Development of iridium TES by pulsed laser deposition with a Nd : YAG laser

The use of cryogenics micro calorimeters with Transition Edge Sensors for high-resolution spectroscopy for space applications puts several constraints on the detector's performances. Among several requirements, the long term stability of TES from a chemical and physical point of view is one of the most important. Iridium is a very interesting material for TES fabrication due to its excellent chemical stability and low transition temperature. Starting from the promising results we had with a cryogenic microcalorimeter with TES made of an Ir single crystal, we are developing a procedure to produce patterned Ir thin films by means of the Pulsed Laser Deposition (PLD). PLD with an infrared laser, in UHV, allows very clean evaporation process, good efficiency (about 4 nm/shot) and low dissipated power in the vacuum chamber (about 1 W). We have applied a lift-off mask technique that allows to heat the substrate during the deposition, which improves the adhesion and the thermal conductivity and circumvents the needs of very aggressive etchant solutions.