Characterization of AuGeNi Ohmic Contacts on n-GaAs Using Electrical Measurements, Auger Electron Spectroscopy and X-Ray Diffractometry

Ohmic contacts obtained by deposition of (AuGeNi + AuNi) films on n-GaAs substrates were studied. The specific contact resistance ( rho sub c ) was used to characterize the electrical behaviour of the contacts and the interface microstructure was analysed using Auger electron spectroscopy (AES) and X-ray diffractometry. rho sub c was shown to be inversely proportional to the semiconductor carrier concentration. The lowest rho sub c value for a conventional annealing (in a resistive furnace) was obtained at 470 deg C for 3 min. The possibility was observed of obtaining contacts with identical rho sub c values using both conventional or rapid thermal annealing (RTA), but AES analysis showed that the interface reacted layer was wider for the first process. X-ray diffractometry has shown that various compounds appear due to annealing, e.g. beta -AuGa, Au sub 7 Ga sub 2 and Ga sub 4 Ni sub 3 . The relationships between the electrical and the structural characteristics of the contacts are discussed. Graphs, Diffraction patterns. 16 ref.--AA