Journal articles: 'Wurtzite crystal'

1

Hostettler, M., and H. D. Flack. "Anti-wurtzite reoriented." Acta Crystallographica Section B Structural Science 59, no. 4 (July 25, 2003): 537–38. http://dx.doi.org/10.1107/s0108768103009467.

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Anti-wurtzite and wurtzite are shown to be the same crystal structure despite the claims of a recent paper describing the crystal structure of the mineral rambergite, Mn1−x Fe x S, x ≃ 0.05. The anti-wurtzite/wurtzite confusion is used as an illustration to help clarify the correct general approach to take in the treatment and presentation of achiral non-centrosymmetric crystal structures.

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Liu, Wu, Qiu Li, Gang Jin, and Wei Qiu. "Measurement of the Euler Angles of Wurtzitic ZnO by Raman Spectroscopy." Journal of Spectroscopy 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/6430540.

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A Raman spectroscopy-based step-by-step measuring method of Euler angles φ,θ,and ψ was presented for the wurtzitic crystal orientation on a microscopic scale. Based on the polarization selection rule and coordinate transformation theory, a series of analytic expressions for the Euler angle measurement using Raman spectroscopy were derived. Specific experimental measurement processes were presented, and the measurement of Raman tensor elements and Euler angles of the ZnO crystal were implemented. It is deduced that there is a trigonometric functional relationship between the intensity of each Raman bands of wurtzite crystal and Euler angle ψ, the polarization direction of incident light under different polarization configurations, which can be used to measure the Euler angles. The experimental results show that the proposed method can realize the measurement of Euler angles for wurtzite crystal effectively.

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3

Sink, Joseph, and Craig Pryor. "Empirical tight-binding parameters for wurtzite group III–V(non-nitride) and IV materials." AIP Advances 13, no. 2 (February 1, 2023): 025354. http://dx.doi.org/10.1063/5.0129007.

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Suitable tight-binding models for wurtzite III–V (non-nitride) and group-V materials are presently missing in the literature. Many commonly used nearest neighbor tight-binding models for cubic-zincblende semiconductors result in highly inaccurate band structures when transferred to hexagonal polytypes. Wurtzite parameters would be of use in modeling nanowires that primarily condense into either wurtzite or zincblende crystal phases. Nanowire growth has seen significant development over the last decade, and polytypic heterostructures are now able to be fabricated. We have produced a set of spds* tight-binding parameters to be used in the hexagonal-wurtzite crystal phase for non-nitride III–V and group V semiconductors. We confine our parameter space to remain in the vicinity of a well-established zincblende parameter set to ensure semi-transferability between the wurtzite and zincblende polytypes. Our wurtzite parameters, when combined with the existing zincblende parameters, enable modeling electronic structures of heterostructures containing both the wurtzite and zincblende crystal phases.

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Sana, Prabha, Shammi Verma, and M. M. Malik. "Optical and Structural Investigations of Manganese Doped ZnS/SiO2 Core-Shell Nanostructure." International Journal of Nanoscience 14, no. 03 (May 19, 2015): 1550006. http://dx.doi.org/10.1142/s0219581x15500064.

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The paper reports room temperature synthesis of wurtzite type manganese doped ZnS nanostructures via colloidal technique. The reaction procedure found to play an important role in the crystal growth of ZnS . Surface encapsulation of ZnS by silica ( SiO 2) provides effective approach for uniform coating, where 3-Mercaptopropyl Tri methoxysilane (MPS) has been used for silica source as a capping molecule. The obtained silica coated ZnS nanocrystals were well dispersed with hexagonal wurtzite structure of core-shell particles size of about 15 nm. Aggregation of these nanoparticles has been promoted to special shaped structures, which are crystals of 8H wurtzite with prominent pyramidal morphology with curved faces. Growth phenomena of this wurtzite polytype of homologous series 8H is based on screw dislocations and exhibited optimal photoluminescence (PL) spectra.

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Saleem, Samra, Ammara Maryam, Kaneez Fatima, Hadia Noor, Fatima Javed, and Muhammad Asghar. "Phase Control Growth of InAs Nanowires by Using Bi Surfactant." Coatings 12, no. 2 (February 15, 2022): 250. http://dx.doi.org/10.3390/coatings12020250.

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To realize practical applications of nanowire-based devices, it is critical, yet challenging, to control crystal structure growth of III-V semiconductor nanowires. Here, we demonstrate that controlled wurtzite and zincblende phases of InAs nanowires can be fabricated using bismuth (Bi) as a surfactant. For this purpose, catalyst free selective area epitaxial growth of InAs nanowires was performed using molecular beam epitaxy (MBE). During the growth, Bi was used which may act as a wetting agent influencing the surface energy at growth plane ends, promoting wurtzite crystal phase growth. For a demonstration, wurtzite and zincblende InAs nanowires were obtained with and without using Bi-flux. Photoluminescence spectroscopy (PL) analysis of the nanowires indicates a strong correlation between wurtzite phase and the Bi-flux. It is observed that the bandgap energy of wurtzite and zincblende nanowires are ∼0.50 eV and ∼0.42 eV, respectively, and agree well with theoretical estimated bandgap of corresponding InAs crystal phases. A blue shift in PL emission peak energy was found with decreasing nanowire diameter. The controlled wurtzite and zincblende crystal phase and its associated heterostructure growth of InAs nanowires on Si may open up new opportunities in bandgap engineering and related device applications integrated on Si. Furthermore, this work also illustrates that Bi as a surfactant could play a dynamic role in the growth mechanism of III-V compound semiconductors.

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Ross, Jennifer, Mike Rubin, and T. K. Gustafson. "Single crystal wurtzite GaN on (111) GaAs with AlN buffer layers grown by reactive magnetron sputter deposition." Journal of Materials Research 8, no. 10 (October 1993): 2613–16. http://dx.doi.org/10.1557/jmr.1993.2613.

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We report the growth conditions necessary for highly oriented wurtzite GaN films on (111) GaAs, and single crystal GaN films on (111) GaAs using AlN buffer layers. The GaN films and AlN buffers are grown using rf reactive magnetron sputter deposition. Oriented basal plane wurtzite GaN is obtained on (111) GaAs at temperatures between 550 and 620 °C. However, using a high temperature 200 Å AlN buffer layer epitaxial GaN is produced. Crystal structure and quality are measured using x-ray diffraction (XRD), reflection electron diffraction (RED), and a scanning electron microscope (SEM). This is the first report of single crystal wurtzite GaN on (111) GaAs using AlN buffer layers by any growth technique. Simple AlN/GaN heterostructures grown by rf reactive sputter deposition on (111) GaAs are also demonstrated.

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Ma, Yan, Jikang Jian, Rong Wu, Yanfei Sun, and Jin Li. "Preparation of CdTe nanostructures with different crystal structures and morphologies." Powder Diffraction 26, S1 (December 2011): S47—S50. http://dx.doi.org/10.1154/1.3662023.

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CdTe nanorods and various branched nanostructures with different crystal structures were have successfully prepared via the catalyst-assisted vacuum thermal evaporation (CVTE) technique using various experimental parameters. SEM and XRD studies were carried out on the as-prepared CdTe nanostructures. The results show that the morphologies and crystal structures of the products were strongly influenced by the growth conditions and the mole ratios of Bi and CdTe. In the high mole ratio (0.08:1) of Bi and CdTe, CdTe branched nanostructures of CdTe were obtained, while nanorods of CdTe were formed at a lower mole ratio of 0.05:1. The crystal structure of products is either Zinc blende or a two-phase mixture of zinc blende and wurtzite. The content of the wurtzite phase were found to increase with increasing growth temperature. Our results also reveal that high growth temperature tends to form the wurtzite phase, and stacking faults may exist in materials grown in higher temperatures. These nanostructures grow following the vapor–liquid–solid (VLS) mechanism.

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8

Volcheck, V. S., M. S. Baranava, and V. R. Stempitsky. "Thermal conductivity of wurtzite gallium nitride." Proceedings of the National Academy of Sciences of Belarus, Physical-Technical Series 67, no. 3 (October 8, 2022): 285–97. http://dx.doi.org/10.29235/1561-8358-2022-67-3-285-297.

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This paper reviews the theoretical and experimental works concerning one of the most important parameters of wurtzite gallium nitride – thermal conductivity. Since the heat in gallium nitride is transported almost exclusively by phonons, its thermal conductivity has a temperature behavior typical of most nonmetallic crystals: the thermal conductivity increases proportionally to the third power of temperature at lower temperatures, reaches its maximum at approximately 1/20 of the Debye temperature and decreases proportionally to temperature at higher temperatures. It is shown that the thermal conductivity of gallium nitride (depending on fabrication process, crystallographic direction, concentration of impurity and other defects, isotopical purity) varies significantly, emphasizing the importance of determining this parameter for the samples that closely resemble those being used in specific applications. For isotopically pure undoped wurtzite gallium nitride, the thermal conductivity at room temperature has been estimated as high as 5.4 W/(cm·K). The maximum room temperature value measured for bulkshaped samples of single crystal gallium nitride has been 2.79 W/(cm·K).

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9

Pavlov, Alexander, Alexey Mozharov, Yury Berdnikov, Camille Barbier, Jean-Christophe Harmand, Maria Tchernycheva, Roman Polozkov, and Ivan Mukhin. "DFT analysis of crystal polarity on graphene surface." Journal of Physics: Conference Series 2015, no. 1 (November 1, 2021): 012105. http://dx.doi.org/10.1088/1742-6596/2015/1/012105.

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Abstract We report an ab-initio study of the preferred polarity for wurtzite GaN nanostructures on virtual graphene substrates. By means of the density functional theory analysis we show that N-polar nanostructures on graphene are energetically favorable in comparison to Ga-polar. These finding are in agreement with experimentally observed N-polarity of wurtzite GaN nanowires grown on graphene substrate. We believe that the revealed polarity preference is of importance for piezoelectric and optoelectronic device design.

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10

Chen, Chunlin, Deqiang Yin, Takeharu Kato, Takashi Taniguchi, Kenji Watanabe, Xiuliang Ma, Hengqiang Ye, and Yuichi Ikuhara. "Stabilizing the metastable superhard material wurtzite boron nitride by three-dimensional networks of planar defects." Proceedings of the National Academy of Sciences 116, no. 23 (May 17, 2019): 11181–86. http://dx.doi.org/10.1073/pnas.1902820116.

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Wurtzite boron nitride (w-BN) is a metastable superhard material that is a high-pressure polymorph of BN. Clarifying how the metastable high-pressure material can be stabilized at atmospheric pressure is a challenging issue of fundamental scientific importance and promising technological value. Here, we fabricate millimeter-size w-BN bulk crystals via the hexagonal-to-wurtzite phase transformation at high pressure and high temperature. By combining transmission electron microscopy and ab initio molecular dynamics simulations, we reveal a stabilization mechanism for w-BN, i.e., the metastable high-pressure phase can be stabilized by 3D networks of planar defects which are constructed by a high density of intersecting (0001) stacking faults and {101¯0} inversion domain boundaries. The 3D networks of planar defects segment the w-BN bulk crystal into numerous nanometer-size prismatic domains with the reverse crystallographic polarities. Our findings unambiguously demonstrate the retarding effect of crystal defects on the phase transformations of metastable materials, which is in contrast to the common knowledge that the crystal defects in materials will facilitate the occurrence of phase transformations.

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Verma, Prabhat, and A. Yamada. "Raman Scattering from Wurtzite GaN Bulk Crystal." Materials Science Forum 389-393 (April 2002): 1501–4. http://dx.doi.org/10.4028/www.scientific.net/msf.389-393.1501.

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Leiro, J. A., M. H. Heinonen, S. S. Granroth, T. T. Laiho, and A. Szczerbakow. "Characterization of wurtzite CdSe single crystal surfaces." Journal of Physics and Chemistry of Solids 75, no. 5 (May 2014): 624–28. http://dx.doi.org/10.1016/j.jpcs.2014.01.007.

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13

Harafuji, K., T. Tsuchiya, and K. Kawamura. "Magnesium diffusion in wurtzite-type GaN crystal." physica status solidi (c), no. 7 (December 2003): 2240–43. http://dx.doi.org/10.1002/pssc.200303298.

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Harafuji, K., T. Tsuchiya, and K. Kawamura. "Melting point of wurtzite-type GaN crystal." physica status solidi (c), no. 7 (December 2003): 2420–23. http://dx.doi.org/10.1002/pssc.200303476.

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15

ZHANG, L. "POLAR INTERFACE-OPTICAL VIBRATIONAL SPECTRA IN A WURTZITE GaN/AlN RECTANGULAR QUANTUM WIRE." Surface Review and Letters 13, no. 01 (February 2006): 75–80. http://dx.doi.org/10.1142/s0218625x0600786x.

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Under the dielectric continuum model and Loudon's uniaxial crystal model, the interface optical (IO) phonon modes in a quasi-one-dimensional (Q1D) wurtzite rectangular quantum wire are deduced and analyzed. Numerical calculation on a wurtzite GaN/AlN rectangular wurtzite quantum wire was performed. Results reveal that the dispersion frequencies of IO modes sensitively depend on the geometric structures of the Q1D wurtzite rectangular quantum wires. The degenerating behavior of the IO phonon modes in the Q1D wurtzite rectangular quantum wire has been clearly observed for small free wave number kz in z-direction. The limited frequency behaviors of IO modes have been analyzed deeply, and detailed comparisons with those in wurtzite planar quantum wells and cylindrical quantum wires are also done. Moreover, once the anisotropy of the wurtzite material has been ignored, the present theories can be naturally reduced to the situation of Q1D cubic rectangular quantum wire systems.

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16

Ambacher, O., S. Mihalic, E. Wade, M. Yassine, A. Yassine, N. Feil, and B. Christian. "Influence of alloying and structural transition on the directional elastic and isotropic thermodynamic properties of wurtzite and layered hexagonal Sc_xAl_1−xN crystals." Journal of Applied Physics 132, no. 17 (November 7, 2022): 175101. http://dx.doi.org/10.1063/5.0120141.

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The structural, elastic, and basic thermodynamic properties of hexagonal Sc xAl1−xN crystals are calculated and discussed over the whole range of possible random alloys, including the transition from wurtzite to the layered hexagonal structure. Based on a review of lattice and internal parameters in combination with complete datasets of stiffness coefficients published in the literature, differing in the considered alloying intervals and the predicted structural transitions, changes in the crystal lattices caused by the substitution of aluminum by scandium atoms are discussed and illustrated. Crystal properties like the mass densities, average bond angles, and bond lengths are calculated, and the compliance coefficients, Young's modulus, shear modulus, Poisson's ratio, compressibility, and sound velocities are determined depending on the alloy composition and in relation to the orientation of crystal planes and axes. Particular attention is paid to the occurring directional anisotropies and the changes in structural and elastic properties in the alloy region of the structural transition between wurtzite and layered hexagonal Sc xAl1−xN crystals. The acoustic velocities determined are used to calculate basic thermodynamic properties such as the Debye temperature, heat capacity, and minimum heat conduction, as well as to evaluate both the influence of the alloying and the structural transition on these properties.

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17

Wu, Xi, Hongcheng Wang, Dongxiong Ling, Chuanyu Jia, Wei Lü, Ye Liu, Fei Zhou, and Zhenrong Li. "Synthesis of GaN Crystals by Nitrogen Pressure-Controlled Recrystallization Technique in Na Alloy Melt." Crystals 11, no. 9 (September 2, 2021): 1058. http://dx.doi.org/10.3390/cryst11091058.

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GaN crystals are synthesized by recrystallization technique in Na-Li-Ca alloy melt under different N2 pressure. X-ray powder diffraction results confirm that the structure of crystals is GaN with wurtzite type and there still have raw powders remaining. The total mass of GaN decreases with the nitrogen pressure reduces. No GaN crystals are found in the solution under N2 pressure of 0.4 MPa. The morphologies of the crystal are mainly prism and pyramid. The size of the crystal increases when closer to the liquid surface. Raman spectra indicates that these crystals are stress-free and crystal grown at 3.6 MPa has high structural quality or low impurity concentrations. The results reveal that the solubility and supersaturation of the solution are controlled by N2 pressure. The principle of GaN crystal synthesis by recrystallization is discussed.

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Cheiwchanchamnangij, Tawainan, Thomas Birkel, Walter R. L. Lambrecht, and Al L. Efros. "GaAs Nanowires: A New Place to Explore Polytype Physics." Materials Science Forum 717-720 (May 2012): 565–68. http://dx.doi.org/10.4028/www.scientific.net/msf.717-720.565.

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Recently, polytypism has been observed in nanowires in materials, for which normally only one crystal structure is stable. For example, GaAs, nanowires can have wurtzite or mixed zincblende/wurtzite. Here we provide band structure parameters for wurzite and 4H GaAs and use them for modeling the nanowire electronic states. The band gap, crystal field splitting, and its strain dependence, as well as the effective mass parameters are calculated using the quasiparticle self-consistent GW method. The nanowire electronic states are obtained in the envelope function approximation within a simplified cylindrical model. The crystal field splitting of the wurtzite GaAs valence band is found to be 180 meV while in 4H-GaAs it is less than half 69 meV, suggesting a downward bowing as function of hexagonality. The conduction band minimum at Γ changes symmetry character under strain. We discuss the consequences for nanowires and determine the conditions under which a polarization reversal of photoluminescence can occur from mostly perpendicular to parallel to the wire.

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19

Satoh, Shiro, Koichi Ohtaka, Takehito Shimatsu, and Shuji Tanaka. "Crystal structure deformation and phase transition of AlScN thin films in whole Sc concentration range." Journal of Applied Physics 132, no. 2 (July 14, 2022): 025103. http://dx.doi.org/10.1063/5.0087505.

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This article reports lattice deformation and phase transition of AlScN thin films in the whole composition. AlScN films were deposited on Pt/Ta/SiO2/Si substrates by direct current magnetron reactive sputtering with Al and Sc targets. At Sc concentration up to 30%, AlScN has a wurtzite structure with piezoelectricity. Transition from a wurtzite phase to a two-phase mixture happens between 30% and 35% Sc concentration, and transition from a two-phase mixture to a cubic phase happens between 38% and 43% Sc concentration. The wurtzite structure gradually deforms with the decrease in lattice constant c from 16% to 35% Sc concentration. Lattice constant c at 38% Sc in the two-phase mixture region is larger than that of 35% Sc concentration. These increases mean that distortion of c axis for the wurtzite structure over 35% Sc concentration in the two-phase mixture region is considered to be released and/or eased due to the appearance of the cubic phase, and that Sc concentration of the wurtzite phase to be smaller and that of the cubic phase larger than the film composition measured by energy-dispersive x-ray spectroscopy and Rutherford backscattering spectroscopy. At higher Sc concentration up to 43%, the remained wurtzite phases are replaced by non-piezoelectric cubic phases, and the cubic structure approaches the rock-salt structure of ScN with a further increase in Sc concentration.

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20

Solozhenko, Vladimir L., and Samir F. Matar. "Polymorphism of boron phosphide: theoretical investigation and experimental assessment." Journal of Materials Chemistry C 10, no. 10 (2022): 3937–43. http://dx.doi.org/10.1039/d2tc00363e.

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Stable crystal structures of wurtzite and recently discovered rhombohedral polymorphs of boron phosphide were obtained based on crystal chemistry rationale and unconstrained geometry optimization calculations within density functional theory.

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Chamard, Virginie, Julian Stangl, Stephane Labat, Bernhard Mandl, Rainer T. Lechner, and Till H. Metzger. "Evidence of stacking-fault distribution along an InAs nanowire using micro-focused coherent X-ray diffraction." Journal of Applied Crystallography 41, no. 2 (March 8, 2008): 272–80. http://dx.doi.org/10.1107/s0021889808001167.

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InAs nanowire samples grown by metal-organic chemical vapor deposition present a significant amount of wurtzite structure, while the zincblende lattice is known to be the stable crystal structure for the bulk material. The question of the wurtzite distribution in the sample is addressed using phase-sensitive coherent X-ray diffraction with a micro-focused beam at a synchrotron source. The simultaneous investigation of the wurtzite 10\bar{1}0, 20\bar{2}0 and 30\bar{3}0 reflections performed on a bunch of single wires shows unambiguously that the wurtzite contribution is a result of stacking faults distributed along the wire. Additional simulations lead to adjustments of the wire structural parameters, such as the wurtzite content, the strain distribution, the wire diameters and their respective orientations.

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WEI, SHU YI, FANG ZHANG, WEI LI, ZU ZHAO, and WEN DENG HUANG. "ELECTRON–PHONON INTERACTION IN WURTZITE AlxGa1-xN TERNARY CRYSTAL." International Journal of Modern Physics B 21, no. 22 (September 10, 2007): 3841–50. http://dx.doi.org/10.1142/s0217979207037740.

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Optical vibrations of the lattice and the electron-optical-phonon interaction in wurtzite ternary nitride-based crystals was studied using the pseudo-unit-cell approach. The Fröhlich coupling constants, polaron energy shifts and the effective masses of the polaron in the system were investigated using the perturbation method. It was found that the LO and TO phonons in wurtzite Al x Ga 1-x N exhibit the one-mode behavior. The effects of the unit-cell volume varying with the composition x of ternary nitride-based crystals were also investigated.

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Il’ves, V. G., and S. Yu Sokovnin. "Structural and Magnetic Properties of Nanopowders and Coatings of Carbon-Doped Zinc Oxide Prepared by Pulsed Electron Beam Evaporation." Journal of Nanotechnology 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/4628193.

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With the help of electron beam evaporation of mechanical mixtures of nonmagnetic micron powders ZnO and carbon in vacuum with the subsequent annealing of evaporation products in air at the temperature of 773 K, single-phase crystal nanopowders ZnO-C were produced with the hexagonal wurtzite structure and low content of the carbon dopant not exceeding 0.25 wt%. It was established that doping ZnO with carbon stimulates primary growth of nanoparticles along the direction 0001 in the coatings. Nanocrystal growth in coatings occurs in the same way as crystal growth in thin films, with growth anisotropy in the c-axis direction in wurtzite ZnO. Element mapping has confirmed homogeneous distribution of carbon in ZnO lattice. Ferromagnetism of single-phase crystal nanopowders ZnO-C with the hexagonal wurtzite structure and low content of the carbon dopant not exceeding 0.25 wt% was produced at room temperature. Ferromagnetic response of the doped NP ZnO-C has exceeded the ferromagnetic response of pure NP ZnO 5 times. The anhysteretic form of magnetization curves NP ZnO-C indicates aspiration of samples to superparamagnetism manifestation.

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Zhang, Li, and J. J. Shi. "Polar optical phonon states and their degenerative behaviors of wurtziteZnO/MgZnOcoupling quantum dots." International Journal of Modern Physics B 28, no. 11 (March 26, 2014): 1430005. http://dx.doi.org/10.1142/s0217979214300059.

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Analytical polar optical phonon states in a wurtzite ZnO -based cylindrical coupling quantum dots (CQDs) with arbitrary number of quantum dots (QDs) are deduced and analyzed. It is found that there are four types of polar mixing optical phonon modes, i.e., the z-IO/ρ-QC modes, the z-PR/ρ-IO modes, the z-QC/ρ-QC modes and the z-HS/ρ-IO modes coexisting in the ZnO -based CQDs. Within the framework of the macroscopic dielectric continuum model, the dispersive equations are derived by using the transferring matrix method. And the Fröhlich electron–phonon interaction Hamiltonians are obtained via a standard procedure of field quantization. The relationships between the present ZnO -based CQDs and the ZnO -based quantum wells (QWs) or the nanowires (NWs) are analyzed, and the general features of phonon modes in ZnO -based low-dimensional quantum structures are concluded and discussed. Under certain conditions, the present theoretical results in wurtzite ZnO -based CQDs can be naturally degenerate into those in wurtzite ZnO -based single or double QDs, wurtzite NWs and QWs and even into cubic quantum confined structures. This just embodies the intrinsic consistency of phonon mode theories in low-dimensional confined systems with different confined dimensions. Due to the ternary mixing effect of MgxZn1-xO crystal, the dielectric functions of MgxZn1-xO crystals are quite complicated, and the phonon modes in ZnO -based quantum structures have both the features of phonon modes in anisotropic wurtzite confined systems and isotropic rock-salt crystal quantum systems. The characteristics of electron–phonon coupling strength in ZnO -based quantum systems are summarized. Very strong polaronic effect could be prognosticated and anticipated in ZnO -based low-dimensional quantum structures because of their quite large electron–phonon coupling constants. The theoretical results and conclusions described in this paper also can be looked on as a summary of phonon states and their general features in ZnO -based quantum confined systems.

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Gorji Ghalamestani, Sepideh, Sebastian Lehmann, and Kimberly A. Dick. "Can antimonide-based nanowires form wurtzite crystal structure?" Nanoscale 8, no. 5 (2016): 2778–86. http://dx.doi.org/10.1039/c5nr07362f.

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Han, Yanbing, Aaron M. Holder, Sebastian Siol, Stephan Lany, Qun Zhang, and Andriy Zakutayev. "Zinc-Stabilized Manganese Telluride with Wurtzite Crystal Structure." Journal of Physical Chemistry C 122, no. 32 (July 23, 2018): 18769–75. http://dx.doi.org/10.1021/acs.jpcc.8b05233.

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Chen, Gui-chu, and Guang-han Fan. "Zone-center optical phonons in wurtzite InAlN crystal." Optoelectronics Letters 7, no. 5 (September 2011): 394–96. http://dx.doi.org/10.1007/s11801-011-1006-y.

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Panyajirawut, Pongladda, Kanokwan Thongruanhmuan, Banthita Aimanee, Sirirat Phonphithak, and Thitima Charumkhruea. "ZnO Doped with Fe and Mn Prepared by Sol-Gel Method." Advanced Materials Research 1131 (December 2015): 64–68. http://dx.doi.org/10.4028/www.scientific.net/amr.1131.64.

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ZnO doped with iron (Fe) and manganese (Mn) were prepared by sol-gel method. The precursors for Fe-doped ZnO were zinc acetate and iron nitrate while those for Mn-doped ZnO were zinc nitrate and manganese nitrate. Crystal structures were characterized by means of XRD. The XRD patterns suggest the crystals are hexagonal wurtzite. Furthermore, the magnetic properties were studied by VSM. The hysteresis loops correspond to paramagnetism.

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Zheng, Wen Li, and Wei Yang. "Hydrothermal Synthesis of Diluted Magnetic Zn_1-xMn_xO Semiconductor." Applied Mechanics and Materials 313-314 (March 2013): 184–87. http://dx.doi.org/10.4028/www.scientific.net/amm.313-314.184.

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Diluted magnetic semiconductor Zn1-xMnxO crystals were synthesized at 430°C for 24h by hydrothermal method. 3mol·L-1KOH was used as the mineralizer, and the fill factor is 35%. The obtained crystals show a ZnO wurtzite structure, with positive polar faces{0001}, negative polar faces{000 },pfaces{ 011} and–pfaces { 01 } exposed. The height of the crystal is 5-30 m and radius-height ratio is2:1. Mn atom concentration of 2. 6% (x=0.026) was determined using X-ray energy dispersive spectroscopy ( EDS). The crystals show low-temperature ferromagnetism with Curie temperature of 50K.

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Yu, Chao, Linlin Zhang, Long Tian, Dan Liu, Fanglin Chen, and Cheng Wang. "Synthesis and formation mechanism of CuInS2 nanocrystals with a tunable phase." CrystEngComm 16, no. 41 (2014): 9596–602. http://dx.doi.org/10.1039/c4ce00893f.

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Kar, Soumitra, Swadeshmukul Santra, and Subhadra Chaudhuri. "Direct Synthesis of ZnS Nanoribbons, Micro-Sheets and Tetrapods." Journal of Nanoscience and Nanotechnology 8, no. 6 (June 1, 2008): 3222–27. http://dx.doi.org/10.1166/jnn.2008.150.

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ZnS nano and micro structures such as nanoribbons, large sheets and tetrapod shaped crystals were fabricated by direct thermal evaporation of ZnS powder without using any catalyst. Formation of the one dimensional structures such as nanoribbons and micron order sheets was attributed to the vapor-solid growth mechanism. The formation of octahedron nucleus with cubic crystal structures was proposed as the growth unit of the wurtzite crystal structured tetrapods. Appearance of the periodic stacking faults or twining planes in between alternate cubic and hexagonal crystal structured zones along the growth direction of the ribbons provided secondary growth sites for the octahedron nucleus and subsequent crystal growth resulted in to the formation of the tetrapod arrays. These nano/micro structures of ZnS exhibited a green emission band at room temperature.

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McKernan, Stuart, and C. Barry Carter. "Polarity Determination in Sphalerite and Wurtzite Structures." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 2 (August 12, 1990): 500–501. http://dx.doi.org/10.1017/s0424820100136106.

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The determination of the absolute polarity of a polar material is often crucial to the understanding of the defects which occur in such materials. Several methods exist by which this determination may be performed. In bulk, single-domain specimens, macroscopic techniques may be used, such as the different etching behavior, using the appropriate etchant, of surfaces with opposite polarity. X-ray measurements under conditions where Friedel’s law (which means that the intensity of reflections from planes of opposite polarity are indistinguishable) breaks down can also be used to determine the absolute polarity of bulk, single-domain specimens. On the microscopic scale, and particularly where antiphase boundaries (APBs), which separate regions of opposite polarity exist, electron microscopic techniques must be employed. Two techniques are commonly practised; the first [1], involves the dynamical interaction of hoLz lines which interfere constructively or destructively with the zero order reflection, depending on the crystal polarity. The crystal polarity can therefore be directly deduced from the relative intensity of these interactions.

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Lin, Yin-Pai, Sergei Piskunov, Laima Trinkler, Mitch Ming-Chi Chou, and Liuwen Chang. "Influence of Stress on Electronic and Optical Properties of Rocksalt and Wurtzite MgO–ZnO Nanocomposites with Varying Concentrations of Magnesium and Zinc." Nanomaterials 12, no. 19 (September 28, 2022): 3408. http://dx.doi.org/10.3390/nano12193408.

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The structural, electronic and optical properties of stressed MgO–ZnO nanocomposite alloys with concentrations of Zn and Mg varying from 0.125 to 0.875 were studied using ab initio simulations. Two crystal structures are considered for the initial MgO–ZnO alloys: the rocksalt Mg\({_\text{1-x}}\)Zn\({_\text{x}}\)O and wurtzite Zn\({_\text{1-x}}\)Mg\({_\text{x}}\)O phases. For rocksalt Mg\({_\text{1-x}}\)Zn\({_\text{x}}\)O, the optimized structures are stable at pressures below 10 GPa. The larger the Mg concentration and pressure, the wider the \({E_{g}}\) of the rocksalt phase. In contrast, the optimal geometries of wurtzite Zn\({_\text{1-x}}\)Mg\({_\text{x}}\)O reveal a diversity of possibilities, including rocksalt, wurtzite and mixed phases. These effects lead to the fact that the optical properties of wurtzite Zn\({_\text{1-x}}\)Mg\({_\text{x}}\)O not only demonstrate the properties of the wurtzite phase but also indicate the optical features of the rocksalt phase. In addition, mixed phases of Zn\({_\text{1-x}}\)Mg\({_\text{x}}\)O simultaneously provide the characteristics of both wurtzite and rocksalt phases with the same structures in different dielectric matrices.

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Oktyabrsky, S., K. Dovidenko, A. K. Sharma, V. Joshkin, and J. Narayan. "CRYSTAL STRUCTURE AND DEFECTS IN NITROGEN-DEFICIENT GaN." MRS Internet Journal of Nitride Semiconductor Research 4, S1 (1999): 709–14. http://dx.doi.org/10.1557/s109257830000329x.

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We have studied crystal structure and associated defects in GaN films grown on sapphire under nitrogen-deficient conditions by metalorganic chemical vapor deposition (MOCVD) and pulsed laser deposition (PLD). The structural quality of the PLD films grown at 750 °C was comparable with those grown by MOCVD at 1050 °C having threading dislocations density of about 1010 cm−2 at a film thickness 150-200 nm. Microstructure of the PLD films grown at temperatures above 780°C was found to be similar to that of nitrogen-deficient MOCVD films indicating the loss of nitrogen due to thermal decomposition of the nitride layers. Nitrogen-deficient MOCVD and PLD films exhibit polycrystalline structure with a mixture of cubic zinc-blende and wurtzite hexagonal GaN grains retaining tetragonal bonding across the boundaries and hence the epitaxial orientations and polarity. Renucleation of the wurtzite phase at different {111} planes of cubic GaN results in a rough and faceted surface of the film. Most of the stoichiometric films displayed (0001) Ga-face polarity, but the renucleated inclined wurtzite grains grew in the opposite N-face polarity. The major defects related to the cubic structural metastability are stacking faults and microtwins which being nuclei of the metastable cubic phase have an extremely low energy. We elucidate that the cubic phase is more stable under the nitrogen deficiency and, therefore, can exist without decomposition at higher nitrogen vacancy concentrations in the material.

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Hiraya, Yoshihiro, Fumiya Ishizaka, Katsuhiro Tomioka, and Takashi Fukui. "Crystal phase transition to green emission wurtzite AlInP by crystal structure transfer." Applied Physics Express 9, no. 3 (February 3, 2016): 035502. http://dx.doi.org/10.7567/apex.9.035502.

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Li, Yan, Yun Ling Zou, and Yan Yan Hou. "Synthesis and Characterization of Missile-Like ZnO." Advanced Materials Research 236-238 (May 2011): 2183–86. http://dx.doi.org/10.4028/www.scientific.net/amr.236-238.2183.

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A novel missile-like ZnO structure has been synthesized solvo-thermally in absolute alcohol using Zn(NO3)2·6H2O and NaOH as starting materials, and characterized by Scanning Electron Microscopy, powder X-ray diffraction and room temperature photoluminescence. The missile-like ZnO crystal, with a wurtzite structure and a blue-green emission at 459 nm, is made up of two symmetrical rocket-like crystals possessing a prismatic base and a hexagonal pyramid linking with each other along plane (0001(_)).

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Zheng, Wen Li, and Wei Yang. "Diluted Magnetic Zn_1-XMn_xO Semiconductor Synthesized by Hydrothermal Method." Applied Mechanics and Materials 271-272 (December 2012): 26–30. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.26.

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Diluted magnetic semiconductor Zn1-xMnxO crystals were synthesized at 430°C for 24h by hydrothermal method. 3mol·L-1KOH was used as the mineralizer, and the fill factor is 35%. The obtained crystals show a ZnO wurtzite structure, with positive polar faces{0001}, negative polar faces{000 }, p faces{ 011} and –p faces { 01 } exposed. The height of the crystal is 5-30 m and radius-height ratio is2:1. Mn atom concentration of 2. 6% (x=0.026) was determined using X-ray energy dispersive spectroscopy ( EDS). The crystals show low-temperature ferromagnetism with Curie temperature of 50K.

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Namazi, Luna, Malin Nilsson, Sebastian Lehmann, Claes Thelander, and Kimberly A. Dick. "Selective GaSb radial growth on crystal phase engineered InAs nanowires." Nanoscale 7, no. 23 (2015): 10472–81. http://dx.doi.org/10.1039/c5nr01165e.

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Wang, Hsuan I., Wei Tsung Tang, Li Wei Liao, Pei Shan Tseng, Chih Wei Luo, Chu Shou Yang, and Takayoshi Kobayashi. "Femtosecond Laser-Induced Formation of Wurtzite Phase ZnSe Nanoparticles in Air." Journal of Nanomaterials 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/278364.

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We demonstrate an effective method to prepare wurtzite phase ZnSe nanoparticles from zincblende ZnSe single crystal using femtosecond pulse laser ablation. The fabricated ZnSe nanoparticles are in spherical shape and uncontaminated while synthesized under ambient environment. By controlling the laser fluences, the average size of ZnSe nanoparticles can be varied from~16 nm to~22 nm in diameter. In Raman spectra, the surface phonon mode becomes dominant in the smaller average particle size with uniform size distribution. The interesting phase transition from the zinc blende structure of ZnSe single crystal to wurtzite structure of ZnSe nanoparticles may have been induced by the ultrahigh ablation pressure at the local area due to the sudden injection of high energy leading to solid-solid transition.

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Benkrima, Y., A. Souigat, Z. Korichi, and M. E. Soudani. "Structural and optical properties of Wurtzite phase MgO: first principles calculation." Digest Journal of Nanomaterials and Biostructures 17, no. 4 (November 1, 2022): 1211–22. http://dx.doi.org/10.15251/djnb.2022.174.1211.

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The pseudo ab initio ability is based on density function theory (DFT), use of generalized gradient approximation (GGA), local density approximation (LDA).We use of the Siesta symbol for the first time in studying this particular compound and the wurtzite phase that enabled us to find the structural and optical properties of MgO in its crystal structure (B4) wurtzite. Where the structural results indicated that the wurtzite phase has lattice constants very close to what was found previously in applied studies, and all the calculated properties such as absorption coefficient, reflectivity, extinction, refractive index, imaginary and real part of the constant show that the dielectric has an energy gap greater than 3.27 eV, meaning that it can be used in applications in the ultraviolet (UV) region, and all properties calculated by approximation (GGA) give slightly better results than the use case approximation (LDA).The results obtained when we study the compound MgO wurtzite are a reference for further theoretical and experimental studies.

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KARLSSON, LISA S., MAGNUS W. LARSSON, JAN-OLLE MALM, L. REINE WALLENBERG, KIMBERLY A. DICK, KNUT DEPPERT, WERNER SEIFERT, and LARS SAMUELSON. "CRYSTAL STRUCTURE OF BRANCHED EPITAXIAL III–V NANOTREES." Nano 01, no. 02 (September 2006): 139–51. http://dx.doi.org/10.1142/s1793292006000203.

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In this review we discuss the morphology and crystal structure of branched epitaxial III–V semiconductor structures, so called nanotrees, based on our own work with GaP , InAs and GaP/InP . These structures are formed by epitaxial growth in a step-wise procedure where each level can be individually controlled in terms of diameter, length and composition. Poly-typism is commonly observed for III–Vs with zinc blende, wurtzite or combinations thereof as the resulting crystal structure. Here we review GaP as an example of zinc blende and InAs of wurtzite type of growth in terms of nanotrees with two to three levels of growth. Included are also previously unpublished results on the growth of GaP/InP nanotrees to demonstrate effects of heteroepitaxial growth with substantial mismatch. For these structures a topotaxial growth behavior was observed with InP wires crawling along or spiraling around the GaP nanowires acting as a free-standing substrates.

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Pedesseau, L., J. Even, M. Modreanu, D. Chaussende, E. Sarigiannidou, O. Chaix-Pluchery, and O. Durand. "Al4SiC4 wurtzite crystal: Structural, optoelectronic, elastic, and piezoelectric properties." APL Materials 3, no. 12 (December 2015): 121101. http://dx.doi.org/10.1063/1.4936667.

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Harafuji, Kenji, and Katsuyuki Kawamura. "Magnesium Diffusion at Dislocation in Wurtzite-Type GaN Crystal." Japanese Journal of Applied Physics 44, no. 9A (September 8, 2005): 6495–504. http://dx.doi.org/10.1143/jjap.44.6495.

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Lee, S. C., S. S. Ng, K. G. Saw, Z. Hassan, and H. Abu Hassan. "Surface phonon polariton characteristics of bulk wurtzite ZnO crystal." Physica B: Condensed Matter 406, no. 1 (January 2011): 115–18. http://dx.doi.org/10.1016/j.physb.2010.10.036.

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Mukherjee, Prabir K., Subrat K. Shadangi, and Gouri S. Tripathi. "Pressure dependence of elastic properties of wurtzite ZnO crystal." Phase Transitions 92, no. 9 (August 5, 2019): 798–805. http://dx.doi.org/10.1080/01411594.2019.1650932.

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Pezoldt, Jörg, and Andrei Alexandrovich Kalnin. "Wurtzite SiC Formation in Plastic Deformed 3C and 6H." Materials Science Forum 1004 (July 2020): 243–48. http://dx.doi.org/10.4028/www.scientific.net/msf.1004.243.

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Single side clamped 3C and 6H single crystal silicon carbide beams were elastic deformed using a special designed deformation stage in an electron microscope and subjected to high temperatures. The structural transitions occurring during the plastic relaxation process were recorded in situ in the electron microscope using reflection high energy electron diffraction in {110} azimuthal direction. For both polytypes, a polytype phase transition into the wurtzite silicon carbide polytype was observed independent on the surface polarity. The critical initial elastic deformation of the polytype phase transition into the wurtzite phase for the cubic silicon carbide polytype is larger compared to the 6H-SiC. This is due to the higher partial dislocation densities needed to transform the cubic modification into the wurtzite phase.

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Muhammad, R., Y. Wahab, Zuhairi Ibrahim, Zulkafli Othaman, S. Sakrani, and R. Ahamad. "The Effect of V/III Ratio on the Crystal Structure of Gallium Arsenide Nanowires." Advanced Materials Research 895 (February 2014): 539–46. http://dx.doi.org/10.4028/www.scientific.net/amr.895.539.

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Gallium arsenide (GaAs) nanowires were grown vertically on GaAs (111)B substrate by gold particle-assisted using metal-organic chemical vapour deposition. Transmission electron microscopy and X-Ray diffraction analysis were carried out to investigate the effects of V/III ratio and nanowire diameter on structural properties and crystallinity changes. Results show that GaAs nanowires grow preferably in the wurtzite crystal structure than zinc blende structure with increasing V/III ratio. Additionally, XRD studies have revealed that wurtzite nanowires show prominent peaks especially at (222) orientation. The optimum V/III ratio was found to be 166 with less defect structure, uniform diameter and peak prominence. The nanowires with high quality are needed in solar cells technology for energy trapping with maximum capacity.Keywords : Nanowire; crystal structure; Gallium arsenide; Vapor Liquid Solid

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Umar, Ahmad, S. H. Kim, J. H. Kim, and Y. B. Hahn. "Two-Step Growth of Hexagonal-Shaped ZnO Nanowires and Nanorods and Their Properties." Journal of Nanoscience and Nanotechnology 7, no. 12 (December 1, 2007): 4522–28. http://dx.doi.org/10.1166/jnn.2007.858.

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Single-crystalline with perfect hexagonal-shaped ZnO nanowires and nanorods, possessing the Zn-terminated (0001) facets bounded with the six-crystallographic equivalent {0110} surfaces, have been grown on Au-coated silicon substrate via thermal evaporation method using the metallic zinc powder in presence of oxygen. The detailed structural analyses reveal that the obtained nano-structures are single-crystalline with the wurtzite hexagonal phase and are preferentially oriented in the c-axis, [0001] direction. Raman spectra exhibit a sharp and strong optical phonon E2 mode at 437 cm−1 further confirms the good crystal quality with wurtzite hexagonal crystal structure for the deposited products. The room-temperature photoluminescence (PL) spectra, for both the structures, showed a sharp and strong UV emission with a suppressed green emission, indicating the good optical properties for the as-grown nanostructures.

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Koval, Olga Yu, Vladimir V. Fedorov, Alexey D. Bolshakov, Igor E. Eliseev, Sergey V. Fedina, Georgiy A. Sapunov, Stanislav A. Udovenko, et al. "XRD Evaluation of Wurtzite Phase in MBE Grown Self-Catalyzed GaP Nanowires." Nanomaterials 11, no. 4 (April 9, 2021): 960. http://dx.doi.org/10.3390/nano11040960.

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Control and analysis of the crystal phase in semiconductor nanowires are of high importance due to the new possibilities for strain and band gap engineering for advanced nanoelectronic and nanophotonic devices. In this letter, we report the growth of the self-catalyzed GaP nanowires with a high concentration of wurtzite phase by molecular beam epitaxy on Si (111) and investigate their crystallinity. Varying the growth temperature and V/III flux ratio, we obtained wurtzite polytype segments with thicknesses in the range from several tens to 500 nm, which demonstrates the high potential of the phase bandgap engineering with highly crystalline self-catalyzed phosphide nanowires. The formation of rotational twins and wurtzite polymorph in vertical nanowires was observed through complex approach based on transmission electron microscopy, powder X-ray diffraction, and reciprocal space mapping. The phase composition, volume fraction of the crystalline phases, and wurtzite GaP lattice parameters were analyzed for the nanowires detached from the substrate. It is shown that the wurtzite phase formation occurs only in the vertically-oriented nanowires during vapor-liquid-solid growth, while the wurtzite phase is absent in GaP islands parasitically grown via the vapor-solid mechanism. The proposed approach can be used for the quantitative evaluation of the mean volume fraction of polytypic phase segments in heterostructured nanowires that are highly desirable for the optimization of growth technologies.

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Imada, Saki, Toshiyuki Isshiki, Nobuyuki Tatemizo, Koji Nishio, Shuichi Mamishin, Yuya Suzuki, Katsuji Ito, et al. "Formation of various-axis-oriented wurtzite nuclei and enlargement of the a-axis-oriented region in AlFeN films deposited on Si(100) substrates." Materials Advances 2, no. 12 (2021): 4075–80. http://dx.doi.org/10.1039/d0ma01026j.

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A-axis-oriented single-crystal AlFeN grains grew from randomly oriented small wurtzite grains with deposition time on Si(100). (a) Deposition time dependence of Al K-edge XANES spectra. (b) Theoretical spectra.

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Journal articles on the topic 'Wurtzite crystal'

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