Sr-diffusion-induced inhibition of (100)-oriented growth Ca1−xSrxVO3 thin film on a LaAlO3 substrate in pulsed laser deposition

Abstract

Ca0.5 Sr0.5VO3 (CSVO) thin films were fabricated on LaAlO3 (LAO) and SrTiO3 (STO) substrates using pulsed laser deposition. The lattice mismatch between the CSVO and the substrates is +2.6% for STO and −0.4% for LAO, suggesting that LAO should be more appropriate for crystallization. However, the obtained results were not what was expected. While the CSVO on the STO substrate was highly oriented in (100) direction, the one on the LAO substrate was amorphous and a metal-insulator transition was absent from the electrical characteristics. Although the results clearly showed that STO is more suitable for CSVO deposition, this behavior is not explained merely by the lattice mismatch. Energy dispersive X-ray spectroscopy measurements revealed that Sr diffused from the CSVO thin film into the LAO substrate, which induced a large deviation in the chemical composition of the CSVO thin film. The results display evidence that the low quality of CSVO thin films on LAO is caused by Sr diffusion.