In Situ Optical Monitoring of Growth Rate and Surface Roughness of YBa2Cu3O7-y Films in Chemical Vapor Deposition

Abstract
An optical method for in situ monitoring of film thickness has been applied to growth of YBa2Cu3O7-y films by chemical vapor deposition. Reflectivity change is monitored at an incident angle of 78° from the film growing on MgO(100) substrate. An oscillation in the reflection intensity resulting from interference inside the YBa2Cu3O7-y layer is observed with the deposition time. The deposition rate calculated from the oscillation frequency agrees well with the value estimated from chemical analysis of the film. Increase of CuO precipitate with increasing Cu content in the film results in a corresponding decrease of the reflection intensity due to the scattering of laser light at the film surface. Therefore, this simple method provides an effective means for growth control of superconducting thin film by chemical vapor deposition.