Laser Alloying Nickel on 4H-Silicon Carbide Substrate to Generate Ohmic Contacts

摘要

To obtain ohmic contacts on silicon carbide semicondanneuctors commonly a thin metal layer is deposited onto the semiconductor wafer, followed by a rapid thermal process to transform the result-ing Schottky diode into an ohmic contact. Here, we report on an alternative laser based process re-placing the conventional rapid thermal treatment. A continuous wave infrared fiber laser is em-ployed to locally alloy nickel coated silicon carbide to an ohmic contact. Our results show that ohm-ic contacts are achieved with laser powers between 100 W and 300 W over an irradiated area on the order of 7 mm diameter. Electrical resistances of the generated ohmic contacts are measured down to 6.5 Ω, depending on laser power. Temperature dependent measurements of the resistance reveal a negative temperature coefficient of 11 mΩ/K.