Photo-thermal electron transport in YBCO-bismuth junctions

Electron transport analysis of photo-thermal studies carried out using a 10 mW He-Ne laser and YBCO-bismuth thick (50 mu m) film junctions is presented. In single stage geometry a 50 mV photo-voltage develops across the junction at 77 K with a bias current of 15 mA. A 0.08 K-1 temperature coefficient of resistance was found over the superconducting to normal state transition (80-90 K) for the junction which leads to a responsivity of 5 V W-1. In a two stage thermopile cascade configuration a thermoelectric voltage of 20 mV was found which corresponds to a temperature difference of 0.25 degrees C between the hot and cold ends at 77 K.