Physical properties of amorphous molybdenum silicide films for single-photon detectors
Xiaofu Zhang, Ilya Charaev, Huanlong Liu, Tony X Zhou, Dong Zhu, Karl K Berggren, Andreas Schilling
Abstract
Abstract We systematically investigated the physical properties of amorphous Mo x Si 1− x films deposited by magnetron co-sputtering. The critical temperature T c of Mo x Si 1− x films increases gradually with the Mo stoichiometry x , and the highest T c = 7.9 K was found in Mo 0.83 Si 0.17 , where homogeneous films with the maximum Mo content can be obtained. The thick films of Mo 0.83 Si 0.17 show surprising degradation in which the onset of zero-resistivity is suppressed below 2 K. The thin Mo 0.83 Si 0.17 films, however, reveal robust superconductivity even with thickness d ≈ 2 nm. We also characterized wide microwires based on the 2 nm thin Mo 0.8 Si 0.2 films with wire widths 40 and 60 μ m, which show single-photon sensitivity at 780 nm and 1550 nm wavelength.