• In2O3;
  • epitaxy;
  • antiphase domains;
  • rotation domains;
  • group theory;
  • transmission electron microscopy

In2O3 is important because it has been widely used as a transparent contact material and an active gas sensor material. To understand and utilize its intrinsic physics as a semiconductor, it is necessary to have In2O3 with a high material quality. In this article, single-crystalline (001)-oriented In2O3 thin films were grown on yttria-stabilized zirconia (001) substrate, and a group theory analysis and transmission electron microscopy (TEM) experiments were conducted to investigate the defects within the In2O3 film. Owing to the reduced symmetry of the bixbyite structure (space group inline image) in comparison with the fluorite template (space group inline image), the formation of antiphase domains and 90° rotation domains in the In2O3 thin films is anticipated. This prediction is confirmed experimentally by TEM and high-angle annular dark-field scanning transmission electron microscopy images. The size of the enclosed domains ranges from 50 to 300 nm, and the major domain boundaries are along the (110), (inline image), (010) and (100) planes. The rotation domains are related by a fourfold rotation operation along the 〈001〉 directions, which will cause the permutation of the axes of the bixbyite structure.