High Resolution X-Ray Diffraction Analyses of (La,Sr)MnO 3 /ZnO/Sapphire(0001) Double Heteroepitaxial Films

Abstract

Thin films of (La,Sr)MnO 3 (LSMO) were deposited on ZnO underlayer on sapphire (Sap) substrate by ion beam sput-tering at the growth temperatures from 650˚C to 750˚C with supply of either plasma oxygen or molecular oxygen. The epitaxial relationships of lattices and crystalline qualities of LSMO/ZnO/Sap double-hetero systems were extensively analyzed by means of X-ray diffraction techniques with a modern high resolution XRD system. The epitaxial growth of out-of-plane (110) phase of the LSMO overlayer on the (0001) ZnO underlayer on the (0001) sapphire substrate is promoted at the higher temperatures accompanying the suppression of other competitive growth of the LSMO (001) and (111) phases. The plasma oxygen supply more enhances this suppression of the LSMO (111) phase at 750˚C. The com-plex in-plane orientational relationships of these three phases were clarified by the precise analyses based on various measurements of high resolution out-of-plane XRD and in-plane XRD, pole figure, and reciprocal space mappings. They are summarized as follows. [110](110)LSMO / /[1100](0001)ZnO / /[1120](0001)Sap , [110](001)LSMO / /[1100](0001)ZnO / /[1120](0001)Sap , and [112](111)LSMO / /[1100](0001)ZnO / /[1120](0001)Sap (μ-mode), where the notations such as [110] indicate the in-plane crystalline directions. The two possible configurations of LSMO (111) phase were discussed. These relation-ships were confirmed also by the data analyses of out-of-plane wide-range reciprocal space mappings using the 2-di-mensional X-ray detector.