Structural analysis of pyramidal defects in Mg‐doped GaN

Pretorius, A.; Schowalter, Marco; Daneu, Nina; Kröger, Roland; Rečnik, Aleksander; Rosenauer, A.

doi:10.1002/pssc.200565259

Cited by 7 publications

(9 citation statements)

References 12 publications

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“…However, with increasing Mg dopant concentration, non-substitutional sites are progressively occupied. Using a two-position model, an additional Mg incorporation site was identified that agrees well with a local anti-bixbyite-like structure that has been proposed earlier [16,17] to occur at inversion domain boundaries.…”

Section: Si Doped Filmsmentioning

confidence: 68%

“…11, an according model is presented that can explain the XSW results by Mg enrichment at inversion domain boundaries. The atomic arrangement in this model resembles the anti-bixbyite structure, in agreement with the structure of basal inversion domain boundaries at pyramidal defects as determined from TEM analyses [16,17]. Here, Mg is assumed to occupy both Ga substitutional sites (lower Mg layer in Fig.…”

Section: Incorporation and Defects 41 Mg Doped Filmsmentioning

confidence: 73%

“…For large Mg concentrations, however, high densities of extended defects have been reported, such as Mg induced pyramidal defects [10][11][12], extended facetted defects [5,13,14], and nanotubes [15]. A common building blocks of all these defects is given by inversion domain boundaries [14,[16][17][18] where Mg is agglomerated, leading to a decrease of the hole concentration. It has been proposed that such defects arise from Mg surface segregation and they form as soon as a the local Mg concentration near the surface exceeds a certain threshold concentration [12].…”

Section: â 10mentioning

confidence: 99%

“…All these defects include inversion domain boundaries with local Mg enrichment [14,[16][17][18]. A cross-sectional transmission electron micrograph of one of the samples investigated with XSW is shown in Fig.…”

Section: Incorporation and Defects 41 Mg Doped Filmsmentioning

confidence: 99%

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Mg and Si dopant incorporation and segregation in GaN

Schmidt

Siebert

Flege

et al. 2011

Physica Status Solidi (b)

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The surface segregation of Mg and Si dopant species and their atomic incorporation sites in GaN films grown by metal-organic vapour phase epitaxy (MOVPE) on sapphire (0001) substrates have been analysed by X-ray photoemission spectro-microscopy and X-ray standing waves (XSW). As revealed by spectro-microscopy, both Mg and Si tend to segregate to the surface. In case of Mg, an enhanced surface dopant concentration is found even after sputter-removal of several tens of nanometres, which confirms a segregation mechanism proposed earlier [S. Figge et al., Appl. Phys. Lett. 81, 4748 (2002)]. Si doping has been found to result in the formation of facetted grooves in the GaN films. The surface silicon concentration at the facets is determined to be about 2.5 times higher as compared to the planar (0001) surface by micro-spectroscopy. XSW results show that with increasing Mg dopant concentration, non-substitutional lattice sites are progressively occupied. The results can quantitatively be explained by Mg atoms incorporated in an anti-bixbyite-like structure and is related to inversion domain boundaries. For Si doping, no evidence is found for the occupation of non-substitutional sites. However, a decrease in crystal quality is observed with increasing Si concentration.X-ray photoemission micrograph of a Si doped GaN film showing a facetted groove at the lower left corner of the image. The local spectra (see inset) reveal Si enrichment at the facets.

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Section: Si Doped Filmsmentioning

confidence: 68%

Section: Incorporation and Defects 41 Mg Doped Filmsmentioning

confidence: 73%

Section: â 10mentioning

confidence: 99%

Section: Incorporation and Defects 41 Mg Doped Filmsmentioning

confidence: 99%

See 2 more Smart Citations

Mg and Si dopant incorporation and segregation in GaN

Schmidt

Siebert

Flege

et al. 2011

Physica Status Solidi (b)

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“…2a. The layer thickness of 1.9-2.7 nm and the In concentration of 0.22±0.03 were derived from the results of TEM observations [8]. When the layer was grown for 35 s, the nano-islands were observed, as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Two to three dimensional transitions of InGaN and the impact of GaN overgrowth

Yamaguchi

Einfeldt

Gangopadhyay

et al. 2006

Phys. Status Solidi (c)

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The heteroepitaxial growth of InGaN on GaN was studied by in-situ reflection high-energy electron diffraction, atomic force microscopy, scanning tunneling microscopy and transmission electron microscopy. The misfit strain between InGaN and GaN was relaxed by the deposition of a few-nm-thick wetting layer and the subsequent formation of nano-islands without misfit dislocations, which is the so-called StranskiKrastanov growth mode. Thus, InGaN nano-islands with a very high density of around 10 12 cm -2 and a very small aspect ratio of ~2.1 (diameter/height) were achieved. In this paper, we also discuss the problems regarding GaN overgrowth of an InGaN nano-island layer.

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GaN:-Mg grown by MOVPE: Structural properties and their effect on the electronic and optical behavior

Simbrunner

Wegscheider

et al. 2008

Journal of Crystal Growth

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The effect of Mg δ-doping on the structural, electrical and optical properties of GaN grown via metalorganic vapor phase epitaxy has been studied using transmission electron microscopy, secondary ion mass spectroscopy, atomic force microscopy, x-ray diffraction, Hall effect measurements and photoluminescence. For an average Mg concentration above 2.14 × 10 19 cm −3 , phase segregation occurs, as indicated by the presence of Mg-rich pyramidal inversion domains in the layers. We show that δ-doping promotes, in comparison to Mg continuous doping, the suppression of extended defects on the samples surface and improves significantly the morphology of the epilayers. Conversely, we can not confirm the reduction in the threading dislocation density -as a result of δ-doping -reported by other authors. In the phase separation regime, the hole concentration is reduced with increasing Mg concentration, due to self-compensation mechanisms. Below the solubility limit of Mg into GaN at our growth conditions, potential fluctuations result in a red-shift of the emission energy of the free-to-bound transition.

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Structural analysis of pyramidal defects in Mg‐doped GaN

Cited by 7 publications

References 12 publications

Mg and Si dopant incorporation and segregation in GaN

Mg and Si dopant incorporation and segregation in GaN

Two to three dimensional transitions of InGaN and the impact of GaN overgrowth

GaN:-Mg grown by MOVPE: Structural properties and their effect on the electronic and optical behavior

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