Quantitative analysis of variant III CuAu-I-type ordering of AlxGa1−xAs on (110), (111)A and (001) GaAs substrates using X-ray diffraction

Niftrik, A.T.J. van; Bauhuis, G.J.; Schermer, J.J.; Kim, H.J.; Voncken, M. M. A. J.; Mulder, P.; Larsen, P.K.

doi:10.1016/j.jcrysgro.2005.10.133

Cited by 4 publications

(7 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…X-ray measurements from Kuan 6 et al reported a low long-range order parameter S o 0.5 for Al 0.75 Ga 0.25 As grown by MOCVD, depending on growth conditions. More recent X-ray measurements by van Niftrik et al 7 indicated a lower long-range ordering of S r 0.05 for Al 0.5 Ga 0.5 As and S r 0.06 for Al 0.25 Ga 0.75 As. Despite the prediction of almost no long-range ordering with X-ray, studies of the local interface for dilute AlGaAs with crosssectional STM (XSTM) indicate the appearance of short strings.…”

Section: Introductionmentioning

confidence: 89%

“…To deal with this situation an extension of the Czjzek approach is needed, considering the case of an EFG contribution of a well-defined local coordination of a given atomic species and adding to that the effect of disorder of more remote atomic shells and possible other random contributions to the total EFG. Due to the good lattice matching of the Table 1 The ratio of the average hV zz i to the s in a Czjzek distribution as a function of the power factor d obtained by integrating eqn (7) AlGaAs lattice, we neglect any stress in the lattice and propose to use additivity for the local and remote contributions to these EFGs. This is implemented numerically by adding the (fixed) contribution of the first coordination shell to the Czjzek distribution resulting from (random) occupancy of Al and Ga lattice sites in the further coordination shells.…”

Section: Introductionmentioning

confidence: 99%

“…with A ij (a, b, g) as defined in ref. 26 and A as in eqn (7). For Z(0) = 0 this equation can be written into a modified Bessel function form (see eqn 61 in ref.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A solid-state NMR and DFT study of compositional modulations in AlxGa1−xAs

Knijn

Bentum

Eck

et al. 2010

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

We have conducted (75)As and (69)Ga Nuclear Magnetic Resonance (NMR) experiments to investigate order/disorder in Al(x)Ga(1-x)As lift-off films with x∼ 0.297 and 0.489. We were able to identify all possible As(Al(n)Ga(4-n)) sites with n = 0-4 coordinations in (75)As NMR spectra using spin-echo experiments at 18.8 Tesla. This was achieved by employing high rf field strengths using a small solenoid coil and an NMR probe specifically designed for this purpose. Spectral deconvolution, using an evolutionary algorithm, complies with the absence of long-range order if a CuAu based order parameter is imposed. An unconstrained fit shows a deviation of the statistics imposed by this type of ordering. The occupational disorder in the Ga and Al positions is reflected in a distribution of the Electric Field Gradients (EFGs) experienced at the different arsenic sites. We established that this can be modelled by summing the effects of the first coordination sphere and a Czjzek type distribution resulting from the compositional variation in the Al/Ga sub-lattice in the higher coordination spheres. (69)Ga 3QMAS and nutation data exclude the presence of highly symmetric sites and also show a distribution in EFG. The experimentally obtained quadrupolar interactions are in good agreement with calculations based on Density Functional Theory (DFT). Using additivity of EFG tensors arising from distant charge perturbations, we could use DFT to model the EFG distributions of the n = 0-4 sites, reproducing the Czjzek and extended Czjzek distributions that were found experimentally. On the basis of these calculations we conclude that the (75)As quadrupolar interaction is sensitive to compositional modulations up to the 7th coordination shell in these systems.

show abstract

Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A solid-state NMR and DFT study of compositional modulations in AlxGa1−xAs

Knijn

Bentum

Eck

et al. 2010

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…AlGaAs is a well-known semiconductor with interesting electronic and photonic properties. Using X-ray measurements and other analytic techniques, a random distribution of the Al and Ga cations within the fixed anion fcc lattice structure was found. Considering the limited number of reports , on long-range order in AlGaAs thin films as studied by diffraction techniques, whereas specific ordered structures are seen in a number of microscopic observations (such as SEM and TEM), it is interesting to study these materials with a complementary method such as NMR.…”

Section: Introductionmentioning

confidence: 99%

Stripline ⁷⁵As NMR Study of Epitaxial III–V Semiconductor Al_0.5Ga_0.5As

et al. 2014

View full text Add to dashboard Cite

We have carried out 75As NMR experiments on a single 5 μm thick epitaxial layer of metal organic chemical vapor deposition (MOCVD) Al x Ga1–x As, with x = 0.522, using a novel stripline based NMR setup. Different arsenic surroundings in the lattice give rise to five As[Al n Ga4–n ] sites with (n = 0–4). By mounting a thin film of Al0.522Ga0.478As in a home-built NMR probe with rotation stage and stripline detector, we could successfully distinguish different arsenic nearest neighbors coordinations. Furthermore, we were able to observe various 75As quadrupolar tensor orientations for each As[Al n Ga4–n ] coordination, which gives us a unique insight into the structure of this material. The individual resonances for each of these coordinations appear to be very broad, as a result of the variation in the local symmetry due to the distribution of aluminum and gallium over the lattice. In particular, the NMR resonance of one orientation of the As[Al2Ga2] site is strongly broadened. The line widths prove to be larger than predicted on the basis of the (distribution in) quadrupolar interaction parameters obtained in a previous study of powdered Al x Ga1–x As films (P. J. Knijn et al. Phys. Chem. Chem. Phys. 2010, 12, 11517–11535). In Density Functional Theory (DFT) based calculations, these wider distributions in quadrupolar interaction parameters can be explained by local variations in the first coordination sphere of arsenic, which become apparent when the internal structure is relaxed before quantum mechanical calculations of the Electric Field Gradient Tensors (EFGs). A detailed simulation of the NMR line intensities, taking the actual NMR excitation parameters into account, prove the absence of any kind of local or long-range order in the occupation of the Al/Ga sites in the lattice.

show abstract

“…However, the definition of chemical order parameter introduced in these papers is correct only for binary alloys. In case of ternary alloys we have to take into account the problem of site occupation by dopant atoms [31,32].…”

Section: Introductionmentioning

confidence: 99%

Chemical order and crystallographic texture of FePd:Cu thin alloy films

Perzanowski

Zabila

Krupiński

et al. 2012

Journal of Applied Physics

View full text Add to dashboard Cite

FePd thin films have been recently considered as promising material for high-density magnetic storage devices. However, it is necessary to find a proper method of fabrication for the (001)-textured and chemically well-ordered alloy. In this paper, we present the detailed investigations of lattice parameters, chemical order degree, grain sizes and crystallographic texture, carried out on FePd alloys with 10 at.% of Cu addition. The initial [Cu(0.2 nm)/Fe(0.9 nm)/Pd(1.1 nm)]x5 multilayers were thermally evaporated in an ultra-high vacuum on MgO(100), Si(100), Si(111) and Si(100) covered by 100 nm thick layer of amorphous SiO2. In order to obtain homogeneous FePd:Cu alloy, the multilayers were annealed in two different ways. First, the samples were rapidly annealed in nitrogen atmosphere at 600oC for 90 seconds. Next, the long annealing in a high vacuum for 1 hour at 700oC was done. This paper focuses on quantitative investigations of the chemical order degree and crystallographic texture of ternary FePd:Cu alloys deposited on four different substrates. In order to obtain both quantities we have taken a novel approach to consider the problem of dopant atoms located in the FePd structure. The studies of the structure were done using X-Ray Diffraction (XRD) performed with synchrotron radiation and pole figures measurements. We have found that the addition of Cu changes the FePd lattice parameters and lattice distortion. We have also shown, that using different substrates it is possible to obtain a FePd:Cu alloy with different chemical order and texture. Moreover, it was observed that texture category is substrate dependent

show abstract

Quantitative analysis of variant III CuAu-I-type ordering of AlxGa1−xAs on (110), (111)A and (001) GaAs substrates using X-ray diffraction

Cited by 4 publications

References 38 publications

A solid-state NMR and DFT study of compositional modulations in AlxGa1−xAs

A solid-state NMR and DFT study of compositional modulations in AlxGa1−xAs

Stripline ⁷⁵As NMR Study of Epitaxial III–V Semiconductor Al_0.5Ga_0.5As

Chemical order and crystallographic texture of FePd:Cu thin alloy films

Contact Info

Product

Resources

About

Quantitative analysis of variant III CuAu-I-type ordering of AlxGa1−xAs on (110), (111)A and (001) GaAs substrates using X-ray diffraction

Cited by 4 publications

References 38 publications

A solid-state NMR and DFT study of compositional modulations in AlxGa1−xAs

A solid-state NMR and DFT study of compositional modulations in AlxGa1−xAs

Stripline 75As NMR Study of Epitaxial III–V Semiconductor Al0.5Ga0.5As

Chemical order and crystallographic texture of FePd:Cu thin alloy films

Contact Info

Product

Resources

About

Stripline ⁷⁵As NMR Study of Epitaxial III–V Semiconductor Al_0.5Ga_0.5As