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Effects of an Ar and CF 4 RF plasma mixture, in which the base electrode surface was cleaned prior to oxide barrier formation, on Nb/Nb oxide/Pb Josephson tunnel junction characteristics have been investigated. Good quality junctions with less leakage current (V m =39.3 mV) and no knee at voltages just above the gap voltage have been obtained using the CF 4 cleaning process (CFCP). It is speculated that the chemical etching reaction and a carbon layer generated on the cleaned Nb surface by CF 4 plasma play an important role in achieving a cleaned based electrode surface free from damage and the formation of a good quality oxide tunnel barrier, respectively.
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Michikami et al. (1983) studied this question.
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