Formation of Biaxially Textured MgO Buffer Layers using Ion-Beam Assisted Pulsed Laser Deposition

摘要

MgO thin films were deposited on amorphous substrates using ion-beam assisted pulsed laser deposition. The texture formation was investigated in-situ with RHEED. The microstructure of the films was observed by AFM. Using an ion beam at an angle of 55° with respect to the substrate normal, strong nucleation textures develop. Above 250℃ a cube texture is observed in films thinner than 10 nm. During further growth this nucleation texture changes in a way that the (200) direction becomes parallel to the ion beam. This change can be explained by the anisotropic sputter rate of MgO found in sputter experiments on single crystals. Moreover, MgO films were deposited homoepitaxially on MgO single crystals above 250℃ with internal stresses decreasing with increasing deposition temperature. This result gives rise to hope that homoepitaxial growth of MgO on the nucleation layer without ion-beam assistance should be possible in future PLD-experiments keeping the desired cube texture in thicker films.