Enhanced Current Gain (>250) in 4H-SiC Bipolar Junction Transistors by a Deep-Level-Reduction Process

We demonstrate 4H-SiC bipolar junction transistors (BJTs) with an enhanced current gain over 250. High current gain was achieved by utilizing optimized device geometry as well as optimized surface passivation, continuous epitaxial growth of the emitter-base junction, combined with an intentional deep-level-reduction process based on thermal oxidation to improve the lifetime in p-SiC base. We achieved a maximum current gain (β) of 257 at room temperature and 127 at 250°C for 4H-SiC BJTs fabricated on the (0001)Si-face. The gain of 257 is twice as large as the previous record gain. We also demonstrate BJTs on the (000-1)C-face that showed the highest β of 439 among the SiC BJTs ever reported.