Amorphous molybdenum silicon superconducting thin films (original) (raw)
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Superconducting single-photon detector made of MoSi film
Superconductor Science and Technology, 2014
We fabricated and characterised nanowire superconducting single-photon detectors (SSPD) made of 4 nm thick amorphous Mo x Si 1−x film. At 1.7 K temperature the best devices exhibit a system detection efficiency of 18% at 1.2 µm wavelength of unpolarised light with dark count rate of 10 per second rate, a fast characteristic response time of about 6 ns and low timing jitter of 120 ps.
Materials Development for High Efficiency Superconducting Nanowire Single-Photon Detectors
MRS Proceedings, 2015
Superconducting nanowire single-photon detectors (SNSPDs) based on ultra-thin films have become the preferred technology for applications that require high efficiency single-photon detectors with high speed, high timing resolution, and low dark count rates at near-infrared wavelengths. Since demonstration of the first SNSPD using NbN thin films, an increasingly larger number of materials are being explored. We investigate amorphous thin film alloys of MoSi, MoGe, and WRe with the goal of optimizing SNSPDs for higher operating temperature, high efficiency and high speed. To explore material adequacy for SNSPDs, we have measured superconducting transition temperature (T c ) as a function of film thickness and sheet resistance, as well as critical current densities. In this paper we present our results comparing these materials to WSi, another amorphous material widely used for SNSPD devices.
High-efficiency superconducting nanowire single photon detectors based on amorphous Mo0.75Ge0.25
CLEO: 2014, 2014
We demonstrate high-efficiency superconducting nanowire single-photon detectors (SNSPDs) fabricated from MoSi thin-films. We measure a maximum system detection efficiency (SDE) of 87 ± 0.5 % at 1542 nm at a temperature of 0.7 K, with a jitter of 76 ps, maximum count rate approaching 10 MHz, and polarization dependence as low as 3.4 ± 0.7 % The SDE curves show saturation of the internal efficiency similar to WSi-based SNSPDs at temperatures as high as 2.3 K. We show that at similar cryogenic temperatures, MoSi SNSPDs achieve efficiencies comparable to WSi-based SNSPDs with nearly a factor of two reduction in jitter.
High-efficiency superconducting nanowire single-photon detectors fabricated from MoSi thin-films
We demonstrate high-efficiency superconducting nanowire single-photon detectors (SNSPDs) fabricated from MoSi thin-films. We measure a maximum system detection efficiency (SDE) of 87 +- 0.5 % at 1542 nm at a temperature of 0.7 K, with a jitter of 76 ps, maximum count rate approaching 10 MHz, and polarization dependence as low as 3.4 +- 0.7 % The SDE curves show saturation of the internal efficiency similar to WSi-based SNSPDs at temperatures as high as 2.3 K. We show that at similar cryogenic temperatures, MoSi SNSPDs achieve efficiencies comparable to WSi-based SNSPDs with nearly a factor of two reduction in jitter.
We fabricated and characterized nanowire superconducting single-photon detectors made of 4 nm thick amorphous Mo x Si −x 1 films. At 1.7 K the best devices exhibit a detection efficiency (DE) up to 18% at 1.2 μm wavelength of unpolarized light, a characteristic response time of about 6 ns and timing jitter of 120 ps. The DE was studied in wavelength range from 650 nm to 2500 nm. At wavelengths below 1200 nm these detectors reach their maximum DE limited by photon absorption in the thin MoSi film.
Optics express, 2016
We present low temperature nano-optical characterization of a silicon-on-insulator (SOI) waveguide integrated SNSPD. The SNSPD is fabricated from an amorphous Mo<sub>83</sub>Si<sub>17</sub> thin film chosen to give excellent substrate conformity. At 350 mK, the SNSPD exhibits a uniform photoresponse under perpendicular illumination, corresponding to a maximum system detection efficiency of approximately 5% at 1550 nm wavelength. Under these conditions 10 Hz dark count rate and 51 ps full width at half maximum (FWHM) timing jitter is observed.
Characterization of superconducting thin film growth on silicon substrates
Journal of Crystal Growth, 1988
superconducting thin films by MOTsRe25 single-target magnetron sputtering at various temperatures on sapphire substrates were prepared. Sharp superconductive transitions and T c values above 10 K were achieved, and the deposited films showed a good metallic behavior. According to structural analyses (EDS and X-rays), all the samples have the same stoichiometry as the target and, even at low deposition temperatures, they exhibit the A15 phase. From measured residual resistivities and superconducting critical temperatures the theoretical BCS surface resistances were estimated and compared to those o Mos0Re4o films, presented in a previous work. Both these alloys, in fact, befi ~ characterized by low surface resistances and high critical fields, are good c ~didates as coating films in r.f. cavities.
Characterization of MoSi superconducting single-photon detectors in magnetic field
IEEE Transactions on Applied Superconductivity, 2014
We investigate the response mechanism of nanowire superconducting single-photon detector SSPD made of amorphous Mo x Si 1-x . We study the dependence of photon count and dark count rates on bias current in magnetic fields up to 113 mT at 1.7 K temperature. The observed behavior of photon counts is similar to the one recently observed in NbN SSPD. Our results show that the detecting mechanism of relatively high energy photons does not involve the vortex penetration from the edges of the film, and on the contrary, the detecting mechanism of low energy photons probably involves the vortex penetration from the film edges.
Activation Energies in MoSi/Al Superconducting Nanowire Single-Photon Detectors
Physical Review Applied
Superconducting nanowire single-photon detectors (SNSPDs) are receiving the interest of the scientific and industrial communities due to their unparallel high performances in the infrared. However, even though the fabrication process permits the achievement of about 98% efficiency and less than 1 cps darkcount rate, the physical mechanism inducing the detection remains unclear. It is clear however that normal core vortices play a crucial role. In this work we investigate the role of vortices in two-dimensional (2D) molybdenum silicide SNSPDs of different widths covered with an Al layer through the analysis of the switching current distributions from the superconducting to resistive regime, in a wide interval of temperatures from 4.5 K down to 10 mK. This analysis provides the energy scales of different mechanisms that are responsible for fluctuations and dark counts in SNSPDs. We consider two models based on vortices, the unbinding of vortex-antivortex pairs (VAPs) and vortices hopping over the edge barrier (VH) and we underline the differences among different devices made by different materials. We also estimate the energy scales of similar Nb-TiN and NbN devices and compare the results. The lower activation energies obtained for MoSi/Al devices, explain the peculiarity of this material to work at longer wavelengths with a higher quantum detection efficiency.