Growth mode issues in epitaxy of complex oxide thin films

Abstract

We discuss the hetero-epitaxy of complex oxides taking YBa2Cu3O7-δ as an example. Special emphasis is on films grown by pulsed laser deposition (PLD), but other growth techniques are also discussed. Lattice mismatch in three directions is responsible for the fact that a real single crystalline YBa2Cu3O7-δ thin film has not yet been obtained. Nevertheless, growth features typically observed on single crystals (e.g. growth spirals as well as repeated nucleation and growth) are often found on YBa2Cu3O7-δ thin films. We discuss how surface diffusion and supersaturation influence the surface morphology (as observed by atomic force and scanning tunnelling microcopies (AFM/STM)) of complex oxide thin films. In particular, we conclude that the kinetic energy of the impinging adatoms affects the surface diffusivity and therefore the growth mode.