  We have developed the deposition technology of WSi thin films 4 to 9 nm thick
with high temperature values of superconducting transition (Tc~4 K). Based on
deposed films there were produced nanostructures with indicative planar sizes
~100 nm, and the research revealed that even on nanoscale the films possess of
high critical temperature values of the superconducting transition (Tc~3.3-3.7K
) which certifies high quality and homogeneity of the films created. The first
experiments on creating superconducting single-photon detectors showed that the
detectors SDE (system detection efficiency) with increasing bias current (Ib)
reaches a constant value of ~30% (for 1550 nm) defined by infrared radiation
absorption by the superconducting structure. To enhance radiation absorption by
the superconductor there were created detectors with cavity structures which
demonstrated a practically constant value of quantum efficiency >65% for bias
currents Ib>=0.6Ic. The minimal dark counts level (DC) made 1 s^-1 limited with
background noise. Hence WSi is the most promising material for creating
single-photon detectors with record SDE/DC ratio and noise equivalent power
(NEP).
