TEM Observations of Ti/AlNi/Au Contacts on p-Type 4H-SiC

摘要

Improved AlNi-based ohmic contacts to p-type 4H-SiC have been achieved using low energy ion (Al~+)implantation, the addition of a thin Ti layer, and a novel two-step implant activation anneal process. AlNi/Au contacts with and without Ti were studied, which resulted in contact resistivities around 1.8×10~(-4) Ω-cm~2 and 2.0×10~(-3) Ω-cm~2 respectively. Even though these values were higher than those of the Ti/AlNi/W system, which was the focus of previous studies, the reduced anneal temperature (650 to 700°C) implies that Ti/AlNi/Au is a promising composite configuration. Cross-sectional TEM and EDX were used to investigate the interfacial structure of the contacts. One possible mechanism for the improved ohmic contact behavior is that the addition of Au and Ti resulted in a reduction barrier height.