Structural analysis of cubic InN films grown by molecular beam epitaxy

Abstract

In the thesis, the structural modification and crystal quality of the cubic InN (c-InN) films grown on (001) substrates by molecular beam epitaxy have been systematically investigated and analyzed. The effects of the growth conditions, namely In- and N-rich conditions, and the buffer layer are established. Based on high-resolution X-ray diffraction and Raman scattering measurements, we found that the InN films used in this study have a cubic structure and contain some amount of hexagonal phase subdomains tilted from the (001) plane. These results confirm that the hexagonal phase is generated on the cubic {111} planes and becomes dominance in the c-InN films grown under the N-rich growth condition. In contrast, the films with higher crystal quality and lower hexagonal phase inclusion were grown under the In-rich growth condition. Furthermore, we also found that, with using c-GaN as a buffer layer, the hexagonal phase presented in the buffer layer greatly influences the hexagonal phase generation and crystal quality of the c-InN upper films. This result suggests that the buffer layer with lower hexagonal phase incorporation is suitable for growing the c-InN layers with high crystal quality and high cubic-phase purity. These results demonstrate that the In-rich growth condition and the crystal quality of the buffer layer play an important role in growing high cubic-phase purity c-InN films without generation of hexagonal phase structure.