Direct fabrication of Cu/Cu2O composite micro-temperature sensor using femtosecond laser reduction patterning

Abstract

Micro-temperature sensors, which composed of a Cu2O-rich sensing part and two Cu-rich electrodes, were directly fabricated by femtosecond laser reduction patterning of CuO nanoparticles. Patterning of the microstructures was performed by laser scanning with pitches of 5, 10, and 15 µm. Cu2O-rich micropatterns were formed at the laser scan speed of 1 mm/s, the pitch of 5 µm, and the pulse energy of 0.54 nJ. Cu-rich micropatterns that had high generation selectivity of Cu against Cu2O were fabricated at the laser scan speed of 15 mm/s, the pitch of 5 µm, and the pulse energy of 0.45 nJ. Electrical resistivities of the Cu2O- and Cu-rich micropatterns were approximately 10 Ω m and 9 µΩ m, respectively. The temperature coefficient of the resistance of the micro-temperature sensor fabricated under these laser irradiation conditions was −5.5 × 10−3/°C. This resistance property with a negative value was consistent with that of semiconductor Cu2O.