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

Abstract

Vacancy-type defects in Si-doped InN grown by plasma-assisted molecular-beam epitaxy probed using monoenergetic positron beams

Identifying vacancy complexes in compound semiconductors with positron annihilation spectroscopy: A case study of InN

“…Although V In related defect concentrations in thick layers of high-quality as-grown material are found to be low, in the 10 16 cm −3 range, 17 the experimentally observed concentrations are still by orders of magnitude higher than what could be expected based on first-principles calculations. 8,12 A strong influence of the layer thickness on the vacancy concentrations has been found, 15 together with a commonly observed increase and qualitative change of the vacancy signal when approaching the layer-substrate interface.…”

“…This suggests that the vacancy formation in InN is not dominated by thermal equilibrium processes but rather controlled by mechanisms such as local strain, the vicinity to other point and extended defects, and/or limited surface diffusion during growth. 17 Nevertheless, to the best of our knowledge, no direct correlation between dislocation densities and vacancy formation has been found so far. 17,20 In good agreement with the behavior of negatively charged defects below the branch point energy, 1,21 n-type doping of InN by either Si (Refs.…”

“…17 Nevertheless, to the best of our knowledge, no direct correlation between dislocation densities and vacancy formation has been found so far. 17,20 In good agreement with the behavior of negatively charged defects below the branch point energy, 1,21 n-type doping of InN by either Si (Refs. 19 and 22) or high-energy particle irradiation 6 leads to an increasing incorporation of V In related defects, while Mg-doped samples (with lowered Fermi-level positions) show only low concentrations.…”

“…8,12 A strong influence of the layer thickness on the vacancy concentrations has been found, 15 together with a commonly observed increase and qualitative change of the vacancy signal when approaching the layer-substrate interface. 7,15,18,19 Growth parameters such as polarity 7 and stoichiometry 17,18 seem to have only a minor impact. This suggests that the vacancy formation in InN is not dominated by thermal equilibrium processes but rather controlled by mechanisms such as local strain, the vicinity to other point and extended defects, and/or limited surface diffusion during growth.…”

“…While direct experimental evidence on the behavior of V N has been very limited, previous positron annihilation results show that V In related defects are incorporated in concentrations of ∼10 16 -10 17 cm −3 during growth of both molecular beam epitaxy (MBE) [15][16][17] and metalorganic chemical vapor deposition (MOCVD) 18 InN. Although V In related defect concentrations in thick layers of high-quality as-grown material are found to be low, in the 10 16 cm −3 range, 17 the experimentally observed concentrations are still by orders of magnitude higher than what could be expected based on first-principles calculations.…”