Growth of YBa2Cu3O7-δ thin films in pulsed laser deposition: influence of target, substrate and deposition rate

The growth of smooth, high quality, c -axis thin films of optimally doped YBa2Cu3 O7-δ on (001) MgO substrates has been studied using pulsed laser deposition. The films were characterized with Auger spectroscopy, x-ray diffraction, self-inductance and four-probe resistance techniques. We have found an interesting interaction between deposition rate, substrate topography and target oxygenation in the determination of film quality. The best films are produced with dense underoxygenated targets at low laser repetition rates (1 Hz) on very smooth substrates; the optimal deposition parameters for these are given. Atomic force microscopy shows spiral growth formations with a unit-cell edge height. Oriented outgrowths observed on some films are attributed to heat-modified substrate surface morphology. a-axis films also have been grown using PrBa2Cu3 Ox template layers. (author)