Influence of the Metallization Composition and Annealing Process Parameters on the Resistance of Ohmic Contacts to n-type 6H-SiC

Abstract

For silicon carbide, the problem of obtaining low-resistance ohmic contacts with improved service characteristics remains topical despite a significant body of experimental data. The influence exerted by the composition of Ni and TiAl metallization, alloying parameters, additional doping of the contact layer of silicon carbide (SiC) with N⁺ nitrogen ions, and the crystallographic Si- or C-face on the resistance of ohmic contacts  to n-6H-SiC  is examined.  It is  found  that the greatest influence on how ohmic contacts to n-6H-SiC are formed is exerted by the alloying process resulting in a decrease in the contact resistance by approximately six times. The process of additional doping with N⁺ also reduces the contact resistance by nearly a factor of four. It is found that low-resistance contacts can be obtained on both faces with approximately the same low resistance. TiAl metallization is optimal for the C-face, and Ni metallization, for the Si-face. This choice of metallization makes it possible to obtain ohmic contacts on both polar faces with approximately the same resistances on the order of 2.5 × 10^–4 Ω cm².