| Autor: |
Lee, Sanghan, Chen, Ke, Baek, Seung Hyup, Dai, Wenqing, Moeckly, Brian H., Li, Qi, Xi, Xiaoxing, Rzchowski, Mark S., Eom, Chang Beom |
| Předmět: |
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| Zdroj: |
IEEE Transactions on Applied Superconductivity; Jun2009 Part 3 of 3, Vol. 19 Issue 3, p2811-2814, 4p, 1 Black and White Photograph, 1 Chart, 4 Graphs |
| Abstrakt: |
We have grown MgB2 thin films using RF magnetron sputtering combined with a pocket heater. This technique relies on a low-pressure environment for sputter deposition of boron and a high-pressure environment for thermal evaporation of Mg. We have obtained superconducting MgB2 thin films using substrate temperatures of 480-540°C and Mg furnace temperatures of 730-750°C. The Tc onset of the thin films increased from 21.6 K to 35 K with increasing substrate temperature due to better crystallization. Higher boron deposition rates also increase Tc. The highest Jc, of the films at 5 K and near zero magnetic field is 1.5 MA/cm2 which is comparatively lower than the films grown using a pocket heater with boron deposition by chemical vapor deposition or electron beam evaporation. The chemical composition analysis by WDS exhibits a high concentration of oxygen and carbon in the MgB2 films, which is due to a high background base pressure and an impure B sputtering target. These results suggest that the Tc, Jc, and resistivity of MgB2 films are mainly determined by an inhomogeneous microstructure and superconducting percolation paths through impurity phases such as MgO. By comparison with carbon or oxygen doped films, the high impurity content in the sputtered MgB2 films might act as method to achieve high Hc2. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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