Patent ID: 7304334

Claim:
A bipolar junction transistor (BJT) comprising: a silicon carbide (SiC) substrate; an epitaxial SiC base region on the SiC substrate, the epitaxial SiC base region having a first conductivity type; and an epitaxial SiC emitter region on the SiC substrate, the epitaxial SiC emitter region having a second conductivity type, different from the first conductivity type, and having a first portion on the SiC substrate and a second portion on the first portion remote from the SiC substrate, the second portion having a higher carrier concentration than the first portion, wherein the epitaxial SiC base region comprises: a first p-type epitaxial SiC layer on the SiC substrate; a first p-type epitaxial SiC region on the first p-type epitaxial SiC layer, the first p-type epitaxial SiC region having a higher carrier concentration than the first p-type epitaxial SiC layer; and a second p-type epitaxial SiC region on the first p-type epitaxial SiC region remote from the first p-type epitaxial SiC layer, the second p-type epitaxial SiC region having a higher carrier concentration than the first p-type epitaxial SiC region.