Research On The Preparation Of Superconductive Nb Mental Film On Quartz Substrates

High quality superconducting niobium(Nb) metal film has high mechanical strength and high resistance to corrosion, of which superconducting transition temperature(Tc) is up to 9.3 K and superconducting properties are not reduced even after repeated temperature cycling. Therefore, since it was discovered, it has been quickly used in national defense, health care, energy and other fields. Currently, it is usually prepared by magnetron sputtering. Nb metal has high melting point and easy to absorb oxygen, which affects the quality in many factors during the preparation process. This paper focused on the preparation of Nb film by DC magnetron sputtering on a quartz substrate. The main contents and conclusion are as follows:First, we prepared Nb film by DC magnetron sputtering on a quartz substrate and analysised the influence of different parameters on the Nb film by XRD, AFM, four-probe resistance tester, PPMS and other analytical ways. The study reveals that the niobioum polycrystalline thin films were developed in a body-centered cubic structure, while the(110) crystal orientation get preferential growth. Different parameters influence the crystallization. Through experiment, we found that sputtering pressure, substrate temperature, film thickness and other parameters have a significant influence on the crystallization conditions, the internal stress, the surface morphology. By optimizing the parameters, the superconducting niobioum films equipped with better crystallization, smooth and compact surface(RMS of 2.88 nm), small internal stress(-0.31 GPa) and the superconducting transition temperature of 9.07 K were developed on quartz substrate.By improving the preparation conditions for niobium films combined with growth pattern of niobium films, the effect of substrate bias on the structure and performance of niobium films prepared by magnetron sputtering were studied. We discovered that certain substrate negative bias(-100 V) would cause niobium film resistivity to increase, which do bad to the electric properties of niobium films. Additionally by making full use of the gas-absorbing property and increasing the sputtering power at 3.5×10-4 Pa, we prepared high quality niobium superconducting films with high crystalline quality, smooth and compact surface(RMS is less than 5 nm) of which internal stress is about-0.20 GPa and superconducting transition temperature is 9.3 K.In addition, for the preparation of spherical niobioum superconducting thin films which can be used to study magnetic levitation technology, the thickness distribution of spherical niobioum films with different remote state was also studied by optimizing the structure of the magnetron sputtering equipment and designing a spherical substrate tray. The spherical niobioum metal film equipped with good adhesion, low surface resistance(average resistance 4.5 ?, mean square error of the resistance 0.19) and uniform film thickness distribution is prepared on a solid spherical quartz substrate with smooth surface.