The authors have applied positron annihilation spectroscopy to study the effect of different growth conditions on vacancy formation in In- and N-polar InN grown by plasma-assisted molecular beam epitaxy. The results suggest that the structural quality of the material and limited diffusion of surface adatoms during growth dictate the In vacancy formation in low electron-density undoped epitaxial InN, while growth conditions and thermodynamics have a less important role, contrary to what is observed in, e.g., GaN. Furthermore, the results imply that in high quality InN, the electron mobility is likely limited not by ionized point defect scattering, but rather by threading dislocations.
Reurings, F., Tuomisto, F., Gallinat, C. S., Koblmüller, G., & Speck, J. S. (2010). In vacancies in InN grown by plasma-assisted molecular beam epitaxy. Applied Physics Letters, 97(25), 1-3. . https://doi.org/10.1063/1.3516467