made equal to that of the original structure by a slight modification of the breakover region.

A new concept, overvoltage self-protected thyristor

A new concept, overvoltage self-protected thyristor was theoretically analyzed and then fabricated. Its breakover operation is a combination of punchthrough and avalanche phenomena. Breakover voltage of the fabricated device is lowered several % at temperature from 20 to 125°C. This value corresponds to one third of that of the simple avalanche type device. Breakover power endurance of the device with 6kV breakover voltage amounts to several hundred kW. Compared with the simple avalanche type device, this newly developed device has twice the power endurance.