Macro- and micro-strain in GaN nanowires on Si(111)

Jenichen, B.; Brandt, O.; Pfüller, Carsten; Dogan, P.; Knelangen, M.; Trampert, A.

doi:10.1088/0957-4484/22/29/295714

Cited by 66 publications

(87 citation statements)

References 20 publications

(54 reference statements)

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“…Also, the fitting procedure gives the average NW's height z equal to 400 nm, which correlates well with values obtained from cross-sectional SEM image (not shown here). The average value of microdeformation < ε ||| (z) >~1.7 × 10 − 4 is in good agreement with the values presented in [2,13] for GaN NWs grown also on Si(111). Thus, in comparison with standard WH analysis based on FWHM of 2θ/ω-scans (which gives the average value of VCL and micro-strain fluctuation), the calculation of the full XDP allows to evaluate the macroand micro-deformation depth profiles and more accurate value of the NW's height.…”

Section: Resultssupporting

confidence: 89%

“…The main sources of deterioration of NW's properties are their crystalline imperfection and residual strain. Generally, NWs are considered almost strain-free crystalline-objects without extended defects that propagate into their structure [2][3][4][5]. In comparison with thick planar epilayers, where the mechanism of lattice accommodation is preferably plastic and where the formation of misfit dislocation networks takes place, NWs are considered to be predominantly free of dislocations [6,7].…”

Section: Introductionmentioning

confidence: 99%

“…In [2], the assessment of macro-and micro-deformation in GaN NWs grown on Si(111) was performed with X-ray diffraction, where the NWs were found to be free of deformations on the macro scale but not on the micro scale. In comparison to self-assembled GaN NWs [2], an exponential relaxation of the macro-strain along the NW height was observed for top-down fabricated GaN NWs grown on silicon and sapphire substrates [3,4]. An exponential decay of the mean-squared micro-strain along the self-assembled GaN NW was considered to describe the X-ray diffraction peaks in [8].…”

Section: Introductionmentioning

confidence: 99%

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High-resolution X-ray diffraction analysis of strain distribution in GaN nanowires on Si(111) substrate

Stanchu¹,

Kladko²,

Kuchuk³

et al. 2016

Nano Online

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In this work, the influence of micro-and macro-deformation profiles in GaN nanowires (NWs) on the angular intensity distribution of X-ray diffraction are studied theoretically. The calculations are performed by using kinematical theory of X-ray diffraction and assuming the deformation decays exponentially from the NW/substrate interface. Theoretical modeling of X-ray scattering from NWs with different deformation profiles are carried out. We show that the shape of the (002) 2θ/ω X-ray diffraction profile (XDP) is defined by initial deformation at the NW's bottom and its relaxation depth given by the decay depth of the exponential deformation profile. Also, we demonstrate that macro-deformation leads to XDP shift, whereas micro-deformations are the cause of XDP's asymmetry and its symmetrical broadening. A good correlation between calculated and experimental XDP from self-assembled GaN NWs on Si(111) substrate was achieved by taking into account all parameters of micro-and macro-deformation profiles.

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Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

High-resolution X-ray diffraction analysis of strain distribution in GaN nanowires on Si(111) substrate

Stanchu¹,

Kladko²,

Kuchuk³

et al. 2016

Nano Online

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“…22 At these coalesced nanorod regions the mutual misorientation results in extended defects such as basal plane stacking faults and dislocations when the strain cannot be accommodated elastically. [23][24][25] The increased strain caused by the coalescence has a significant impact on the optical properties of the nanorod LEDs: as reported by several groups the PL peaks broaden greatly with increasing fill factor. 19,[26][27][28] Furthermore, additional peaks associated with basal stacking faults 25,29 and threading dislocations 30 only begin to appear above a certain fill factor.…”

Section: Introductionmentioning

confidence: 84%

Site controlled red-yellow-green light emitting InGaN quantum discs on nano-tipped GaN rods

Conroy¹,

Kusch

et al. 2016

Nanoscale

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We report a method of growing site controlled InGaN multiple quantum discs (QDs) at uniform wafer scale on coalescence free ultra-high density (>80%) nanorod templates by metal organic chemical vapour deposition (MOCVD). The dislocation and coalescence free nature of the GaN space filling nanorod arrays eliminates the well-known emission problems seen in InGaN based visible light sources that these types of crystallographic defects cause. Correlative scanning transmission electron microscopy (STEM), energy-dispersive X-ray (EDX) mapping and cathodoluminescence (CL) hyperspectral imaging illustrates the controlled site selection of the red, yellow and green (RYG) emission at these nano tips. This article reveals that the nanorod tips' broad emission in the RYG visible range is in fact achieved by manipulating the InGaN QD's confinement dimensions, rather than significantly increasing the In%. This article details the easily controlled method of manipulating the QDs dimensions producing high crystal quality InGaN without complicated growth conditions needed for strain relaxation and alloy compositional changes seen for bulk planar GaN templates

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“…The FWHM in angular direction here corresponds to the range of twist of the NWs, as in-plane reflections are used. 35 The range of tilt of GaAs NWs was measured to be near (0.28±0.1) • using symmetrical out-of-plane measurements. maxima due to polycrystalline material whereas scan (b) exhibits additional maxima caused by the wurtzite regions in the GaAs cores.…”

Section: Resultsmentioning

confidence: 94%

Diffraction at GaAs/Fe3Si core/shell nanowires: The formation of nanofacets

et al. 2016

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GaAs/Fe 3 Si core/shell nanowire structures were fabricated by molecular-beam epitaxy on oxidized Si(111) substrates and investigated by synchrotron x-ray diffraction. The surfaces of the Fe 3 Si shells exhibit nanofacets. These facets consist of well pronounced Fe 3 Si{111} planes. Density functional theory reveals that the Si-terminated Fe 3 Si{111} surface has the lowest energy in agreement with the experimental findings. We can analyze the x-ray diffuse scattering and diffraction of the ensemble of nanowires avoiding the signal of the substrate and poly-crystalline films located between the wires. Fe 3 Si nanofacets cause streaks in the x-ray reciprocal space map rotated by an azimuthal angle of 30 • compared with those of bare GaAs nanowires. In the corresponding TEM micrograph the facets are revealed only if the incident electron beam is oriented along [110] in accordance with the x-ray results. Additional maxima in the x-ray scans indicate the onset of chemical reactions between Fe 3 Si shells and GaAs cores occurring at increased growth temperatures.

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Macro- and micro-strain in GaN nanowires on Si(111)

Cited by 66 publications

References 20 publications

High-resolution X-ray diffraction analysis of strain distribution in GaN nanowires on Si(111) substrate

High-resolution X-ray diffraction analysis of strain distribution in GaN nanowires on Si(111) substrate

Site controlled red-yellow-green light emitting InGaN quantum discs on nano-tipped GaN rods

Diffraction at GaAs/Fe3Si core/shell nanowires: The formation of nanofacets

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