Net of YBCO and LSMO Thermometers for Bolometric Applications

Abstract

In this work, two types of perovskite oxide materials with high temperature coefficients have been chosen as thermometers for use in bolometric applications: superconducting YBa2Cu3O7-δ (YBCO) and colossal magnetoresistive La2/3Sr1/3MnO3 (LSMO) thin films. Two different temperature ranges are concerned: around 90 K for YBCO, since they were operated at the superconducting-metal transition and around the room temperature for LSMO. The temperature coefficient ratio and the noise were carefully measured. Best NET values of 3×10-8 K.Hz-1/2 at 1 Hz, 90 K and 5 mA current bias for YBCO and 1.3×10-6 K.Hz-1/2 at 1 Hz, 300 K and 1.5 mA current bias for LSMO were obtained. Results are compared to literature and, in the case of room temperature applications, to other types of materials such as semiconductors (a-Si, a-Si:H, a-Ge, poly SiGe) and other oxide materials (semiconducting YBCO, VOx, other manganite compounds). Finally, the possible use of these thermometers with such low NET characteristics for the fabrication of both membrane-type bolometers for mid-infrared detection and antenna coupled bolometers for THz applications is discussed.