Composition fluctuations in dilute nitride (Ga,In)(N,As)/GaAs heterostructures measured by low-loss electron energy-loss spectroscopy

Kong, Xiang-Shan; Trampert, A.

doi:10.1016/j.micron.2005.11.008

Cited by 8 publications

(5 citation statements)

References 29 publications

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“…For this purpose, we studied two equivalent QWs with the same thickness and composition, but grown with and without the application of the deflecting magnetic field, by TEM as the epilayers studied above by AFM. 21,[25][26][27] These fluctuations in the composition are spaced between 20 and 100 nm, as observed in Fig. 21,25 As observed in this figure, very small thickness fluctuations were found, indicating a pure 2D growth mode during the epitaxy of the layers.…”

Section: B Transmission Electron Microscope Investigationssupporting

confidence: 66%

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Role of ionized nitrogen species in the optical and structural properties of GaInNAs/GaAs quantum wells grown by plasma-assisted molecular beam epitaxy

Miguel‐Sánchez

Guzmán

Jahn

et al. 2007

Journal of Applied Physics

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Internal quantum efficiency of III-nitride quantum dot superlattices grown by plasma-assisted molecular-beam epitaxy J. Appl. Phys. 109, 103501 (2011); 10.1063/1.3590151GaInNAs/GaAs quantum wells grown by molecular-beam epitaxy emitting above 1.5 μm Appl.We report on the impact of the nitrogen ion density on the structural and optical properties of GaInNAs quantum wells ͑QWs͒ grown by molecular beam epitaxy. The optical emission is strongly increased when the nitrogen ion density is reduced, as we found from photoluminescence experiments. Cathodoluminescence mappings of QWs grown under different ion densities are compared, showing a stronger modulation depth, and thus a higher structural disorder when a higher ion density was present during the growth. Atomic force microscopy measurements of equivalent epilayers showed that ions cause an important structural disorder of the layers. A nearly double root-mean-square roughness is observed when the density of ions is not reduced by external magnetic fields. Additionally, results of transmission electron microscopy measurements of buried GaInNAs QWs are presented, showing that lateral compositional fluctuations of In and N are suppressed when the QWs are protected from the ions. Finally, we find that QWs exposed to higher ion densities during the growth show deeper carrier localization levels and higher delocalization temperatures. These results provide clear evidence that the density of nitrogen ions present in the chamber during the epitaxial growth of GaInNAs QWs directly limits both the structural and optical properties.

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Section: B Transmission Electron Microscope Investigationssupporting

confidence: 66%

“…This is consistent with the earlier mentioned RHEED observations. 26,27 In the case under study, we clearly observe that for the GaInNAs/GaAs QWs grown under the same conditions, these fluctuations are strongly reduced, if the ion density is decreased. Fig.…”

Section: B Transmission Electron Microscope Investigationsmentioning

confidence: 71%

Role of ionized nitrogen species in the optical and structural properties of GaInNAs/GaAs quantum wells grown by plasma-assisted molecular beam epitaxy

Miguel‐Sánchez

Guzmán

Jahn

et al. 2007

Journal of Applied Physics

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“…In addition, the XRD signals are obtained at a macroscopic scale and thus only offer an average result of NW arrays, which are highly dispersed in NW diameters, lengths and likely compositions. Low-loss electron energy-loss spectroscopy (EELS) in TEM has been demonstrated to be a powerful technique for probing the chemical composition on the nanometer scale [9][10][11][12][13]. Compared to core-loss EELS, the low-loss EELS method has a slightly decreased spatial resolution due to the relatively large delocalization of low-loss inelastic scattering [14].…”

Section: Introductionmentioning

confidence: 99%

Plasmon excitation in electron energy-loss spectroscopy for determination of indium concentration in (In,Ga)N/GaN nanowires

et al. 2012

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We demonstrate the potential of low-loss electron energy-loss spectroscopy in transmission electron microscopy as a quick and straightforward method to determine the local indium compositions in (In,Ga)N/GaN nanowires. The (In,Ga)N/GaN nanowire heterostructures are grown by plasma assisted molecular beam epitaxy on Si(111) substrates in a self-assembled way, and on patterned GaN templates in an ordered way. A wide range of indium contents is realized by varying the substrate temperatures. The plasmon peak in low-loss electron energy-loss spectroscopy exhibits a linear relation with respect to indium concentration in (In,Ga)N nanowires, allowing for a direct compositional analysis. The high spatial resolution of this method in combination with structural information from transmission electron microscopy will contribute to a basic understanding of the lattice pulling effect during (In,Ga)N/GaN nanowire growth.

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“…The introduction of a fourth element in GaAsN alloys with a larger radius than GaAs elements, such as In or Sb, facilitates the growth of high-quality layers, as it compensates for the tensile effect of N [17]. However, in the case of GaInAsN, the need to incorporate more than 2% N and 25% In to reach the desired wavelength range causes large fluctuations in the composition and roughness of the interface, which decreases structural quality [18,19,20]. In the case of GaAsSbN, the high improvement of the photoluminescence (PL) by the incorporation of Sb has been generally attributed to a more homogeneous distribution of N, and to a reduction in the formation of N complexes [21,22,23].…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, it is widely accepted that the rapid thermal annealing (RTA) process improves the homogeneity of N within dilute nitride layers, and this is based on the increase of the PL intensity, decreasing its full width at half maximum (FWHM) after RTA [25,26,27]. However, there are no direct measurements of the improvement in the disorder after annealing treatment in dilute nitrides, probably due to the difficulty in spatially resolving the distribution of N [20,28]. In addition, the possibility of a synergistic effect in the case of GaAsSbN layers, by combining the presence of Sb and post-growth annealing, should not be ruled out.…”

Section: Introductionmentioning

confidence: 99%

Control of Nitrogen Inhomogeneities in Type-I and Type-II GaAsSbN Superlattices for Solar Cell Devices

et al. 2019

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Superlattice structures (SLs) with type-II (GaAsSb/GaAsN) and -I (GaAsSbN/GaAs) band alignments have received a great deal of attention for multijunction solar cell (MJSC) applications, as they present a strongly intensified luminescence and a significant external quantum efficiency (EQE), with respect to the GaAsSbN bulk layers. Despite the difficulties in characterizing the distribution of N in dilute III-V nitride alloys, in this work we have obtained N-compositional mappings before and after rapid thermal annealing (RTA) in both types of structures, by using a recent methodology based on the treatment of different scanning transmission electron microscopy (STEM) imaging configurations. Texture analysis by gray level co-occurrence matrixes (GLCM) and the measurement of the degree of clustering are used to compare and evaluate the compositional inhomogeneities of N. Comparison with the Sb maps shows that there is no spatial correlation between the N and Sb distributions. Our results reveal that a better homogeneity of N is obtained in type-I SLs, but at the expense of a higher tendency of Sb agglomeration, and the opposite occurs in type-II SLs. The RTA treatments improve the uniformity of N and Sb in both designs, with the annealed sample of type-II SLs being the most balanced structure for MJSCs.

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Composition fluctuations in dilute nitride (Ga,In)(N,As)/GaAs heterostructures measured by low-loss electron energy-loss spectroscopy

Cited by 8 publications

References 29 publications

Role of ionized nitrogen species in the optical and structural properties of GaInNAs/GaAs quantum wells grown by plasma-assisted molecular beam epitaxy

Role of ionized nitrogen species in the optical and structural properties of GaInNAs/GaAs quantum wells grown by plasma-assisted molecular beam epitaxy

Plasmon excitation in electron energy-loss spectroscopy for determination of indium concentration in (In,Ga)N/GaN nanowires

Control of Nitrogen Inhomogeneities in Type-I and Type-II GaAsSbN Superlattices for Solar Cell Devices

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