Investigation of the properties of Pd/Ge/Au/Pd/Au ohmic contacts to n-GaAsformed with different ambients

We investigate the effects of different ambients during alloying on the ele ctrical resistance of electron-beam-evaporated Pd/Ge/Au/Pd/Au contacts to n -GaAs. For an H-2/N-2 ambient, the lowest contact resistivity of 2.1 x 10(- 6) Ohm cm(2) was obtained after annealing at 400 degrees C for 15 s. For an N-2 ambient the lowest contact resistivity of 2.2 x 10(-6) Ohm cm(2) was o btained after annealing at 400 degrees C for 45 s. X-ray diffraction, cross -sectional scanning electron microscopy, and Auger electron spectroscopy we re utilized in this study. We found that the formation of AuGa and Pd5Ga2 c ompounds is responsible for the observed low contact resistivity. (C) 1999 Elsevier Science B.V. All rights reserved.