Defects in LPE-grown β-barium borate (β-BaB2O4) thin films

Morphological defects in β-barium borate (β-BBO) thin films grown on Sr2+-doped α-BBO substrates by liquid phase epitaxy (LPE) technique were studied by scanning electron micrograph (SEM), atomic force microscopy (AFM) and optical spectroscopy. The present results indicate that the main defects exit in β-BBO thin films are microcracks and hollow structure. The formation of microcrack is due to the lattice mismatch and the difference of thermal expansion coefficients between substrate and film. The hollow structure might be caused during the combination of islands, which formed in the initial stage.