Si/Ge/sub x/Si/sub 1-x/ HBTs with the Ge/sub x/Si/sub 1-x/ base formed by high dose Ge implantation in Si

We have fabricated n-p-n Si/Ge/sub x/Si/sub 1-x/ heterojunction bipolar transistors with the Ge/sub x/Si/sub 1-x/ base formed by high dose Ge implantation followed by rapid thermal annealing at 1000/spl deg/C for 10 s. The fabrication technology is a standard self-aligned, double polysilicon process scheme for Si with the addition of the high dose Ge implantation. The transistors are characterized by a 60 nm wide neutral base with a Ge concentration peak of /spl ap/7 at.% at the base-collector junction. For the first time using this fabrication technology, good static electrical characteristics are demonstrated. Compared to Si homojunction transistors with similar values of current gain and Early voltage, the Ge/sub x/Si/sub 1-x/ devices show base resistances more than two times lower.