Effect of ion-implantation temperature on contact resistance of metal/n-type 4H-SiC with ar plasma treatment

It has been reported that Ar plasma treatment on the n-type 4H-SiC surface before metal deposition can reduce the contact resistance. In that work, the n ⁺ layer was formed by ion implantation at room temperature (RT). In this paper, it is found that Ar plasma treatment on the high-temperature (HT) implanted n ⁺ layer degrades but not improves the contact resistance. A composition of RT/low-energy and HT/high-energy ion implantation can achieve low sheet resistance of the n ⁺ layer and low contact resistance simultaneously. A twofold mechanism is proposed that the amorphous interfacial layer produced by Ar plasma treatment reduces the Schottky barrier height and the defects generated by RT ion implantation enhance current conduction by trap-assisted tunneling.