Extremely Thermal Stable Ni/W/TaSi_2/Pt Simultaneous Ohmic Contacts to N-Type and P-Type 4H-SiC

摘要

Studying the ohmic contacts formed on ion-implanted SiC layers is fundamental to understand and to predict the behavior of practical devices. Ohmic contacts to n- (1×10sup19/sup cmsup−3/sup) and p-type (1×10sup20/sup cmsup−3/sup) ion-implanted 4H-SiC using Ni/W/TaSisub2/sub/Pt were investigated. No degradation of the specific contact resistance nor a minute change of the surface morphologies was observed after 300 h of 500 oC thermal treatment in air. From auger electron spectroscopy (AES) depth profiles, it was found that the oxidation of the protective platinum silicide overlayer significantly slowed down further migration of oxygen to the SiC interface. In addition, Pt and W played the role of mutual blocking, which guarantees the stability of the contact. This research suggests that the contacts are very promising for applications in harsh environments, where the simultaneously completed both on n-and p-type stability ohmic contacts is crucial.