Fig. 1. (a) Mo0.8Si0.2 film deposition on a thermally oxidized silicon wafer. (b) Fabrication of electrode pads composed of Ti and Au by lithography and liftoff. (c) Spin-coating with electron-beam resist PMMA. (d) Meandering nanowire patterning by EBL. (e) Development in methyl isobutyl ketone (MIBK) diluted in isopropanol (IPA). (f) Fixing to obtain the mask pattern. (g) Pattern transfer to the film by RIE. (h) Removal of the residual resists using N-methyl pyrrolidone.

Fig. 2. (a) Comparison of the resistivity versus temperature curve of the 6.5 nm (red) and 100 nm (black) films. (b) Tcd as a function of Rs obtained by fitting the universal scaling law proposed by Ivry et al. (c) TEM image of the film, the insert shows the diffraction ring pattern. (d) The surface roughness was measured using AFM. The roughness RMS is 0.5 nm.

Fig. 3. (a) Complex refractive index of the Mo0.8Si0.2 film. (b) The simulation of the optical absorption of the nanowires with different stoichiometric ratios (1550 nm wavelength).

Fig. 4. Estimation of the total etching time for the Mo0.8Si0.2 film, and the optimization of the nanowires etching, representing: (1) under-etching, (2) optimum etching, (3) over-etching.

Fig. 5. SEM images of the Mo0.8Si0.2 nanowires fabricated using the PMMA resist, the nanowires with a line width of 50±2  nm, a period of 200 nm, and an active area of 20 μm×20  μm.

Fig. 6. (a) I-V curves of single pixel SNSPD with 50 nm-width nanowires at different operating temperatures, ranging from 75 mK to 2.2 K. The inset figure presents ISW as a function of temperature. (b) The photon counts as functions of the bias current at different operating temperatures for the single pixel SNSPD. (c) Internal detection efficiency (IDE) and dark count rate (DCR) as functions of the normalized bias current for 50 nm-width nanowires. (d) Normalized photon counts as a function of the bias current for the 4-pixel based Mo0.8Si0.2−SNSPD at 2.2 K, the inset in the lower right corner depicts the I-V curve of one of the pixels.

Table 1. Comparison of the Different Stoichiometric Ratios of the MoSi Films in Terms of Bulk Tc, Complex Refractive Index, and FDTD Simulation Results (1550 nm Wavelength)^a