Fabrication of Au/Ti TESs for Optical Photon Counting

High efficiency and negligible dark-count rates of transition-edge sensor (TES) microcalorimeters as single photon detector at telecommunications and optical visible wavelengths make them powerful tools for quantum information and quantum computation. In this work we report details on the fabrication of Au/Ti for photon counting and analyse the effects on the critical temperature and the transition steepness of the structuring process and wiring material. Au/Ti films deposited by electron-beam at substrate temperature lower than 435 K show sharp transition and reproducible Tc. Moreover, we observe that TES with Al wiring are more stable and have better characteristics of TES with Nb wiring. Using 20 micron×20 micron Ti/Au TES single photon detection has been obtained in the UV-visible range.