Characterization of a Superconducting NbSi Transition Edge Sensor for TeSIA

We report on the performance of a superconducting NbSi transition edge sensor (TES), which is co-evaporated on a suspended SiO/SiN/SiO trilayer membrane. The temperature sensitivity coefficient
$(\alpha)$
calculated from the measured resistive transition curve is as high as 200. The current-voltage characteristics were measured at bath temperatures varying from 288 mK to 440 mK using a two-stage SQUID amplifier, from which the thermal conductance (G) was found to be 345 pW/K. We also measured the current noise at different bias voltages at 288 mK. The obtained electrical noise equivalent power (NEP) from its calculated current responsivity and measured current noise is about
$8\times 10^{-17}\ \hbox{W}/\surd{\hbox{Hz}}$
. In addition, the preliminary measurement results of time domain multiplexing scheme based on the superconducting quantum interference devices (SQUIDs) and an application specific integrated circuit (ASIC) are presented.