Optimization of a thermoelectric IR-detector for low working temperature

摘要

Thermoelectric IR-detectors have been developed for working at a temperature of 170 K in the CIRS experiment of the designated interplanetary CASSINI mission. Thermoelectric legs of p- and n-type are soldered isolated one from another to a metallized ceramic substrate. Pyramidal legs are formed by electric discharge machining (EDM). A thin gold foil is welded to the cones and blackened for high absorption of radiation. Characterization measurements are carried out to correlate detector properties with the influence of preparation process and material used. Thermoelectric behaviour is described by measuring the current-voltagecharacteristics from liquid nitrogen up to room temperature. Material of various composition within the pseudobinary systems Bi2Te3-Sb2Te3 (for p-type) and Bi2Te3-Bi2Se3 (for n-type) has been used for detector preparation. By choosing material of proper doping the maximum of the figure of merit could be shifted towards lower temperatures.