OHMIC CONTACTS TO N-TYPE SILICON-GERMANIUM

We have studied both alloyed metal and ion-implanted Ohmic contacts to n-type silicon/silicon germanium heterostructures. We found that gold /antimony contacts can distort low temperature mobility measurements, and seriously degrade a sample after a short time. A more reliable alt ernative alloy is silver/antimony. We also found phosphorous ion-impla nted contacts, annealed to 600 degrees C for 30 min, to be reliably Oh mic and of low resistivity at low temperatures. (C) 1996 American Inst itute of Physics.