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Superconducting thin films of Tl‐Ba‐Ca‐Cu‐0 have been prepared by a unique hybrid technique that combines electron beam evaporation with organometallic chemical vapor deposition (OMCVD). Multilayer thin films of Ba‐Ca‐Cu‐O are prepared by sequential electron beam evaporation of BaF2, CaF2, and Cu sources onto single crystal MgO (100) or yttria‐stabilized zirconia (YSZ) substrates followed by annealing in a water vapor‐saturated oxygen atmosphere. Thallium is then incorporated into these films in either of two ways: (1) via OMCVD using thallium(cyclopentadienide) as the source, or (2) rapid annealing of the Ba‐Ca‐Cu‐O film in the presence of bulk thallium superconductor. The resultant films primarily consist of single phase TlBa2Ca2Cu3Ox with the Cu‐O planes preferentially oriented parallel to the substrate surface. Resistivity measurements indicate superconducting onset temperatures above 120 K with zero resistance by 104 K. By eliminating the water vapor anneal, residual fluoride, originating from the sources, may be left in the film. This leads to formation of predominantly c‐axis oriented crystallites of the TlBa2CaCu2Ox phase.

Raman spectroscopy was employed to study Y–Ba–Cu–O films prepared by multilayer, reactive sputtering from separate Y, Cu, and Ba0.5Cu0.5 targets. A set of films having the composition YxBa2CuyOz with 0.7 < x < 1.8 and 2.8 < y < 3.5 and critical temperature with zero resistance, Tc(R = 0), ranging from 25 to 90 K was studied with the Raman technique. The correlation between Raman data and critical temperature, Tc, was investigated. This technique provides important information concerning the film crystallinity, homogencity, and impurity content (including other phases) which is useful in judging the quality of high Tc superconducting films. We also found that the rapid thermal annealing process is a very efficient way to reduce chemical reactions between the film and the substrate.

We discuss experiments and theory directed towards the development of a buckytube cold field emitter array electron cathode.

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