An array of SIN tunnel junctions as a sensitive thermometer

Journal article, 2008

We have fabricated and measured an array of superconductor-insulator-normal metal (SIN) tunnel junctions for the purpose of using it as a sensitive thermometer. An increase in the temperature responsivity of dV/dT similar to 5 mu V mK(-1) for ten junctions is observed from dV/dT similar to 1 mu V mK(-1) for a single junction. We then used such an array thermometer to measure the temperature stability of the Heliox AC-V cryogen-free refrigerator. We have been able to measure a temperature stability of +/- 250 mu K over a period of 8 h with a temperature resolution of +/- 100 mu K.