Numerical simulation and experimental investigation of laser pulse duration effects on Ni/SiC ohmic contacts during ultraviolet laser annealing

Abstract

Silicon carbide (SiC) is considered as a competitive candidate for power semiconductor devices owing to its outstanding comprehensive properties. Laser annealing is an efficient method for preparing Ni/SiC ohmic contact, which is essential for optimizing the performance of SiC-based devices. However, to the best of our knowledge, the impact of laser pulse duration on Ni/SiC contact properties has not been systematically studied yet. Here, we report an ohmic contact engineering of SiC wafer to reveal the specific correlation between pulse durations and ohmic contact characteristics. A transient heat transfer model was established using COMSOL Multiphysics to simulate the temperature dynamic evolution under varying pulse durations, revealing that shorter pulse durations generate higher peak temperatures. Experimental studies were carried out by annealing Ni/SiC samples with pulse durations of 70 ns, 90 ns, and 110 ns, followed by analyses of surface morphology, interfacial microstructure, and electrical characteristics of the contacts. The results show that the surface roughness increases as the pulse duration decreases, the alloyed interface layer becomes thick, and the alloy phase shifts toward a Si-rich composition. Specific contact resistances on the order of 10^-4 Ω∙cm² were observed for all pulse durations, owing to the formation of uniform interface structures. The formation mechanism of ohmic contacts was further discussed based on energy band theory. This study highlights the potential of optimizing laser pulse duration to improve ohmic contact performance and offers valuable insights for the design and fabrication of SiC-based devices.