High Voltage, High Current 4H-SiC Bipolar Power Devices

The rapid development of the technology of producing high quality single crystal SiC wafers and thin film presents the opportunity to fabricate solid-state devices with power-temperature capability far greater than devices currently available. This capa- bility is ideally suited for military and commercial applications requiring high blocking voltage switches and amplifiers capable of large currents with relatively low voltage drops. While conventional silicon power devices are already being used near their limits of operating power and temperaturet the potential of SiC is-just beginning to be demon- strated. Small area 4H-silicon carbide thyristors have been demonstrated that can block 375 V and achieve 1 Amp with a forward voltage of 4.0 V. This corresponds to a high current density of 1000 A/cm,@. These devices showed exo-pllent,characteristics UP to 500-C. The leakage cu-.rents at 500-C were only 4.8xlO-J A/cat, yielding a hii3h lion-off" current ratio of 100. The measured t- for these devices ranged from 360 rLkc to 640 nsec, meaning these devices can operate at much higher frequencies (>150 kHz) than typical Si thyristors. The phase I effort will focus on the fabrication of a new type of SiC bipolar switching device that should have higher current densities and much more efficient-gating than the SiC thyristor design used previously. The Phase I first focus on it effort will beion implantation and epitaxial growth technology vital to this new structure. Then two sets of the bipolar devices, each having opposite polarity, will be fabricated and evaluated.