Tailoring the in-plane epitaxial relationship of InN films on (1 1 1)SrTiO3 substrates by substrate pretreatment

Abstract

Wurtzite InN films of c-axis orientation have been grown on as-received and water-immersed (111)SrTiO3 (STO) substrates by metal–organic chemical vapor deposition. The epitaxial relationships between InN films and STO substrates are investigated by X-ray diffraction. Two kinds of in-plane alignment of [112¯0]InN∥[11¯0]STO and [11¯00]InN∥[11¯0]STO with a 30° rotation relative to each other have been realized on as-received and water-immersed (111)STO substrates, respectively. The in-plane orientation of InN relative to STO is strongly dependent on substrate pretreatment, but not sensitive to growth temperature and trimethylindium flow rates. The difference in terminated surfaces of as-received and water-immersed STO substrates are postulated to be responsible for the change in epitaxial relationships. Compared with each other, the in-plane epitaxial relationships of [11¯00]InN∥[11¯0]STO and [112¯0]InN∥[11¯0]STO are respectively energetically preferred due to a higher bonded density and thus a lower interface energy on SrO3- and Ti-terminated STO substrates.