Thermal stability of amorphous Zn-In-Sn-O films

Isochronal annealing of amorphous Zn and Sn codoped In₂O₃ (a-ZITO) films was performed at the Synchrotron so that to extract, in situ, important kinetic nucleation and growth parameters from a single constant-rate heating experiment. First, amorphous Zn and Sn codoped In₂O₃ films were deposited via pulsed laser deposition and subjected to post-deposition annealing treatments to study their stability against crystallization. Crystallization on glass and ĉ-sapphire occurred near the same temperature, however higher codoping levels resulted in increased crystallization temperatures. Post-deposition anneal crystallization temperatures were found to be higher than the substrate temperatures required to grow crystalline films during deposition. Then, a-ZITO films were subjected to a constant temperature ramp during in situ grazing-incidence X-ray diffraction experiments. Crystallization of films on both glass and ĉ-sapphire showed similar gradual crystallization behavior between 300 and 345 °C and strong (111) texturing, which suggests the influence of surface energy minimization during crystallization. The activation energy was found to be 2.87 eV using Johnson-Mehl-Avrami analysis. This work presents the advantages of in situ experiments to study nucleation and growth during crystallization of transparent conducting oxides.