Preparation of LaFeO3 perovskite thin films by radio frequency magnetron sputtering and their electrical conductivities

La-Fe complex oxide films were prepared on Si(111), MgO(100) and SiO2 glass substrates by radio frequency magnetron sputtering using a LaFeO3 target. All the films prepared by this method have the La, Fe atomic ratio of about 1.0. The films were amorphous when the substrate temperature was lower than 650 degreesC, while orthorhombic LaFeO3-delta perovskite films were formed at the substrate temperature higher than 700 degreesC in Ar atmosphere. The orthorhombic LaFeO3-delta perovskite films were also obtained on Si(111), MgO(100) and SiO2 glass substrates by reactive sputtering in O-2/Ar = 0.2 similar to1.0 at the substrate temperature higher than 700 degreesC. However, in the case of MgO(100) substrate, the orthorhombic LaFeO3-delta perovskite film with (101) orientation was formed. The orthorhombic LaFeO3 perovskite films were formed by heat-treatment of the amorphous La-Fe complex oxide and the crystalline LaFeO3-delta perovskite films in air or O-2 atmosphere. The electrical conductivities of LaFeO3-delta/MgO(100) and LaFeO3 (delta)/SiO2 perovskite films were measured in the range from room temperature to 600 degreesC. It was found that both LaFeO3-delta/MgO(100) and LaFeO3-delta/SiO2 perovskite films are n-type semiconductors with hopping conduction in N-2, air and O-2.