Buckeridge<i>et al.</i>Reply:

Buckeridge, John; Catlow, C. Richard A.; Scanlon, David O.; Keal, Thomas W.; Sherwood, Paul; Miskufova, M.; Walsh, Aron; Woodley, Scott M.; Sokol, Alexey A.

doi:10.1103/physrevlett.115.029702

Cited by 31 publications

(60 citation statements)

References 6 publications

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“…The properties of Mg acceptors in GaN have also been calculated using an embedded cluster method (). In this approach, a small region treated with quantum mechanical methods is surrounded by a much larger region treated with interatomic potentials.…”

Section: Acceptor Impurities In Ganmentioning

confidence: 99%

First‐principles theory of acceptors in nitride semiconductors

Lyons

Alkauskas

Janotti

et al. 2015

Physica Status Solidi (b)

127

107

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Acceptor defects and impurities play a critical role in the performance of GaN-based devices. Mg is the only acceptor impurity that gives rise to p-type conductivity, while other acceptors (such as C N impurities and V Ga defects) act as sources of compensation and trapping. From the point of view of theory, understanding the physics of acceptor species in GaN has long been a challenge. In the past, limitations of computational techniques made it difficult to quantitatively predict crucial quantities such as thermodynamic and optical transition levels. However, advances in first-principles calculations, including the use of hybrid functionals in density functional theory, have led to a resurgence in efforts to understand properties of acceptors in nitrides. After briefly discussing advances in theoretical techniques, we review recent computational work on acceptor impurities in GaN and compare theoretical results with the available experimental data. We also present new hybrid density functional calculations on the transition levels of V Ga and its complexes with O and H impurities. The results indicate that donor impurities significantly lower V Ga transition levels, and that V Ga -3H and V Ga -O N -2H complexes give rise to yellow luminescence. We also discuss the properties of acceptor impurities in AlN and InN.

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Section: Acceptor Impurities In Ganmentioning

confidence: 99%

First‐principles theory of acceptors in nitride semiconductors

Lyons

Alkauskas

Janotti

et al. 2015

Physica Status Solidi (b)

127

107

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“…Reboredo and Pantelides stated that "interstitial Mg plays a major role in limiting p-type doping" [9,10]. The failure of experimental methods in establishing the existence of interstitial Mg and investigating its properties probably contributed to the fact that in the following years many researchers adopted the opinion that the doping limitations at high Mg concentrations are, in addition to passivation by H [8,11], mostly a consequence of native defects with donor character, in particular N vacancies V N , either in their isolated form [12,13] or in Mg Ga -V N complexes with Mg [14,15].…”

mentioning

confidence: 99%

“…[23] for details). Besides an attempt frequency ν 0 , for which we have taken 2×10 13 Hz, corresponding to the 657 cm −1 local mode assigned to Mg in GaN [38], N was assumed ranging from 1 to 10 5 , where N=1 represents the limiting case in which the Mg i has a neighboring Ga vacancy, and N=10 5 is the upper limit when the diffusion-induced widening of the Mg i profile becomes comparable to the implantation depth, which can be excluded since it would considerably deteriorate the channeling effects. According to the least square fits shown by the solid lines in Fig.…”

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confidence: 99%

Lattice Location of Mg in GaN: A Fresh Look at Doping Limitations

et al. 2017

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Radioactive27 Mg (t 1/2 =9.5 min) was implanted into GaN of different doping types at CERN's ISOLDE facility and its lattice site determined via β − emission channeling. Following implantations between room temperature and 800°C, the majority of 27 Mg occupies the substitutional Ga sites, however, below 350°C significant fractions were also found on interstitial positions ~0.6 Å from ideal octahedral sites. The interstitial fraction of Mg was correlated with the GaN doping character, being highest (up to 31%) in samples doped p-type with 2×1019 cm −3 stable Mg during epilayer growth, and lowest in Si-doped n-GaN, thus giving direct evidence for the amphoteric character of Mg. Implanting above 350°C converts interstitial 27 Mg to substitutional Ga sites, which allows estimating the activation energy for migration of interstitial Mg as between 1.3 and 2.0 eV.

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“…3 Since then, both calculations and electron irradiation measurements have shown that N-vacancies for charged states that were previously not considered do indeed exist with reasonable formation energies, with donor levels in the range of 44 meV to 70 meV. 33,34 In Ref. 35, evaporation of N from the GaN growth front is demonstrated and discussed.…”

Section: à3mentioning

confidence: 98%

Investigation of Si and O Donor Impurities in Unintentionally Doped MBE-Grown GaN on SiC(0001) Substrate

Tingberg

Ive

Larsson

2017

Journal of Elec Materi

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We have investigated the unintentional n-type background doping in GaN(0001) layers grown on semi-insulating 4H-SiC(0001) substrate by plasma-assisted molecular beam epitaxy under Ga-rich conditions at growth temperatures from 780°C and 900°C. All layers exhibited very smooth surface morphology with monolayer steps as revealed by atomic force microscopy. Hall-effect measurements showed that the sample grown at 900°C had carrier concentration of 9.8 9 10 17 cm À3 while the sample grown at 780°C had resistivity too high to obtain reliable measurements. Secondary-ion mass spectroscopy revealed O and Si concentrations of <10 17 cm À3 in the sample grown at 900°C but >10 17 cm À3 in the sample grown at 780°C. The trend for the atomic concentrations of O and Si, which are common donor impurities in GaN, was thus contrary to the trend of the carrier concentration. The fullwidth at half-maximum for x-ray rocking curves obtained across the GaN(0002) and GaN(10 15) reflections for the sample grown at 900°C was 62 arcsec and 587 arcsec, respectively. The half-width increased with decreasing growth temperature. The atomic concentrations of O and Si are too low to account for the unintentional background doping levels. A possible explanation proposed in early reports for the background doping is N-vacancies.

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Buckeridgeet al.Reply:

Cited by 31 publications

References 6 publications

First‐principles theory of acceptors in nitride semiconductors

First‐principles theory of acceptors in nitride semiconductors

Lattice Location of Mg in GaN: A Fresh Look at Doping Limitations

Investigation of Si and O Donor Impurities in Unintentionally Doped MBE-Grown GaN on SiC(0001) Substrate

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