ABSTRACTNovel Ni/WSi/Ti/Pt composite Ohmic contacts to n-SiC were investigated as a function of annealing temperatures up to 1000°C. The onset of Ohmic behavior occurred at annealing temperatures of 900°C. Annealing at temperatures between 950°and 1000°C yielded excellent Ohmic behavior. At these temperatures the contact-SiC interface was smooth, defect free and characterized by a narrow Ni2Si reaction region. The annealed contacts possessed atomically smooth surface morphologies and exhibited minimal contact expansion. The residual carbon, resultant from SiC decomposition, was constrained by reaction with the WSi and Ti metallization layers forming carbide phases of W and Ti. The locations of the carbide phases were spatially distant from the metal semiconductor interface. Our results demonstrate that the Ni/WSi/Ti/Pt composite Ohmic contact maintains the desirable electrical properties associated with Ni contacts and possess excellent interfacial, compositional and surface properties which are required for reliable high power and high temperature device operation.
Study of SiC device for pulsed power switching circuit
