GE ION-IMPLANTATION IN SI FOR THE FABRICATION OF SI GEXSI1-X HETEROJUNCTION TRANSISTORS/

Epitaxial Si/GexSi1-x heterojunctions were formed by high dose Ge ion implantation in Si followed by solid phase epitaxy. This technique was adopted for fabricating Si/GexSi1-x heterojunction n-p-n bipolar tran sistors (HBT). We used a standard self-aligned, double polycrystalline silicon process for Si with the addition of the high dose Ge implanta tion. The transistors are characterized by a 60 nm wide neutral base w ith a Ge concentration peak of approximate to 8 at.% at the base-colle ctor junction. The devices show very good static electrical characteri stics, and compared with Si homojunction transistors with similar valu es of current gain and Early voltage, show base resistances more than two times lower. In addition to the HBTs, also the feasibility of GexS i1-x metal-oxide-semiconductor field-effect transistors (MOSFET) by io n implantation has been explored by investigating the GexSi1-x oxidati on process.