Effects of thermal treatments on the structural and electrical properties of Ni/Ti bilayers Schottky contacts on 6H-SiC

In this paper, the effects of thermal treatments on the structural and electrical properties of the system Ni/Ti/6H-SiC were studied. Ni/Ti bilayers were prepared by e-beam evaporation onto 6H-SiC substrates and annealed under vacuum between 400 and 650degreesC. Above 450degreesC a solid state reaction involving the metallic bilayer started and resulted in the formation of nickel and titanium silicides. The electrical characterization of the metal contact showed an increase of the Schottky barrier, from a value of 0.91 eV (typical of Ti) in the as deposited, towards 1.39 eV (typical of Ni2Si) in the high temperature annealed samples, along with a decrease of the device leakage current. The results, beyond giving interesting insights into the complicated reaction mechanism of the Ni/Ti system with SiC, may find applications in the control of the electrical properties of Schottky barriers on SiC.