Femtosecond-laser-induced modifications on a 4H-SiC surface and their application to low-temperature diffusion at the Ni/SiC interface

Abstract

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.