Silicon carbide and silicon carbide : germanium heterostructure bipolar transistors

In this letter, we report on heterostructure bipolar transistors (HBTs) based on silicon carbide (SiC) and a silicon carbide:germanium (SiC:Ge) alloy. The SiC:Ge base alloy was formed by the ion implantation of Ge into p-type 4H-SiC and subsequent annealing. HBT mesa structures were fabricated using a reactive ion etching process. The incorporation of Ge was found to increase the gain and the Early voltage of the devices. A common-emitter current gain (beta) of greater than 3 was measured for the SiC:Ge HBTs. Homojunction SiC transistors were fabricated as a reference using the same process (except no Ge in the base region) and exhibited a beta of 2.2. The transistors exhibited high breakdown voltages (> 50 V without passivation), that typify SiC-based devices. These results indicate that SiC:Ge is a promising material for use in SiC-based heterostructure devices. (C) 2001 American Institute of Physics.