ＬｉＮｂＯ３のエピタキシャル成長に及ぼす界面エネルギーの影響

Abstract

To investigate the effect of interfacial energy on the epitaxial growth of LiNbO3, liNbO3, was deposited on the (001) α-Al2O3 by a rf magnetron sputtering using pressed powder targets to decrease the deposition rate. Below the substrate temperature of 650°C, only the LiNb3O8 (-602) layer grew epitaxially at the same deposition conditions as the LiNbO3 (012) growing epitaxially on the α-Al2O3 (012) single crystal substrate. The reason is that the interfacial energy at the LiNb3O9, (-602)/ α-Al2O3 (001) interface is smaller than that at the LiNbO3 (001) / α-Al2O3 (001) interface. Therefore, even under the conditions to deposit films with the higher Li concentration by increasing the Li/Nb ratio in the targets, the LiNbO3 layer did not grow, but the LiNb3O8 (-602) epitaxial layer grew. However, above the substrate temperature of 700°C, a mixtured layer of LiNbO3 and LiNb3O8 grew. By using the target with the highest Li/ Nb ratio (3/1), the epitaxial layer of LiNbO3(001) grew, though contained the thin mixtured layer of LiNbO3 and LilNb3O8 polycrystallines at the surface. The polycrystalline layer transformed to the epitaxial LiNbO3 layer by annealing at 800°C in the oxygen gas atmosphere.