In situ optical monitoring of two-dimensional crystal growth in layer-by-layer chemical vapor deposition of YBa2Cu3Ox

We have applied an in situ optical growth monitoring method to layer-by-layer chemical vapor deposition of YBaCuO thin films and observed a staircaselike change in reflectance. Once step corresponds to one cycle of source gas supply combination and growth of one unit cell of the YBa2Cu3Ox structure. This step is completed when Cu is supplied for the third time and the final layer consisting of a unit cell is applied. This result suggests that two-dimensional crystal growth of YBa2Cu3Ox occurs. The calculation of reflectance change is consistent with the hypothesis that the reflectance change is due to layer-by-layer growth of YBaCuO.