Fabrication of Au/Ti TESs for Optical Photon Counting

Abstract

High efficiency and negligible dark-count rates of transition-edge sensor\ud (TES) microcalorimeters as single photon detector at telecommunications and optical\ud 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\ud photon counting and analyse the effects on the critical temperature and the transition\ud 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\ud 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

Ti/Au TES to Discriminate Single Photons

“…The experimental data here shown are obtained illuminating Ti/Au TESs deposited on top of a SiN covered Si substrate [7] with an active area of 20 µm × 20 µm and 10 µm × 10 µm and detector thicknesses ranging between 80 nm and 90 nm. The proximity effect, between titanium and gold, lowers the film critical temperatures down to 120-130 mK.…”

Optical Transition-Edge Sensors Single Photon Pulse Analysis

“…The experimental data analysed in this work have been obtained at INRiM with a TiAu TES, whose fabrication process has been described in [8]. The photons are absorbed directly by the TiAu layer with an active area of and .…”

Thin Gold Covered Titanium Transition Edge Sensor for Optical Measurement

“…4 (Color online) The transition temperature (a) and sheet resistance (b) of the thin-gold covered Ti and bare-Ti as a function of the Ti thickness temperature of thin-gold covered Ti films is slightly low, however, its difference is within tens of mK for the same titanium thickness. The T C with 10 nm gold can be described with T C = T C,0 (1 − 0.54 d Au /d Ti ) where T C,0 is the critical temperature of bulk Ti [6]. To apply the above equation, we used measurement results obtained by bare titanium films shown as closed circles in Fig.…”

“…Currently, the TES-based optical photon detectors have great impacts on quantum information because of its ability to determine the quantum states precisely with high efficiency [1][2][3]. Various type of superconductors are proposed for the TES films; tungsten, titanium, hafnium, titanium/gold bilayer [4][5][6]. In our group, a titanium superconductor has been used, which has the transition temperature over 300 mK.…”

“…As those devices, Ti/Au TESs are already reported as X-ray microcalorimeters and Sub-mm bolometers and showing reliable performance [6]. As an optical TES, however, the usage of the gold film is undesirable because of its high reflectance, which would lower the system detection efficiency.…”