Microstructural evolution and electrical properties of La_(0.7)Ca_(0.3)MnO_3 thin films grown on SrTiO_3 substrates by excimer-laser assisted metal-organic deposition

摘要

Thin films of La_(0.7)Ca_(0.3)MnO_3 were successfully grown epitaxially on (100) single-crystal SrTiO_3 substrates by excimer-laser assisted metal-organic deposition. Initial amorphous LCMO thin films were obtained by metal-organic deposition at 500℃. Crystallization and epitaxial growth of the films was achieved using a KrF pulsed laser irradiation while the film/substrate samples were kept at 500℃. High resolution transmission electron microscopy observations on cross-sections demonstrate the formation mechanism of the epitaxial films. The crystallization process starts at the LCMO/STO interface and grows by increasing the number of laser shots. A fully crystallized film was obtained after 5 min of irradiation. The film/substrate interface was found to be sharp and abrupt. The temperature dependence of the resistance R(T) shows various behaviors, starting from insulating to semiconducting and metal-insulator transition material during the formation of the manganite film. The oxygen content was also improved by increasing the irradiation time. Promising values of the temperature coefficient of resistance were obtained from these manganite films for prospect integration in silicon based mi-crobolometric devices.