Laser doping mechanism of 4H-SiC by KrF excimer laser irradiation using SiNx thin films

In this study, nitrogen is doped into 4H-SiC by irradiating 4H-SiC with a SiNx thin film and a KrF excimer laser. The doping depth profile, crystal structure, electrical properties, and surface roughness results are analyzed to evaluate the excimer-laser doping mechanism. High-concentration doping is possible at a fluence of 2.5 J cm⁻² and 10 shots, while maintaining the 4H-SiC crystal structure via solid-phase diffusion. However, changes in the 4H-SiC crystalline state are observed upon liquid-phase diffusion at a fluence of ≥2.8 J cm⁻². At a fluence of 2.5 J cm⁻² and 100 shots, nitrogen can be deeply diffused via solid-phase diffusion; however, an amorphous layer is formed on the surface and there is an increase in contact resistance.