Carbon effect on neutral base recombination in high-speed SiGeC HBTs

We have presented the performances and electrical behavior of high-speed SiGeC HBTs having enhanced NBR by carbon insertion in excess. The current gain is strongly reduced, so that BV CEO increases by 0.5 V, and the f T times BV CEO product shifts from 340 to 423 GHz.V, which offers new possibilities for HBTs optimization, notably by increasing collector doping. Thanks to the NBR, the current gain dependency with temperature above 300 K is reduced, which is interesting for applications such as power amplifiers. The current gain evolution with V BE is explained by trap saturation, which was confirmed in simulations by inserting a trap level in the base gap. The band gap dependency with carbon insertion is also demonstrated and was developed in the final paper