Quadrupolar NMR of Semiconductors

Yesinowski, James P.

doi:10.1002/9780470034590.emrstm1220

Cited by 2 publications

(3 citation statements)

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“…As has been reviewed by Yesinowski 1,2 there is interest in nanoscaled semiconductors, and with improvements in sensitivity and resolution, the area of semiconductor NMR is being rejuvenated. Spontaneous atomic ordering of semiconductor alloys is of great practical and fundamental interest and the ordering of III-V alloys has been extensively studied.…”

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A multi-nuclear magnetic resonance and density functional theory investigation of epitaxially grown InGaP₂

Knijn

Bentum

Fang

et al. 2016

Phys. Chem. Chem. Phys.

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In this paper the short and long range order in In0.483Ga0.517P thin films is investigated by solid-state Nuclear Magnetic Resonance (NMR) spectroscopy. To this end two samples were grown on a GaAs substrate by metal-organic vapor phase epitaxy at two different growth-pressures. From band gap energy measurements, CuPt long range order parameters of SCuPt = 0.22 and 0.39 were deduced, respectively. In the (31)P spectrum five resonances are observed corresponding to the five possible P(GanIn4-n), n = 0-4, coordinations whose relative intensities correspond to the order in the material, but the intensity variations for order parameters between 0 and 0.5 are minimal. (69)Ga, (71)Ga and (115)In (MQ)MAS spectra were acquired to analyze the quadrupolar and chemical shift distributions related to the (dis)order in these materials in more detail. All these spectra clearly reflect the disorder in the sample and do not show the presence of highly ordered domains. The difference in the order parameter in the sample is not clearly reflected in the spectra. (31)P chemical shifts were calculated using Density Functional Theory. The experimentally observed shifts are well reproduced with a simple random model of the disorder, thus confirming the assignment of the resonances. The (31)P chemical shifts are very sensitive to changes in the lattice parameter and chemical surroundings. These effects nearly compensate and explain why the (31)P chemical shifts in pure InP and GaP are nearly identical whereas a large difference would be expected based on the observed shift difference for the P[In4] and P[Ga4] coordinations in In0.483Ga0.517P.

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A multi-nuclear magnetic resonance and density functional theory investigation of epitaxially grown InGaP₂

Knijn

Bentum

Fang

et al. 2016

Phys. Chem. Chem. Phys.

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“…The magnetic relaxation mechanisms involve a single relaxation rate 3 W , 4 W , and drive single‐quantum (SQ) transitions between energy levels. In contrast, the quadrupolar relaxation mechanism drives SQ and double quantum (DQ) transitions between the energy levels with the corresponding rates W 1 and W 2 .…”

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“…The recovery of an enhanced population difference at the CT during the populations transfer experiment [Fig. (d)] will depend also on its initial condition . The relaxation paths are shown as arrows in Fig.…”

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confidence: 99%

AFNMR/NQR signal enhancement via population transfer

Lehmann-Horn

Miljak

2014

Concepts Magnetic Resonance

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Antiferromagnetic nuclear magnetic resonance (AFNMR) and nuclear quadrupole resonance (NQR) are useful techniques to characterize materials in bulk volumes without applying external static magnetic fields. For industrial materials characterization applications, it is crucial to maximize signal‐to‐noise ratio in the available time. We simulate the AFNMR and NQR signal enhancement via population transfer in single crystals and powders and predict the enhancement factors for half‐integer quadrupolar nuclei spin systems. Differences to conventional high‐field NMR population transfer experiments are emphasized. We restrict our discussion to electric field gradients with axial symmetry η = 0. Triple resonance tuned crossed coil experiments on CuFeS2 and In2O3 powders support the numerical results. © 2015 Wiley Periodicals, Inc. Concepts Magn Reson Part A 43A: 147–156, 2015.

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Quadrupolar NMR of Semiconductors

Cited by 2 publications

References 86 publications

A multi-nuclear magnetic resonance and density functional theory investigation of epitaxially grown InGaP₂

A multi-nuclear magnetic resonance and density functional theory investigation of epitaxially grown InGaP₂

AFNMR/NQR signal enhancement via population transfer

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Quadrupolar NMR of Semiconductors

Cited by 2 publications

References 86 publications

A multi-nuclear magnetic resonance and density functional theory investigation of epitaxially grown InGaP2

A multi-nuclear magnetic resonance and density functional theory investigation of epitaxially grown InGaP2

AFNMR/NQR signal enhancement via population transfer

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A multi-nuclear magnetic resonance and density functional theory investigation of epitaxially grown InGaP₂

A multi-nuclear magnetic resonance and density functional theory investigation of epitaxially grown InGaP₂