High-temperature reliability of Ni/Ti/Nb ohmic contact on p-type 4H-SiC

Abstract In this study, the thermal stability of Ni/Ti and Ni/Ti/Nb ohmic contact on p-type 4H-SiC were investigated for 100 h at 400 °C in N 2 environment. The results demonstrated that lower contact resistance and higher thermal stability could be achieved with the Ni/Ti/Nb candidate. After 100 h aging, the specific contact resistance of the Ni/Ti/Nb sample slightly increased from 2.56 × 10 −3 to 3.04 × 10 −3 Ω cm 2 . X-ray diffraction results showed that Ni 2 Si, Ti 3 SiC 2 and Nb 6 C 5 compounds contributed to low contact resistance and high-temperature reliability. By adding Nb, the surface of the Ni/Ti/Nb/4H-SiC ohmic contact becomes smoother than that of the Ni/Ti/4H-SiC ohmic contact. The metal/4H-SiC interface of the ohmic contacts was observed after 100 h aging by using TEM measurement. For the Ni/Ti/Nb sample, the excess carbon atoms were collected by the formation of Nb–C compounds and then increased high temperature reliability and reduced contact resistivity.