Vacancy defects probed with positron annihilation spectroscopy in In-polar InN grown by plasma-assisted molecular beam epitaxy: Effects of growth conditions

In this work we have applied positron annihilation spectroscopy to study the effect of different growth conditions, on vacancy formation in In-polar InN grown by plasma-assisted molecular beam epitaxy (PA-MBE). We find that the stoichiometric conditions have little effect on the In vacancy concentration in the thin films. On the other hand, the optimization of the GaN buffer used for initiating InN growth leads to a lower In vacancy concentration. This indicates that the structural quality of the material dictates the In vacancy formation in InN, while the thermodynamic and kinetic effects have a less important role, contrary to what is observed in, e.g., GaN.