Device fabrication on epitaxial Si-Ge alloys

PMOS transistors, p--n junctions and diffused resistors have been fabricated in Si--Ge alloy having a range of Ge content from 0 to 38%. The p--n junctions showed lower forward voltage drops than would be expected from simple band-gap lowering information. A Ge build-up at the surface may be causing this. MOS transistors exhibited low mobilities in the range 20-50 cm exp 2 /V s. The mobility value was affected by the surface condition and smoother surface areas resulted in the higher values of mobility. Diffused resistors had very high resistor values compared to control samples fabricated on Si. Contact resistance problems were suspected but not proven to be the cause. 12 ref.--AA