Dresden 2006 – scientific programme

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TT: Tiefe Temperaturen

TT 7: Superconductivity & Solids At Low Temperature - Poster Session

TT 7.47: Poster

Monday, March 27, 2006, 14:00–17:45, P1

Morphology of epitaxial Al/AlO_x/Al trilayers — •Jonathan Eroms¹, H.W. Zandbergen¹, R. Delhez², A.H. Verbruggen¹, C.J.P.M. Harmans¹, and J.E. Mooij¹ — ¹Kavli Institute of Nanoscience Delft, TU Delft, The Netherlands — ²Department of Materials Science and Engineering, TU Delft, The Netherlands

For increasing the Josephson junction quality in our superconducting qubit circuits we investigate growth of epitaxial aluminum films in a molecular beam epitaxy system. Here we present results on the crystalline structure of the bottom and top Al electrode in an Al/AlO_x/Al layer stack. We monitor the growth in situ by RHEED and ex situ with x-ray diffraction and high-resolution TEM. The bottom Al layer can be grown epitaxially in (111) orientation on Si(111) surfaces. The Al surface is oxidized by introducing a low pressure of oxygen into the growth chamber, and an amorphous AlOx film is formed. Growing aluminum onto this layer still gives a (111) oriented film, but in different rotational orientations. Depending on the oxygen exposure, the top Al layer either follows the orientation of the lower Al film, but with strong incorporation of twin crystals, or forms a random (111) texture.