Growth and structure properties of La_(1-x)Sr_xMnO_(3-δ) (x=0.2, 0.3, 0.45) thin film grown on SrTiO_3 (001) single-crystal substrate by laser molecular beam epitaxy

摘要

La_(1-x)Sr_xMnO_(3-δ) (LSMO) thin films have been grown on SrTiO_3 (001) single-crystal substrates using the laser molecular beam epitaxy (MBE) technique. The two-dimensional layer-by-layer growth was in-situ monitored by reflection high-energy electron diffraction (RHEED). Kinetic growth with surface relaxation was also observed, and crystallinity of the thin films was investigated by high-resolution X-ray diffraction. Results of 2θ-ω scans revealed a strong correlation between out-of-plane lattice constant and oxygen content as well as strontium doping concentration. However, further analysis of rocking curve measurements around (0 02) plane of thin films grown under different oxygen pressure (P_(O2)) shown the effects of oxygen content on the crystal structure. An exceptionally low full-width at half-maximum (FWHM) of 0.02° was measured from the sample grown at P_(O2) of 5.0 Pa, indicating the almost perfect epitaxial growth of LSMO thin films.