Abstract: We discuss technology issues in deposition of high temperature superconducting YBCO thin films by reactive evaporation. Several key components are necessary to make this a robust manufacturing process. The oxygen pocket heater is the most significant part and determines most of the repeatability and uniformity issues. Additionally, a reliable and repeatable measurement of the atomic beams is necessary for good control of the cation stoichiometry. Quartz crystal monitors (QCM) are currently used for rate control, although their current implementation limits them to rate control at the level of 5%. A tunable-diode laser sensor has been compared directly against a QCM and demonstrated to agree to 1% of the QCM flux measurements. Because of the ability of these new laser senors to measure the deposition flux in the sample position, they seem the most promising technology for vapor flux measurement and control. !6
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