The effects of substrate thermal mismatch on the domain structure of mocvd-derived potassim niobate thin films

摘要

Domain stabilization in epitaxial potassium niobate films deposited by metalorganic chemical vapor deposition was studied. Stabilization was examined for films deposited on substrates swith different coefficients of thermal expansion. X-ray diffraction of KNbO_3 films deposited on (100) MgAl_2O_4, (r)Al_2O_3, and (100)_pseudocubic YAlO_3 substrates shows a mixed domain structure consistingof (110) and (001) domains. However, KNbO_3 thin films deposited under identical conditions on (100)MgO, (100)SrTiO_3, and (100)_pseudocubic LaAlO_3 substrates exhibited only a single domain variant. A direct correlation between (001) domain volume fraction in the as-deposited KNbO_3 films and calculated strain resulting from thermal mismatch is observed.