Sm-doped BaTiO ₃ thin films with ~200 nm thickness fabricated by rf magnetron sputtering system onto Pt/Ti/SiO ₂/ Si substrates have been investigated. The effects of postannealing and the dopant content in a range of 0.1 to 2.2 at.% on microstructure and electrical properties were studied. The films were found to be amorphous in the as-deposited state and became fully crystallized after annealing at 750°C and above. The addition of Sm in the BaTiO ₃ films resulted in the inhibition of grain growth. Electrical characterizations show that the dielectric permittivity increased with increasing annealing temperatures and the 2.2% Sm-doped film had the low leakage current of 1.29×10^-9 A at an applied electric field of 100 KV/cm.