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To realize the benefits of SiC power electronics and optical-driving device technology, we present optically activated SiC power transistors for pulsed-power application. Although limited by the indirect bandgap of SiC, the transistor employs a bipolar structure with an internal current gain, which amplifies the photogenerated current and therefore has the capability to reduce the optical-triggering power requirement. The transistors are fabricated on an n-type 4H-SiC substrate with switch-on triggered by a short UV (337.1 nm) laser pulse with 0.5-mJ optical energy. The transistor successfully switches 1200 V with an FWHM of about 180 ns, a rise time of less than 20 ns, and a fall time of about 200 ns. This initial work forms the basis for the further development of high-speed and energy-efficient SiC-based optically controlled power switches for high-temperature and high-power applications.
Date of Publication: Oct. 2010