The effect of O plasma upon the growth of thin films was investigated. It was found that decreasing the growth temperature introduced excess O vacancies, which were formed in a non-equilibrium state regardless of whether a plasma was used. At growth temperatures as low as 500C, the crystallinity of thin films which were grown in molecular O was superior to that of films grown in O plasma, because the growth conditions close to the decomposition line of the 123 compound enhanced surface migration. At temperatures above 540C, no significant difference could be detected between films which were grown in molecular O and those which were grown in O plasma. This was suggested to be because, at higher temperatures, thin-film growth was dominated by the thermal energy which was supplied by the heated substrate.

A.Tsukamoto, M.Hiratani, S.Akamatsu: Applied Physics Letters, 1993, 62[26], 3516-8