Influence of V/III molar ratio on the formation of In vacancies in InN grown by metal-organic vapor-phase epitaxy

Pelli, A.; Saarinen, K.; Tuomisto, Filip; Ruffenach, Sandra; Briot, Olivier

doi:10.1063/1.2219335

Cited by 32 publications

(40 citation statements)

References 14 publications

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“…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.…”

Section: Introductionmentioning

confidence: 99%

“…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.…”

Section: Introductionmentioning

confidence: 99%

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

2011

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We present a comprehensive study of vacancy and vacancy-impurity complexes in InN combining positron annihilation spectroscopy and ab initio calculations. Positron densities and annihilation characteristics of common vacancy-type defects are calculated using density functional theory, and the feasibility of their experimental detection and distinction with positron annihilation methods is discussed. The computational results are compared to positron lifetime and conventional as well as coincidence Doppler broadening measurements of several representative InN samples. The particular dominant vacancy-type positron traps are identified and their characteristic positron lifetimes, Doppler ratio curves, and line-shape parameters determined. We find that indium vacancies (V In ) and their complexes with nitrogen vacancies (V N ) or impurities act as efficient positron traps, inducing distinct changes in the annihilation parameters compared to the InN lattice. Neutral or positively charged V N and pure V N complexes, on the other hand, do not trap positrons. The predominantly introduced positron trap in irradiated InN is identified as the isolated V In , while in as-grown InN layers V In do not occur isolated but complexed with one or more V N . The number of V N per V In in these complexes is found to increase from the near-surface region toward the layer-substrate interface.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

2011

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“…11 The InN sample irradiated to the fluence of 5 ϫ 10 13 cm −2 exhibited a slightly lower S parameter than the previously used InN reference. 12,13 We interpret this to originate from the greater thickness of the current sample ͑2.7 m͒ since in the same work the quality of the MBE-grown InN is known to improve with increasing layer thickness. In addition, as shown below, the vacancy concentration produced in InN with this fluence should be below the detection limit of the positron method at room temperature.…”

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confidence: 99%

Compensating point defects inHe+4-irradiated InN

Tuomisto

Pelli

et al. 2007

Phys. Rev. B

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We use positron annihilation spectroscopy to study 2 MeV 4 He + -irradiated InN grown by molecular-beam epitaxy and GaN grown by metal-organic chemical-vapor deposition. In GaN, the Ga vacancies act as important compensating centers in the irradiated material, introduced at a rate of 3600 cm −1 . The In vacancies are introduced at a significantly lower rate of 100 cm −1 , making them negligible in the compensation of the irradiation-induced additional n-type conductivity in InN. On the other hand, negative non-open volume defects are introduced at a rate higher than 2000 cm −1 . These defects are tentatively attributed to interstitial nitrogen and may ultimately limit the free-electron concentration at high irradiation fluences.

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“…1. Interestingly, also in MOCVD growth of InN, 8 vacancy clusters appear in the In-droplet regime. Another observable difference between the N-and In-polar samples ͑both grown on MBE-GaN͒ is that the vacancy concentrations are generally slightly larger in the N-polar films.…”

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confidence: 99%

“…[7][8][9] High In vacancy concentrations have been observed to coexist with high free electron densities and low electron mobilities in MBE-InN, 7 while their formation has been found to be independent of growth stoichiometry, but dependent on growth temperature, in MOCVD-InN. 8 In this letter, we show that the in-grown In vacancy concentrations ͓V In ͔ even in high quality ͑low carrier density, high mobility͒ MBE-InN are much higher than could be expected from the predicted formation energy and that there is no clear correlation between ͓V In ͔ and growth conditions, impurity content, or dislocation densities. Hence, in high quality InN, the electron mobility is likely limited not by ionized point defect scattering.…”

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confidence: 99%