Researchers led by Prof. Sheng-Cai Shi, Purple Mountain Observatory, Chinese Academy of Sciences, are developing a THz superconducting imaging array (TeSIA) for the 5-meter THz telescope (DATE5) to be constructed at Dome A. Aiming at the final goal of 32x32 array at 350 m, a prototype of 8x8 Ti Transition edge sensor (TES) array at 850 μm has been developed.
The Ti microbridge with 16 μm x16 μm is integrated with a twin-slot antenna to couple the THz radiation. After the fabrication of Ti TES array, windows are opened in the SiN membrane on the backside, and KOH wet etching is performed to remove the silicon substrate underneath the Ti microbridge. The thermal conductance is reduced to 800 pW/K from 3000 pW/K, and the measured effective response time is 5 μs. In order to improve the uniformity, the thickness of Ti film is increased to 64 nm, and its properties after KOH wet etching keep the same as before, which is very important for array operation with time-domain multiplexing.
Fig. 1 Measurement setup for electrical properties of the 8 × 8 Ti TES array. The TES device is mounted on the mixing chamber (MC) stage of dilution cooler. The TES current is read out using a single-stage SQUID thermally anchored on the 1 K cold plate. The work by Wen Zhang, Wei Miao, Zhen Wang, Dong Liu, Jia-Qiang Zhong, Xiao-Hui Guo, Feng Wu, Qi-Jun Yao, and Sheng-Cai Shi, accepted by IEEE transactions on applied superconductivity, has been published online