We investigated low-temperature diffusion at the Ni/SiC interface with the assistance of femtosecond laser-induced modifications. Cross sections of the laser-irradiated lines of two different pulse energies -0.84 and 0.60 J/cm 2 in laser fluencewere compared before and after annealing at 673 K. At the laser fluence of 0.60 J/cm 2 , a single flat Ni-based particle was formed at the interface after annealing. The SiC crystal under the particle was defect-free. The present results suggest the potential application of femtosecond laser-induced modifications to the low-temperature fabrication of contacts at the interface without introducing crystal defects, e.g., dislocations and stacking faults, in SiC.

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We carried out cross-sectional transmission electron microscopy to investigate the diffusion at the Ni/SiC interface enhanced by femtosecond-laser-induced modifications. The surface of a 4H-SiC crystal was irradiated with femtosecond laser pulses along lines, and a Ni film was then deposited. A thin modified layer was introduced by densely irradiating the SiC surface with line spacing close to the laser-beam diameter. After annealing, a layered structure was formed at the Ni/SiC interface, composed of a C layer sandwiched between the layers of Ni and Ni–Si alloy. The formation of Ni-silicide, i.e., Ni2Si and NiSi, was detected by micro-Raman spectroscopy. The distribution of C visualized by electron energy loss spectroscopy clearly shows that C atoms were released from the dissolved SiC and subsequently diffused through the Ni-silicide layer towards the Ni film surface.