Journal of vacuum science & technology b vol:9 issue:2 pages:228-235
Rutherford backscattering spectrometry and Auger electron spectroscopy are combined to study the interdiffusion behavior in alloyed Ni/Au/Te/Ni/GaAs ohmic contacts. The data are correlated to the results of electrical measurements to allow for a discrimination between the different ohmic contact models. Good ohmic behavior is found to coincide with the presence of a thin (congruent-to 200 angstrom) Te-rich (5-10 at. %) layer in the substrate surface layers. This result and the diffusion data on nonohmic behaving contacts can most consistently be interpreted in the frame of the graded crystalline and/or amorphous heterojunction model.