Alloying of ohmic contacts to n-type 4H-SiC via laser irradiation

In this study, we present results on alloying nickel as ohmic contact material to n-type 4H-SiC via a continuous wave fiber laser with different laser beam powers and processing times. The laser system exhibits an emitting wavelength of 1070 nm and a beam propagation factor M2 smaller than 1.1. Contact resistance was determined by current-voltage measurement using two- terminal contact resistance method. The results indicate that a laser beam power of at least 100 W is mandatory to initialize contact silicidation. Although the contact resistance is improvable by longer processing times, our experiments outline the much higher impact of laser beam power to contact silicidation compared to processing time. For laser beam powers of 300 W and processing times of 0.5 s a contact resistance of 6.5 comparable to contacts alloyed in a lamp heated furnace at 910 °C for 2 min with a contact resistance of 10.3, was achieved.