Kinetic study of interfacial solid state reactions in the Ni/4H-SiC contact

Investigation of the relatively low temperature reaction between Ni nanolayer film and 4H-SiC substrate provides valuable insights into studies of the fundamental properties of SiC Schottky diodes. A quantitative description of chemical kinetics of Ni/SiC contact formation has been studied via deposition of about 50 nm Ni film on 4H-SiC (Si terminated surface) by magnetron sputtering and subsequent annealings at temperatures of 500-700 degrees C. X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) techniques were used to investigate the interface reaction products upon annealing and element distribution across the reaction layer. It is found that the thermodynamically stable silicide Ni2Si begins to form at the contact interface as a result of sample annealing above 600 degrees C, which associated with producing carbon distributed at the surface and at the interface of the silicide with the SiC substrate. The kinetic process is described to mainly include the solid state interface reactions and the diffusion of components through the produced layer of silicides. When the diffusion layer is thick enough (more than 100 nm), the kinetic feature is thought to be diffusion controlled, which follows the parabolic law. The active energy of Ni silicide formation was derived as (135.0 +/- 19.51) kJ mol(-1). (c) 2009 Elsevier B.V. All rights reserved.