Laser synthesis of ohmic contacts in silicon carbide having Schottky diode characteristics before laser treatment

Abstract

Ohmic contacts are fabricated in silicon carbide substrates by a direct write laser synthesis technique. The substrates exhibited the Schottky diode characteristics before laser treatment. Forward and reverse current-voltage characteristics are measured at room and liquid nitrogen temperatures to analyze the temperature and voltage dependence of resistance. Rectifying contacts in single crystalline beta-silicon carbide and alpha-silicon carbide are transformed to ohmic contacts by laser irradiation. Because of a large change in the resistance due to laser irradiation, polycrystalline alpha-silicon carbide, which transformed from insulating to conducting, is chosen for analyzing the transformation mechanism. An observed microbridge across the micropores and melt-zone refinement of the silicon carbide grains may contribute to the mechanism for improved conductivity.Ohmic contacts are fabricated in silicon carbide substrates by a direct write laser synthesis technique. The substrates exhibited the Schottky diode characteristics before laser treatment. Forward and reverse current-voltage characteristics are measured at room and liquid nitrogen temperatures to analyze the temperature and voltage dependence of resistance. Rectifying contacts in single crystalline beta-silicon carbide and alpha-silicon carbide are transformed to ohmic contacts by laser irradiation. Because of a large change in the resistance due to laser irradiation, polycrystalline alpha-silicon carbide, which transformed from insulating to conducting, is chosen for analyzing the transformation mechanism. An observed microbridge across the micropores and melt-zone refinement of the silicon carbide grains may contribute to the mechanism for improved conductivity.