Ti/Al/Si Ohmic Contacts for both n-Type and p-Type 4H-SiC

An ohmic contact process by using tri-layer materials for a source contact of a silicon carbide (SiC) metal oxide semiconductor field effect transistor (MOSFET) is proposed. The authors validate its extremely low contact resistance for both n-type and p-type SiC by a simple process. The characteristics of Ti/Al/Si ohmic contacts were measured by using the transfer length method (TLM). We examined the dependence of the contact resistance on the thickness of each layer of Ti/Al/Si. Then, it is found that Ti/Al/Si contacts with an appropriate thickness show excellent ohmic properties for both n-type and p-type SiC. N-type specific contact resistance (ρn) of 3.7 × 10-6 Ω cm2 and p-type specific contact resistance (ρp) of 1.7 × 10-4 Ω cm2 are obtained with Ti (20 nm) /Al (30 nm) /Si (30 nm).