Hetero-epitaxial Growth of Cubic La(Sr)MnO₃ on Hexagonal ZnO, In-Plane Orientations of La(Sr)MnO₃ (001), (110), and (111) Phases

Abstract

Hexagonal ZnO was grown on a hexagonal (001) sapphire substrate. Then cubic La(Sr)MnO3 (LSMO) was grown on a ZnO underlayer by ion beam sputtering at various substrate temperatures to obtain double-layers of LSMO/ZnO and to investigate hetero-epitaxial orientation growth. Out-of-plane (001)-oriented ZnO was grown with an in-plane orientation of [101̄0](001)ZnO ∥ [112̄0](001)sapphire (B-mode). Three phases of LSMO with out-of-plane (001), (110), and (111) orientations were grown on (001) ZnO generally. However, each single phase of LSMO could be grown only by controlling the deposition conditions. We achieved the in-plane orientation growth of LSMO, [110](001)LSMO ∥ [101̄0](001)ZnO (B-mode), [11̄0](110)LSMO ∥ [101̄0](001)ZnO (A-mode), and [11̄0](111)LSMO ∥ [112̄0](001)ZnO (B-mode). The A-mode is defined as the mode in which both in-plane fundamental axes are parallel. The B-mode entails no parallel axes. The LSMO(001)- and (110)-grains have three equivalent in-plane domains, and the LSMO(111)-grain has a single domain. Lattice matching calculation can be used to partially interpret the orientation growth.

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

“…Probably the LSMO (110) phase has the better lattice matching at the higher temperatures, while the LSMO (001) phase has the better lattice matching at the lower temperature due to different thermal expansion rates of these lattices. It was partially reported by our previous paper [4]. However, the LSMO (111) phase behaves curiously.…”

“…Deposition conditions for the LSMO overlayer were varied as a function of the substrate temperature (Ts: 650˚C -750˚C) and the oxygen partial pressure (Po). Details of the film fabrication can be referred in the previous papers [1,4].…”

Evolution of I-V Characteristics and Photo Effects of Heterojunction LBMO/ZnO Prepared by IBS

“…The ZnO thin film can be finely fabricated to show room temperature laser oscillation [3], though, it is very difficult to convert it into p-type. We tried to fabricate hetero p-n junctions of p-LBMO/n-ZnO [4,5], they should show optical, temperature and magnetic modulations of p-n characteristics because of CMR and DEC model. It must be difficult but interesting to clarify how the phase transition and phase separation act on this p-n characteristics.…”

Heteroepitaxial (111) ZnGa2O4 Thin Films Grown on (00.1) Sapphire by Pulsed Laser Deposition

“…[14,15,17] Typically, epitaxial interfaces can easily form between cubic (111) and hexagonal (00.1) crystal planes due to the crystal symmetry. [29][30][31][32] The lattice mismatch between (111) ZnGa 2 O 4 (Ga─Ga distance is 0.299 nm, whereas O─O distance is 0.271 or 0.300 nm) and (00.1) a-Al 2 O 3 (O─O distance is 0.252 or 0.286 nm) is about 5-8%, which is probably too large for a coherent interface where the mismatch is accommodated via a lattice strain. PLD is a well-known technique for growing high-quality thin films of complex metal oxides from bulk targets.…”