Effect of Se/In flux ratio on the properties of epitaxial In2Se3 thin films

In this study, we investigated the effect of the Se/In flux ratio on the structural and optical properties of In2Se3 thin films grown on a Si(111) substrate via molecular beam epitaxy. All films were epitaxially grown at 300 °C with Se/In flux ratios of 3.6, 5, and 7. X-ray diffraction and Raman spectroscopy revealed that films grown at flux ratios of 3.6 and 7 contained a mixture of hexagonal γ- and β-In2Se3 phases, whereas the film grown at a ratio of 5 was single-phase γ-In2Se3 with improved structural uniformity and ordering. Photoluminescence measurements revealed a dominant emission peak at 1.95 eV, attributed to γ-In2Se3, with the high intensity observed for the 5-ratio sample. A secondary lower-energy peak at 1.44 eV, associated with β-In2Se3, was detected in the 3.6 and 7 ratio samples. These results demonstrate that the combined influence of the nominal Se/In supply ratio and growth kinetics plays an important role in determining phase composition, structural uniformity, and optical emission in In2Se3 thin films, providing valuable insights for phase-engineered epitaxial growth in optoelectronic applications.