Effect of composition and microstructure on temperature coefficient of resistance of polycrystalline La1-xCaxMnO3 thin films

Polycrystalline La1-xCaxMnO3 films were rf-sputtered on Si substrates coate d with SiO2, and the effects of deposition parameters on the temperature co efficient of resistance (TCR) values were investigated. For the temperature higher than the metal-insulator transition temperature (T-p), the temperat ure dependence of resistance can be described by using the small polaron mo del, and the TCR value increases with the activation energy E-a for the pol aron hopping. For the temperature higher than TP I increasing the oxygen or Ca content of the film results in the decrease in resistivity, E-a, and TC R value. The resistivity and TCR value are also reduced in large-grained fi lms. Applying a substrate bias can enhance the TCR value. (C) 2001 American Vacuum Society.