Quantitative strain analysis of surfaces and interfaces using extremely asymmetric x-ray diffraction

Akimoto, Koichi; Emoto, Takashi

doi:10.1088/0953-8984/22/47/473001

Cited by 4 publications

(4 citation statements)

References 82 publications

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“…Considering that the size of our NWs is similar across the composition range and too large to significantly broaden the XRD peaks, our data are indicative of minor lattice constant fluctuations and a disordered crystal lattice in the In x Ga 1– x P NWs. Asymmetries in the diffraction peaks may be due to the presence of dislocations, lattice strain, or fluctuations in composition within individual nanowires or within the batch. , The lattice constant of the NWs determined from the XRD measurements shifts linearly with NW composition in accordance with Vegard’s law (Figure B), which predicts such a linear relation in an ensemble measurement of a random mixture where small structural fluctuations are averaged out . The lack of significant deviations from Vegard’s law or multiple (111) peaks in the XRD spectra indicates the absence of significant phase segregation in the In x Ga 1– x P NWs.…”

Section: Resultsmentioning

confidence: 84%

Solution Phase Synthesis of Indium Gallium Phosphide Alloy Nanowires

Kornienko¹,

Whitmore²,

Yu³

et al. 2015

ACS Nano

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The tunable physical and electronic structure of III-V semiconductor alloys renders them uniquely useful for a variety of applications, including biological imaging, transistors, and solar energy conversion. However, their fabrication typically requires complex gas phase instrumentation or growth from high-temperature melts, which consequently limits their prospects for widespread implementation. Furthermore, the need for lattice matched growth substrates in many cases confines the composition of the materials to a narrow range that can be epitaxially grown. In this work, we present a solution phase synthesis for indium gallium phosphide (In(x)Ga(1-x)P) alloy nanowires, whose indium/gallium ratio, and consequently, physical and electronic structure, can be tuned across the entire x = 0 to x = 1 composition range. We demonstrate the evolution of structural and optical properties of the nanowires, notably the direct to indirect band gap transition, as the composition is varied from InP to GaP. Our scalable, low-temperature synthesis affords compositional, structural, and electronic tunability and can provide a route for realization of broader In(x)Ga(1-x)P applications.

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Section: Resultsmentioning

confidence: 84%

Solution Phase Synthesis of Indium Gallium Phosphide Alloy Nanowires

Kornienko¹,

Whitmore²,

Yu³

et al. 2015

ACS Nano

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“…However, until now, mechanical stress property has not been investigated at the interface of organic optoelectronic devices because no valid method is available for detection. It is well known that interface mechanical stress plays a vital role in many failures and reliability problems (11)(12)(13)(14) of conventional inorganic optoelectronic devices and emerging perovskite solar cell and two-dimensional materials (15)(16)(17)(18). The unrevealed interface stress in organic interface directly leads to the unknown relationship between stress and device stability.…”

Section: Introductionmentioning

confidence: 99%

Revealing molecular conformation–induced stress at embedded interfaces of organic optoelectronic devices by sum frequency generation spectroscopy

et al. 2021

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Interface stresses are pervasive and critical in conventional optoelectronic devices and generally lead to many failures and reliability problems. However, detection of the interface stress embedded in organic optoelectronic devices is a long-standing problem, which causes the unknown relationship between interface stress and organic device stability (one key and unsettled issue for practical applications). In this study, a kind of previously unknown molecular conformation–induced stress is revealed at the organic embedded interface through sum frequency generation (SFG) spectroscopy technique. This stress can be greater than 10 kcal/mol per nm2 and is sufficient to induce molecular disorder in the organic semiconductor layer (with energy below 8 kcal/mol per nm2), finally causing instability of the organic transistor. This study not only reveals interface stress in organic devices but also correlates instability of organic devices with the interface stress for the first time, offering an effective solution for improving device stability.

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“…In this equation, a characteristic matrix corresponding to the atomic layer is defined. In other words, if we desire to calculate the reflectivity of x-rays for a crystal including an irregular structure like a reconstructed semiconductor surface or strain, we can prepare the characteristic matrix corresponding to the irregular atomic layers, and then multiply this with the matrix for bulk [14].…”

Section: Calculationmentioning

confidence: 99%

Behavior of Peak Intensity of Rocking Curve for Asymmetric Bragg Reflection Uniquely Determined by Strain Distribution

Emoto

2013

e-J. Surf. Sci. Nanotechnol.

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Extremely asymmetric x-ray diffraction is a powerful technique for observing minute strains near crystal surfaces. This work focused on the peak intensity of the rocking curve and studied the change in peak intensity with respect to the wavelength of x-rays using dynamical diffraction calculations. From the calculations assuming uniaxial strain along the depth direction of the crystal, it was found that the peak intensity becomes more sensitive to strain as the wavelength decreases below a critical value (critical wavelength λc) at which the total reflection of incident x-rays is enhanced. Comparing the profile of peak intensity vs. wavelength for a strained crystal with that for an unstrained crystal, it is clear that the introduction of compressive or tensile strain causes either enhancement or reduction of the intensity. The difference spectra generated by subtraction of the profile of peak intensity vs. wavelength for an unstrained crystal from that for a strained crystal shows a systematic change with respect to the strain parameters, the maximum strain value ε0 and the thickness of the strained layer H. It is expected that we can evaluate the strain more quickly and easily by fitting the difference spectra than by using the rocking curves when the rocking curves are featureless.

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Quantitative strain analysis of surfaces and interfaces using extremely asymmetric x-ray diffraction

Cited by 4 publications

References 82 publications

Solution Phase Synthesis of Indium Gallium Phosphide Alloy Nanowires

Solution Phase Synthesis of Indium Gallium Phosphide Alloy Nanowires

Revealing molecular conformation–induced stress at embedded interfaces of organic optoelectronic devices by sum frequency generation spectroscopy

Behavior of Peak Intensity of Rocking Curve for Asymmetric Bragg Reflection Uniquely Determined by Strain Distribution

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