Direct structural evidence of the change in N-III bonding in (GaIn)(NAs) before and after thermal annealing

Volz, Kerstin; Torunski, T.; Rubel, Oleg; Stolz, W.

doi:10.1063/1.2970162

Cited by 10 publications

(7 citation statements)

References 37 publications

(40 reference statements)

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“…Keating potentials were calculated based on the lattice constants and elastic constants in Table 1. It was shown by Müller et al (2010), Müller et al (2011), and Volz et al (2008) that the VFF relaxation is an adequate approach to consider the scattering at SADs in conventional TEM simulations of InGaNAs.…”

Section: Reference: Haadf Intensitymentioning

confidence: 99%

Simultaneous Quantification of Indium and Nitrogen Concentration in InGaNAs Using HAADF-STEM

et al. 2014

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To unambiguously evaluate the indium and nitrogen concentrations in In(x)Ga(1-x)N(y)As(1-y), two independent sources of information must be obtained experimentally. Based on high-resolution scanning transmission electron microscopy (STEM) images taken with a high-angle annular dark-field (HAADF) detector the strain state of the InGaNAs quantum well is determined as well as its characteristic HAADF-scattering intensity. The strain state is evaluated by applying elasticity theory and the HAADF intensity is used for a comparison with multislice simulations. The combination of both allows for determination of the chemical composition where the results are in accordance with X-ray diffraction measurements, three-dimensional atom probe tomography, and further transmission electron microscopy analysis. The HAADF-STEM evaluation was used to investigate the influence of As-stabilized annealing on the InGaNAs/GaAs sample. Photoluminescence measurements show an annealing-induced blue shift of the emission wavelength. The chemical analysis precludes an elemental diffusion as origin of the energy shift--instead the results are in agreement with a model based on an annealing-induced redistribution of the atomic next-neighbor configuration.

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Section: Reference: Haadf Intensitymentioning

confidence: 99%

Simultaneous Quantification of Indium and Nitrogen Concentration in InGaNAs Using HAADF-STEM

et al. 2014

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“…We were also able to show this change in the nitrogen environment upon annealing by dark field TEM recently. 21 As these results have important implications on the performance of devices which use Ga͑NAs͒ as barrier material together with ͑GaIn͒͑NAs͒ as active material, we are currently investigating annealing conditions, which result in an improvement of material quality for the quaternary alloy without deteriorating the ternary Ga͑NAs͒ barrier material.…”

Section: Resultsmentioning

confidence: 99%

Annealing effects on the nanoscale indium and nitrogen distribution in Ga(NAs) and (GaIn)(NAs) quantum wells

Volz

Torunski

Rubel

et al. 2007

Journal of Applied Physics

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III/V semiconductors containing dilute amounts of nitrogen are metastable and need to be thermally treated after growth to optimize optoelectronic properties. The influence of thermal annealing on the nitrogen depth profile in metal organic vapor phase epitaxygrown Ga͑NAs͒ / GaAs as well as ͑GaIn͒͑NAs͒ / GaAs heterostructures is examined on a nanometer scale by combining several high resolution transmission electron microscopy techniques, also with Rutherford backscattering spectrometry. Annealing conditions, which are optimized for quaternary alloys with respect to photoluminescence intensity, do not result in element redistribution for the In containing material. Contrary to the quaternary material, the result of annealing the ternary Ga͑NAs͒ is a pronounced pileup of the nitrogen profile without any out diffusion of nitrogen. These findings have important influence on device structures, which often contain Ga͑NAs͒ barriers for strain-compensation purposes together with ͑GaIn͒͑NAs͒ active regions. In the light of metastability considerations for the ternary and quaternary alloy, one can conclude that the In contained in the quaternary material stabilizes the material and suppresses phase separation. Consequently ͑GaIn͒͑NAs͒ is more stable than its ternary counterpart Ga͑NAs͒.

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“…As there are no indications of indium diffusion after annealing, this does not seem to occur. The indium concentration decrease can be explained by an increasing number of In-N bonds, leading to a change of the 200 structure factors [8], and hence to a misassignment of the concentrations. A growing number of In-N bonds is also plausible because it minimizes the strain energy of the crystal [7] and it is discussed as a reason for the blueshift after thermal annealing [5].…”

Section: Discussionmentioning

confidence: 99%

“…To explain the blueshift of In x Ga 1-x N y As 1-y during annealing, structural properties were investigated. Some authors found evidence for an increase of preferred indiumnitrogen bonding [5,7,8], while others found evidence for long-range redistribution of nitrogen or indium [6,9]. So there might be different mechanisms contributing to the band gap increase.…”

Section: Introductionmentioning

confidence: 99%

Investigation of optical and concentration profile changes of InGaNAs/GaAs heterostructures induced by thermal annealing

Imlau

Müller

Rubel

et al. 2011

J. Phys.: Conf. Ser.

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In this contribution we compare optical and structural properties of In 0.2 Ga 0.8 N 0.024 As 0.976 quantum wells before and after annealing at 550 • C and 600 • C in an N 2 atmosphere. We measure strain and chemically sensitive contrast to determine local indium and nitrogen concentrations using a TEM 3-beam image formed by the 000, 220 and 200 beams. For quantification of the concentrations Bloch wave simulations are used, which include bonding and static atomic displacements. The samples were grown by metal-organic vapour phase epitaxy, prepared with focused ion beams (FIB), thinned with low energy ion milling and investigated in a Cs-corrected Titan 80/300 microscope using an L-shaped objective aperture. Imaging conditions with the Laue circle centre at (0 4.2 0) are used as they show a weak dependence on the lamella thickness. Absorption measurements show a blueshift of the band gap of 19 ± 7 meV (550 • C) and 36 ± 7 meV (600 • C) after annealing. The average nitrogen concentration was found to be 2 ±1 % and is unaffected by the annealing temperature. In contrast, the mean indium concentration appears to decrease from 18.5 ± 2 % before to 15 ± 1 % after annealing. Together with the blueshift, this observation is discussed in terms of a modification of electron structure factors, caused by preferred coordination of N to In atoms.

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Direct structural evidence of the change in N-III bonding in (GaIn)(NAs) before and after thermal annealing

Cited by 10 publications

References 37 publications

Simultaneous Quantification of Indium and Nitrogen Concentration in InGaNAs Using HAADF-STEM

Simultaneous Quantification of Indium and Nitrogen Concentration in InGaNAs Using HAADF-STEM

Annealing effects on the nanoscale indium and nitrogen distribution in Ga(NAs) and (GaIn)(NAs) quantum wells

Investigation of optical and concentration profile changes of InGaNAs/GaAs heterostructures induced by thermal annealing

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