Crystallization of sputtered BaTiO3-based thin films:: A differential scanning calorimetry study

Crystallization behavior of sputtered BaTiO3 and Nb-doped BaTiO3 thin films has been characterized by means of the differential scanning calorimetry (DSC). The crystallization of as-deposited amorphous structure to the equilibrium crystalline structure is confirmed as an irreversible, exothermic, first-order transition. Our in situ DSC result confirming the metastable nature of sputtered films is in agreement with that of a conventional, ex situ x-ray diffraction result. At a heating rate of 20 degreesC/min, the crystallization peak temperature of BaTiO3 film is found to be 467.6 degreesC and to increase with the addition of Nb. Activation energies for crystallization are determined by Kissinger's method to be 139.2, 99.3, and 81.0 kJ/mol for pure BaTiO3, BaTiO3-2 at. % Nb, and BaTiO3-3 at. % Nb films, respectively. The decrease in activation energy suggests the addition of Nb tends to assist the thermal-activated crystallization process in sputtered films. (C) 2000 American Institute of Physics. [S0021-8979(00)07023-7].