Prepartion And Research On Transport Characteristics Of Niobium-based With Nanoporous Structure

In recent years,many strategic areas related to the national economy and the people's livelihood,such as quantum communication,have hoped to make breakthroughs in single photon detection research.At present,the wide study in single photon detection is the superconducting nanowire single photon detector,but its preparation is very relying on the progress of superconducting materials and etching nanowires required for device preparation,the principle is based on the detection of thin film materials from the superconducting state to the metal state transition,and the development of single photon detectors is greatly constrained.At present,many research groups have carried out research on the superconducting insulation phase transition,which provides a new idea for the preparation of single photon devices,that is,detecting from the insulation state to the metal state transition,avoiding the previous detection principle for superconducting thin-film materials.The performance dependence is that the prepared thin film is too thin to easily lose the superconductivity or the thin film is too thick to affect the detection efficiency of the device.Therefore,this thesis chooses to study the preparation and transport properties of Bi-based superconducting thin films with nanoscale hole arrays,and explores two ways to realize superconducting insulated phase transitions on Nb-based superconducting thin films in single photon detection.The main contents are as follows:Firstly,a niobium and a niobium nitride superconducting thin film were fabricated on a silicon substrate and a MgO substrate by DC magnetron sputtering method.Through changing the preparation parameters,the niobium film that the thickness was 17.9 nm,the superconducting transition temperature was 7.60 K and a root mean square(RMS)roughness of 0.32 nm finally prepared.And the niobium nitride thin film having a 11 nm thick,a superconducting transition temperature of 13.5 K and a RMS roughness of 0.54 nm was reproducibly and stably prepared.In addition,a high-quality ultra-thin NbN thin film with a thickness of 6 nm and a superconducting transition temperature of 9.4 K can be stably prepared.Second,through the combination of anodized alumina oxide(AAO)template and reactive ion beam etching,a nanoporous niobium thin film was fabricated.The porous niobium films with different thicknesses were prepared and transported.The results show that the film thickness can regulate the property of thin film with porous structure : the thinner the film thickness,the stronger the regulation and the easier to achieve the insulation phase transition;The thick film,which was easy to connect the triangular region between the hole and the hole forming an island of local superconductivity,made the system superconducting.The logarithm of the electrical transport of the niobium film prepared by sputtering for 80 seconds shows a metal state.Finally,a porous structure was formed on the prepared NbN film with good quality,the etching time was changed,and the wall thickness of the hole produced by the different etching time was used to explore the regulation effect of the superconducting insulator phase transition of the NbN film.Transport test results show that NbN film with different etch times have a transition from superconducting to insulator states.Magnetic transport results show that the intermediate state samples have magnetic resistive oscillations,and the oscillating period and theoretical calculations are consistent with each other,indicating that the magnetic resistive oscillation is the quantum magnetic flux oscillation of the Cooper pair.