In vacancies in InN grown by plasma-assisted molecular beam epitaxy

TL;DR

This study investigates how growth conditions affect vacancy formation in InN grown by plasma-assisted molecular beam epitaxy, revealing that structural quality and surface adatom diffusion influence vacancies, which impact electron mobility.

Contribution

It provides new insights into vacancy formation mechanisms in InN and highlights the limited role of thermodynamics compared to structural factors.

Findings

Vacancy formation is mainly influenced by structural quality and adatom diffusion.

In high-quality InN, electron mobility is limited by threading dislocations.

Growth conditions have a lesser impact on vacancy formation than previously thought.

Abstract

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. Further, 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.