The Fabrication And Reasearch Of NbN And NbSi Flims Applying In SNSPDs

Single-photon detection is a key technology in science research, which is widely applied in many fields, including quantum key distribution, quantum computing, fluorescent detection, weak optical signal imaging and etc. Superconducting nanowire single-photon detector (SNSPD), which used the non-equilibrium hot electron effects in superconducting ultra-thin film. It has the advantages of high repetition rate, wide response spectrum and low dark count rate. By fabricating optical cavity and waveguide structures, SNSPDs are able to achieve high detection efficiency of above 80%. SNSPDs have the best synthesis performance among varies single-photon detectors therefore they have received abroad attention.During the fabrication of SNSPDs, high quality thin-film is very crucial.This thesis aims at the fabrication of NbN thin film and NbSi film with low energy gap. By optimizing the condition, we have fabricated high quality thin-film for SNSPDs. The details of the structures and operation methods of both systems are introduced in our thesis. We provide the process routing of experiments of both thin-films in details. At last, we do a lot of researches of physical properties of the thin-films. We measured the thickness, structure, elements, surface morphology of the thin-films by step profiler, EDX, XRD, AFM, SEM. We measured the superconducting transition temperature of the NbN thin-films and the NbSi thin-films with liquid helium Dewar liquid helium Dewar and PPMS respectively. We have accumulated a lot of sheet resistance data of different NbN film thickness and characterized the thickness and uniformity of NbN film we have made by sheet resistance characterization system.According to the result of analysis, the Tc of NbN films of 4 nm thickness on MgO is over 12.5K and.The Tc of NbN films of 6 nm thickness on Si is over 7.4K,and.The Tc of NbN films of 6 nm thickness on Si-SiOx is over 7.38K.We also made a progress of the initial preparation of the NbSi film with the Tc of 3 k by co-sputtering and 65% of it is Nb while 30% is Si. During this program we change the voltage, the barometric pressure and the distance. These efforts have been or will be used in the preparation of infrared and far-infrared band superconducting single-photon detector.And we supplement and provide the characterization of film thickness by sheet resistance measurement. And we have already used it in the fabrication of SNSPDs and get good results.