Laser Processing of Ti Contacts for Ohmic Behavior on P-Type 4H-SiC

This work explores a key challenge in power device fabrication: the formation of ohmic contacts on p-type 4H-silicon carbide (SiC). We demonstrate a selective, low thermal budget approach using single titanium (Ti) metallization combined with pulsed laser annealing (PLA), as an alternative to both metallic multilayer stacks and conventional high-temperature annealing. By applying PLA with fluences above 3.6 J/cm², Ti contacts exhibit linear current-voltage (<i>I</i>-<i>V</i>) behavior, indicating effective ohmic contact formation, with over 50% improvement in conduction observed at 3.8 J/cm². Cross-sectional transmission electron microscopy (TEM) and elemental mapping reveal that higher fluences promote deeper SiC consumption, and the formation of a continuous, epitaxially regrown SiC layer, bonded to a uniform titanium carbide (TiC) layer extended deeper into the p-doped region. This structure supports efficient charge transfer and strong interfacial bonding. Furthermore, increasing fluence drives the transient liquid phase composition from Ti-rich toward a more balanced Ti-Si-C composition, promoting the formation of ternary phases enriched in Si and C that enhance interfacial stability and electrical performance. This work demonstrates that PLA offers precise control over interfacial reactions and contact microstructures, offering a scalable, selective, and thermally efficient approach for ohmic contacts on p-type 4H-SiC, advancing the development of high-performance, next-generation SiC-based power electronics.