SI GEXSI1-X HETEROJUNCTION BIPOLAR-TRANSISTORS WITH THE GEXSI1-X BASEFORMED BY GE ION-IMPLANTATION IN SI/

We have fabricated n-p-n, Si/GexSi1-x heterojunction bipolar transisto rs (HBT's) with the GexSi1-2 base formed by high-dose Ge implantation followed by solid phase epitaxy, The fabrication technology is a stand ard self-aligned, double polysilicon process scheme for Si with the ad dition of the high-dose Ge implantation. The transistors are character ized by a 60 nm-wide neutral base with a Ge concentration peak of appr oximate to 8 at.% at the base-collector junction. The HBT's show good electrical characteristics and compared to Si homojunction transistors show lower base resistance, larger values of current gain, and a lowe r emitter-to-collector transit time.