Development of Thermal Kinetic Inductance Detectors Suitable for X-ray Spectroscopy
We report on the development of thermal kinetic inductance detectors (TKIDs) suitable to perform X-ray spectroscopy measurements. The aim is to implement MKIDs sensors working in thermal quasi-equilibrium mode to detect X-ray photons as pure calorimeters. The thermal mode is a variation on the MKID classical way of operation that has generated interest in recent years. TKIDs can offer the MKIDs inherent multiplexibility in the frequency domain, a high spatial resolution comparable with CCDs, and an energy resolution theoretically limited only by thermodynamic fluctuations across the thermal weak links. Microresonators are built in Ti/TiN multilayer technology with the inductive part thermally coupled with a metal absorber on a suspended SiN membrane, to avoid escape of phonons from the film to the substrate. The mid-term goal is to optimize the single-pixel design in terms of superconducting critical temperatures, internal quality factors, kinetic inductance and spectral energy resolution. The final goal is to realize a demonstrator array for a next generation thousand pixels X-ray spectrometer. In this contribution, the status of the project after one year of developments is reported, with detailed reference to the microresonators design and simulations and to the fabrication process.
KeywordsThermal mode Thermal kinetic inductance detectors TKID Microwave kinetic inductance detectors MKIDs Super-conductive microresonators Superconducting film Thin film Micromachining X-ray spectroscopy
This work is carried out in the frame of the KIDS_RD R&D Project funded by the Istituto Nazionale di Fisica Nucleare (INFN) in the Commissione Scientifica Nazionale 5 (CSN5). We also acknowledge previous support from Fondazione Cariplo, through the Project Development of Microresonator Detectors for Neutrino Physics (Grant International Recruitment Call 2010, ref. 2010–2351), and from INFN through the MARE Project.