Project objectives are 1) Realizing a high-gain, high-voltage and high-temperature monolithic SiC-GaN-OGBT (optically-gated bipolar transistor) triggered in a non-latched manner using a low-power short-wavelength photonic source; 2) Reducing photonic-triggering power by optimization of optical-absorption efficiency using a GaN-SiC heterojunction structure; 3) Reducing OGBT conduction drop using localized charge-compensation and conductivity modulation; 4) Experimental characterizations.
Intellectual Merit: The emitter and base of the OGBT are made of GaN while the collector is made of SiC, thus achieving optical efficiency and retaining excellent breakdown voltage and temperature characteristics of SiC. OGBT eliminates oxide-reliability problem at high temperature and breakdown-voltage limitation in insulated-gate devices. N-type SiC substrate-based OGBT structure circumvents the problem of unavailability of P-type substrate required for N-channel SiC IGBTs. Optical triggering of OGBT eliminates negative-gate-bias referencing need for N-substrate SiC IGBT. Superjunction-based charge-compensation technique in SiC-GaN-OGBT yields high blocking voltage and low forward-conduction drop. Proposed work explores ohmic-contact issues for connecting N-GaN to P-SiC and hetero-epitaxial growth of GaN on SiC. OGBT has implications for high-power, high-temperature, and high-frequency power system with enhanced reliability due to optical isolation, EMI and parasitic-noise immunity, device stress mitigation, and synergistic integration of photonic and wide-bandgap device structures.
Broader Impacts: Broad applications include fly-by-light, electric ship, electric/hybrid vehicles, telecommunication, spacecrafts, FACTs, pulsed power, and microwave power amplifiers. The results of the research will be integrated into 2 undergraduate/graduate courses. The project will support 1 Ph.D. student and aims to incorporate, per year, 4 senior-design and undergraduate-research students (including 2 under-represented and 1 honor-role student), and 1 middle-school student.
