X-ray Bragg Ptychography on a Single InGaN/GaN Core–Shell Nanowire

Dzhigaev, Dmitry; Stankevič, Tomaš; Bi, Zhaoxia; Lazarev, Sergey; Rose, M. Franklin; Shabalin, Anatoly; Reinhardt, Juliane; Mikkelsen, Anders; Samuelson, Lars; Falkenberg, Gerald; Feidenhans’l, R.; Vartanyants, Ivan A.

doi:10.1021/acsnano.6b08122

Cited by 44 publications

(20 citation statements)

References 42 publications

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“…while for TEM the sequential measurement of numerous NWs is required. At the same time, recent achievements in preparing x-ray beams with nanometer diameter at synchrotron radiation sources [30] allow nowadays also the study of individual NWs [31][32][33][34]. The key benefit of the approach based on x rays is that NWs can be investigated in their as-grown configuration on the substrate, while characterization by TEM requires a destructive sample preparation.…”

Section: Introductionmentioning

confidence: 99%

Determination of indium content of GaAs/(In,Ga)As/(GaAs) core-shell(-shell) nanowires by x-ray diffraction and nano x-ray fluorescence

Hassan

Lewis

Küpers

et al. 2018

Phys. Rev. Materials

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We present two complementary approaches to investigate the In content in GaAs/(In,Ga)As/(GaAs) core-shell-(shell) nanowire (NW) heterostructures using synchrotron radiation. The key advantage of our methodology is that NWs are characterized in their as-grown configuration, i.e., perpendicularly standing on a substrate. First, we determine the mean In content of the (In,Ga)As shell by high-resolution x-ray diffraction (XRD) from NW ensembles. In particular, we disentangle the influence of In content and shell thickness on XRD by measuring and analyzing two reflections with diffraction vector parallel and perpendicular to the growth axis, respectively. Second, we study the In distribution within individual NWs by nano x-ray fluorescence. Both the NW (111) basal plane, that is parallel to the surface of the substrate, and the {10-1} sidewall plane were scanned with an incident nanobeam of 50 nm width. We investigate three samples with different nominal In content of the (In,Ga)As shell. In all samples, the average In content of the shell determined by XRD is in good agreement with the nominal value. For a nominal In content of 15%, the In distribution is fairly uniform between all six sidewall facets. In contrast, in NWs with nominally 25% In content, different sidewall facets of the same NW exhibit different In contents. This effect is attributed to shadowing during growth by molecular beam epitaxy. At the same time, along the NW axis the In distribution is still fairly homogeneous. In NWs with 60% nominal In content and no outer GaAs shell, the In content varies significantly both between different sidewall facets and along the NW axis. This fluctuation is explained by the formation of (In,Ga)As mounds that grow simultaneously with a thinner (In,Ga)As shell. The methodology presented here may be applied also to other core-shell NWs with a ternary shell and paves the way to correlating NW structure with functional properties that depend on the as-grown configuration of the NWs.

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Section: Introductionmentioning

confidence: 99%

Determination of indium content of GaAs/(In,Ga)As/(GaAs) core-shell(-shell) nanowires by x-ray diffraction and nano x-ray fluorescence

Hassan

Lewis

Küpers

et al. 2018

Phys. Rev. Materials

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“…21 . The main functions of this beamline include XEOL, TR-XEOL, XRF, XAS, CL, XRD and Bragg ptychography 22 with high spatial and temporal resolution so that in a single probe one can simultaneously obtain the optical, compositional and structural information. The SEM was equipped in a high vacuum chamber (1 × 10 −6 torr) with a load-lock system to quickly transfer the samples between the main chamber and the preparation chamber.…”

Section: Methodsmentioning

confidence: 99%

Investigation of Cavity Enhanced XEOL of a Single ZnO Microrod by Using Multifunctional Hard X-ray Nanoprobe

Lin

et al. 2019

Sci Rep

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The multifunctional hard X-ray nanoprobe at Taiwan Photon Source (TPS) exhibits the excellent ability to simultaneously characterize the X-ray absorption, X-ray excited optical luminescence (XEOL) as well as the dynamics of XEOL of materials. Combining the scanning electron microscope (SEM) into the TPS 23A end-station, we can easily and quickly measure the optical properties to map out the morphology of a ZnO microrod. A special phenomenon has been observed that the oscillations in the XEOL associated with the confinement of the optical photons in the single ZnO microrod shows dramatical increase while the X-ray excitation energy is set across the Zn K-edge. Besides having the nano-scale spatial resolution, the synchrotron source also gives a good temporal domain measurement to investigate the luminescence dynamic process. The decay lifetimes of different emission wavelengths and can be simultaneously obtained from the streak image. Besides, SEM can provide the cathodoluminescence (CL) to be a complementary method to analyze the emission properties of materials, we anticipate that the X-ray nanoprobe will open new avenues with great characterization ability for developing nano/microsized optoelectronic devices.

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“…Moreover, although there is consensus in the literature about the phase of the reconstructed object [represented with a term exp(iG Áu), where G is the probed reciprocal lattice vector and u the displacement field in the crystal], one finds different expressions for its amplitude: some authors consider that it is the electron density, others that it is the structure factor. The clarification of this point is particularly important when quantitative studies are undertaken on crystals with heterogeneous compositions, as done, for example, by Pateras et al (2015) and Dzhigaev et al (2017).…”

Section: Introductionmentioning

confidence: 99%

On the use of the scattering amplitude in coherent X-ray Bragg diffraction imaging

Godard

2021

J Appl Crystallogr

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Lens-less imaging of crystals with coherent X-ray diffraction offers some unique possibilities for strain-field characterization. It relies on numerically retrieving the phase of the scattering amplitude from a crystal illuminated with coherent X-rays. In practice, the algorithms encode this amplitude as a discrete Fourier transform of an effective or Bragg electron density. This short article suggests a detailed route from the classical expression of the (continuous) scattering amplitude to this discrete function. The case of a heterogeneous incident field is specifically detailed. Six assumptions are listed and quantitatively discussed when no such analysis was found in the literature. Details are provided for two of them: the fact that the structure factor varies in the vicinity of the probed reciprocal lattice vector, and the polarization factor, which is heterogeneous along the measured diffraction patterns. With progress in X-ray sources, data acquisition and analysis, it is believed that some approximations will prove inappropriate in the near future.

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X-ray Bragg Ptychography on a Single InGaN/GaN Core–Shell Nanowire

Cited by 44 publications

References 42 publications

Determination of indium content of GaAs/(In,Ga)As/(GaAs) core-shell(-shell) nanowires by x-ray diffraction and nano x-ray fluorescence

Determination of indium content of GaAs/(In,Ga)As/(GaAs) core-shell(-shell) nanowires by x-ray diffraction and nano x-ray fluorescence

Investigation of Cavity Enhanced XEOL of a Single ZnO Microrod by Using Multifunctional Hard X-ray Nanoprobe

On the use of the scattering amplitude in coherent X-ray Bragg diffraction imaging

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