COMPARISON OF PDGETIPT AND NIGEAU OHMIC CONTACTS TO N-GAAS AND PDGETIPT AND TIPD CONTACTS TO P(-GAAS())

NiGeAu and PdGeTiPt ohmic contacts to n-GaAs and TiPd and PdGeTiPt ohm ic contacts to p(+)-GaAs are examined by comparing their contact resis tances, chemical intermixing as determined by Auger electron microscop y, interface structure as determined by transmission electron microsco py, and surface roughness as determined by surface profiling all measu red as a function of annealing time and temperature. The n-PdGeTiPt co ntact annealed for short times, less than or equal to 15 s, and at low temperatures, less than or equal to 395 degrees C, was superior to th e NiGeAu contact because it had a comparable contact resistance, less interface mixing, better lateral homogeneity, and a smoother surface. However, its contact resistance increased substantially with the annea ling time and temperature, whereas the NiGeAu contact was relatively u naffected. For all annealing times and temperatures except the one at 550 degrees C, the TiPd contact to p(+) GaAs was superior as it had a lower contact resistance and a comparable amount of interface intermix ing, lateral homogeneity, and surface roughness. However, it had a com plete chemical breakdown at 550 degrees C, whereas the PdGeTiPt contac t resistance remained relatively stable.