高温超导外延薄膜YBα_2Cu_3O_(7-x)中空位型缺陷的低能正电子寿命研究

利用脉冲低能正电子束系统测量了脉冲激光沉积法、磁控溅射法和多源共蒸法制备的高温超导外延薄膜ＹＢａ２Ｃｕ３Ｏ７－ｘ的低能正电子寿命谱。结果表明。除块材中普遍存在的正电子浅捕获中心外，还大量含有块材中缺乏的正电子探捕获中心，并且其尺度随温度的降低而长大。脉冲激光沉积法制备高温超导外延薄膜ＹＢａ２Ｃｕ３Ｏ７－ｘ的正电子寿命和沉积条件（衬底温度及空气分压）的关系研究表明，这种深捕获缺陷的种类与沉积条件无关，而缺陷浓度随衬底温度的降低及空气分压增高而增加

Low energy positron lifetime studies on open-volume defects of epitaxialhigh temperature superconductor thin film

By using a pulsed low energy positron lifetime system, the positron lifetime spectra were measured of the high- temperature superconducting epitaxial thin film YBa2Cu3O7-x samples prepared by the pulsed laser deposition (PLD), magnetron- sputtering method and evaporation method, respectively. It is found that besides shallow positron trapping centers there ace a number of deep trapping centers which the bulk material lacks. At low temperature the deep trapping centers have a tendency to enlarge. The relationship between positron lifetime and the deposition conditions (substrate temperature and partial air pressure) of the PLD films indicates that the defect type is independent of the deposition conditions and the defect concentration increases with decreasing substrate temperature or rising partial air pressure.