Comparative study of La_0.7Ca_0.18Sr_0.12MnO₃ films with room-temperature TCR grown on SrTiO₃, La_0.3Sr_0.7Al_0.65Ta_0.35O ₃ and LaAlO₃ substrates

Perovskite La-based manganites have distinctive electrical transport properties; thus, them has become a research focus because of its advanced application in room-temperature infrared bolometers. To assess the influences of different substrates on the crystallinity, surface morphology and electrical transport properties, La0.7Ca0.18Sr0.12MnO3 (LCSMO) films were grown on the (00l) SrTiO3 (STO), La0.3Sr0.7Al0.65Ta0.35O3 (LSAT) and LaAlO3 (LAO) substrates through sol-gel spin coating method. As determined by crystallinity, morphology and electrical transport properties, LCSMO/STO film with largest temperature coefficient of resistivity (TCR) were obtained compared with LCSMO/LSAT and LCSMO/LAO films. The LCSMO film grown on STO exhibited a maximum TCRmax of 9.40%/K (299.05 K), which is about 19% higher than that of the film prepared on LAO. In the LCSMO film, the electron-lattice couplings were optimized effectively owing to the low lattice mismatch between LCSMO/STO, thereby TCRmax of the film can be significantly enhanced. The results suggest that the LCSMO film grown on STO substrate possesses remarkable potential for advanced uncooled infrared bolometers.