  We fabricated and characterised nanowire superconducting single-photon
detectors (SSPDs) made of 4 nm thick amorphous Mo$_x$Si$_{1-x}$ films. At 1.7 K
the best devices exhibit a detection efficiency up to 18% at 1.2 um wavelength
of unpolarised light, a characteristic response time of about 6 ns and timing
jitter of 120 ps. The detection efficiency was studied in wavelength range from
650 nm to 2500 nm. At wavelengths below 1200 nm these detectors reach their
maximum detection efficiency limited by photon absorption in the thin MoSi
film.
