Effect of sputtering pressure on growth behavior of heteroepitaxial ZnO/SrTiO3 (001) films grown by radio frequency magnetron sputtering

The effect of sputtering pressure on the growth behavior of heteroepitaxial ZnO films grown by radio-frequency magnetron sputtering on SrTiO3 (STO) (001) substrates was investigated. Columnar growth of ZnO films at a growth pressure of 3×10−2 Torr was observed, while typical planar growth was dominant at lower growth pressures. This can be explained by the complicated interplay between the surface diffusivity of ZnO films and their growth rates. We also found that wurtzite hexagonal ZnO films with a preferred (0002) orientation could be grown epitaxially on the perovskite cubic STO (001) substrates in the substrate normal direction. Azimuthal angle scans of off-specular ZnO (101¯1) Bragg peaks revealed that the domains of ZnO films tilted by ±15° with respect to the STO [100] direction in the in-plane direction. The epitaxial relationship was confirmed as being ZnO[101¯0]//STO [110] and ZnO [101¯0]//STO [1¯10].

► The effect of sputtering pressure on the growth behavior of heteroepitaxial ZnO films grown by radio-frequency magnetron sputtering on SrTiO3 (STO) (001) substrates was investigated.
► Columnar growth of ZnO films at a growth pressure of 3×10−2 Torr was observed, which can be explained by the complicated interplay between the surface diffusivity of ZnO films and their growth rates.
► The domains of ZnO films tilted by ±15° with respect to the STO [100] direction in the in-plane direction. The epitaxial relationship was confirmed as being ZnO[101¯0]//STO[110] and ZnO[101¯0]//STO[1¯10].