Deposition methods of high-Tc superconductors

摘要: Abstract Depositing high-Tc oxide superconductors poses the most demanding challenge for thin film technology. The complexity of superconductor formation parallels materials themselves. Making films these requires transporting all elements in proper stoichiometry onto substrates, forming correct crystal structure and layer stacking sequence, providing sufficient oxygen to form superconducting phase. Evaporation separate metal constituents generally is a low-pressure process. A high oxygen-atom arrival rate at substrate under this restriction can successfully be provided by rf-plasmas, microwave-generated atomic oxygen, electron cyclotron resonance (ECR) sources, ozone-generation techniques. Sputter deposition suffers from negative ion bombardment substrate. This minimized geometries where held outside plasma, applying sputtering pressures with attendant short mean free paths. Chemical vapour (CVD) still shows some problems volatile barium sources. Nevertheless, it represents one promising techniques large-scale applications. In pulsed laser (PLD) technique, high-energy pulse ultraviolet or visible radiation vaporizes ejects surface material which impinges on subsequently. process runs far off thermal equilibrium, therefore produces an extremely good stoichiometric transfer. Furthermore, parameters chosen allow wide dynamic range between molecular beam heavy sputter conditions. there are practically no restrictions regarding reactive gas atmosphere chamber. Highest quality epitaxial YBa2Cu3O7−δ made date have been produced way. Other approaches include, e.g. spraying, chemical spray pyrolysis, sol-gel spin casting, dipping, electrodeposition. traditional vacuum techniques, more novel processes, likely finding general acceptance