共查询到20条相似文献,搜索用时 31 毫秒
1.
Heteroepitaxial ZnO films were grown by pulsed laser deposition on various substrates such as GaN-buffered C-Al2O3, C-Al2O3, A-Al2O3, and R-Al2O3. The epitaxy nature of the films was investigated mainly by synchrotron X-ray diffraction. The results showed that the GaN interlayer plays a positive role in growing an unstrained, well-aligned epitaxial ZnO film on the basal plane of Al2O3. Importantly, the ZnO film grown on R-Al2O3 has two differently aligned domains. The dominant (1 1 0) oriented domain has much better alignment in the in-plane direction than the minor portion of (0 0 1) oriented domain, while in the out-of-plane direction the two domains have almost the same mosaic distribution. 相似文献
2.
Neyda Baguer Violeta Georgieva Lazaro Calderin Ilian T. Todorov Sake Van Gils Annemie Bogaerts 《Journal of Crystal Growth》2009,311(16):4034-4043
The nucleation and growth of titanium dioxide (TiO2) and zinc oxide (ZnO) thin films on Fe2O3 (hematite), Al2O3 (α-alumina) and SiO2 (α-quartz) are studied by molecular dynamics simulations. The results show the formation of a strong interface region between the substrate and the film in the six systems studied here. A combination of polycrystalline and amorphous phases are observed in the TiO2 films grown on the three substrates. ZnO deposition on the Fe2O3 and Al2O3 crystals yields a monocrystalline film growth. The ZnO film deposited on the SiO2 crystal exhibits less crystallinity. The simulation results are compared with experimental results available in the literature. 相似文献
3.
E. B. Sokolov B. A. Malyukov U. D. Kudakov G. A. Naida 《Crystal Research and Technology》1983,18(1):53-59
Orientation relationships of aluminium nitride on sapphire (112 6) AlN/(011 2) Al2O3 have been defined more exactly by X-ray diffractometry techniques. It has been found that, depending on the substrate misorientation from the surface plane (011 2), there can exist two kinds of azimuthal orientation of the epitaxial layer of AlN, namely, the projection of [0001] AlN on plane (011 2) Al2O3 can coincide either with [2 110] Al2O3 or with [21 1 0] Al2O3 direction. The vector field of the epitaxial layer inclination relative to the substrate misorientation has been drawn. The symmetry of this field obeys Neumann's rule. The epitaxial layer orientation has been found to depend on the sapphire substrate misorientation in direction [21 1 0]. 相似文献
4.
Ch. Georgi 《Crystal Research and Technology》1987,22(6):777-781
Epitaxial AIN grown by MOCVD on (011 2)Al2O3 substrates usually is (12 10)-oriented. Here for the first time (12 16)AIN was found in MOCVD layers. This AIN orientation is known from other growth techniques, its origin is generally not understood. An explanation is given based on twinning in the early growth stages which is also applicable to the growth of (12 16)ZnO on (011 2)Al2O3. 相似文献
5.
In an effort to design low-melting, durable, transparent glasses, two series of glasses have been prepared in the NaPO3–ZnO–Nb2O5–Al2O3 system with ZnO/Nb2O5 ratio of 2 and 1. The addition of ZnO and Nb2O5 to the sodium aluminophosphate matrix yields a linear increase of properties such as glass transition temperature, density, refractive index and elastic moduli. The chemical durability is also significantly, but nonlinearly, improved. The glass with the highest niobium concentration, 55NaPO3–20ZnO–20Nb2O5–5Al2O3 was found to have a dissolution rate of 4.5 × 10? 8 g cm? 2 min? 1, comparable to window glass. Structural models of the glasses were developed using Raman spectroscopy and nuclear magnetic resonance spectroscopy, and the models were correlated with the compositional dependence of the properties. 相似文献
6.
L.G. GossetJ.-F. Damlencourt O. RenaultD. Rouchon Ph. HolligerA. Ermolieff I. TrimailleJ.-J. Ganem F. Martin M.-N. Séméria 《Journal of Non》2002,303(1):17-23
Thin Al2O3 layers were grown by atomic layer deposition using trimethylaluminum (TMA) and water as precursors on 1.2 nm thermal SiO2 and HF cleaned Si surfaces. The stoichiometry and the contamination (H, OH and C) of as-deposited and N2 annealed thick Al2O3 layers were characterized by secondary ion mass spectrometry (SIMS), elastic recoil detection analysis (ERDA) and X-ray photoelectron spectroscopy (XPS). We show a perturbed region (≈5 nm thick) at the Al2O3/Si interface by XPS and Auger electron spectrometry (AES). Post-deposition annealings induced important interface oxidation, Si atoms injection and SiO2/Al2O3 mixture whereas the initial interface was abrupt. Silicon oxidation before Al2O3 growth highly limits interfacial oxidation and improves interfacial quality. We proposed that OH groups may play a key role to explain silicon oxidation during post-deposition annealings in inert ambience with low oxygen contamination levels. 相似文献
7.
C.-H. Kwak B.-H. Kim C.-I. Park S.-Y. Seo S.-H. Kim S.-W. Han 《Journal of Crystal Growth》2011,314(1):264-267
This study examined the structural properties of ZnO nanorods grown on Ti-buffer layers with different surface roughnesses of 1.5 and 4.0 nm. Vertically aligned ZnO nanorods were synthesized on Al2O3 substrates with a Ti-buffer layer by metal-organic chemical vapor deposition. X-ray diffraction revealed the ZnO nanorods grown on a smooth surface to have higher quality and better alignment in the ab-plane than those grown on the rough surface. Field-emission transmission electron microscopy (FE-TEM) measurements revealed a disordered layer at the ZnO/Ti interface. FE-TEM demonstrated that the Ti-buffer layer contained a mixture of ordered and amorphous phases. Energy dispersive spectroscopy (EDS) analysis revealed the Ti-buffer layers to be entirely oxides. 相似文献
8.
Th. Skoulikidis S. Polymenis A. Kostoudi 《Molecular Crystals and Liquid Crystals》2013,570(2):197-207
In previous works [Mol. Cryst. Liq. Cryst., 61, 31(1980); 95, 323 (1983)] the influence of the solid support sorptive properties on the color (reflected light band) of cholesteric liquid crystals was revealed. Qualitative and quantitative (visible diffuse reflectance spectroscopy) measurements at several temperatures on bare metal (Zn, Fe, Cu, Al) surfaces mechanically treated, on chemically and electrolytically prepared ZnO and Fe3O4, on electrolytically prepared γ1,-and γ2-Al2O3, on copper surfaces electroplated with copper and on electrolytically prepared γ2-Al2O3 under several current densities, covered with a cholesteric mixture were carried out and correlated with the sorptive properties of the support. In the present work similar optical measurements at several temperatures with the same mixture of cholesterics as the one of the previous works on nickel electrodeposits with different fiber texture were carried out, compared each other and correlated with the deduced sorptive abilities of the deposits. 相似文献
9.
J.Y. Hu H.-W. Yang Y.J. Chen J.S. Lin C.H. Lai Y.M. Lee T. Zhang 《Journal of Non》2011,357(11-13):2246-2250
This study explores a series of optical, thermal, and structural properties based on 60P2O5–30ZnO–10Al2O3 (60P) glasses that doped with varied rare earth (RE) elements Yb2O3 and P2O5 components replaced by SiO2. It was found that the glasses density decrease with SiO2 concentration added to replace P2O5, whereas they increase with increased concentration of Yb3+-doped. Moreover, the glasses transition temperature, softening temperature, and refractive index increase with Yb3+ concentrations added, whereas the thermal expansion coefficient decreases. For the 60P glasses, 7 mol% Yb2O3 doped has the maximum fluorescence which is suppressed when Yb2O3 is doped up to 9 mol%. In addition, maximum lifetime was found to be 2.68 ms at an optimal Yb3+-doping at 1 mol% for 53P2O5–7SiO2–30ZnO–10Al2O3 glass. 相似文献
10.
K. Shi A.L. Yang J. Wang H.P. Song X.Q. Xu L. Sang H.Y. Wei S.Y. Yang X.L. Liu Q.S. Zhu Z.G. Wang 《Journal of Crystal Growth》2011,314(1):39-42
Polar and non-polar ZnMgO were synthesized on different crystallographic planes (C-, R- and M-planes) of sapphire (Al2O3) substrates by metal organic chemical vapor deposition, respectively. Under the same experimental condition, polar ZnMgO nanorods were obtained on C-Al2O3 substrate whereas non-polar ZnMgO thin films were obtained on R- and M-Al2O3 substrates. The surface morphology was significantly influenced by the competition of the preferable growth directions on different sapphire substrates. On C-Al2O3 substrate, ZnMgO nanorods were vertically well-aligned with typical lengths in the range 330–360 nm. On R- and M-Al2O3 substrates, however, ZnMgO thin films with flat surfaces were obtained, whose thickness were 150 and 20 nm, respectively. Under the same condition, the C-ZnMgO deposited on C-Al2O3 substrate has the maximum growth velocity (11 nm/nim), followed by A-ZnMgO deposited on R-Al2O3 substrate (5 nm/min), and the M-ZnMgO deposited on M-Al2O3 substrate has the minimum one (0.67 nm/min). The Near-Band-Edge (NBE) emission in Photoluminescence (PL) spectra shows a clear blueshift and a slight broadening compared with that of pure ZnO samples, which suggest that the Mg content has successfully incorporated into ZnO. The different energy blueshifts (67 meV and 98 meV) of the NBE emission demonstrate that A-ZnMgO deposited on R-Al2O3 substrate has higher Mg incorporation efficiency than C-ZnMgO on C-Al2O3 substrate. 相似文献
11.
Takahiro Hamada Akihiro Ito Eiji Fujii Dewei Chu Kazumi Kato Yoshitake Masuda 《Journal of Crystal Growth》2009,311(14):3687-3691
High-quality zinc oxide (ZnO) films were successfully grown on ZnO-buffered a-plane sapphire (Al2O3 (1 1 2¯ 0)) substrates by controlling temperature for lateral growth using chemical bath deposition (CBD) at a low temperature of 60 °C. X-ray diffraction analysis and transmission electron microscopy micrographs showed that the ZnO films had a single-crystalline wurtzite structure with c-axis orientation. Rocking curves (ω-scans) of the (0 0 0 2) reflections showed a narrow peak with full width at half maximum value of 0.50° for the ZnO film. A reciprocal space map indicated that the lattice parameters of the ZnO film (a=0.3250 nm and c=0.5207 nm) were very close to those of the wurtzite-type ZnO. The ZnO film on the ZnO-buffered Al2O3 (1 1 2¯ 0) substrate exhibited n-type conduction, with a carrier concentration of 1.9×1019 cm−3 and high carrier mobility of 22.6 cm2 V−1 s−1. 相似文献
12.
Hirokazu Masai Toshiro Tanimoto Takumi Fujiwara Syuji Matsumoto Yoshihiro Takahashi Yomei Tokuda Toshinobu Yoko 《Journal of Non》2012,358(2):265-269
The authors investigate the structural change of a ZnO–P2O5 sintered matrix for the preparation of SnO-doped zinc phosphate (SZP) glass using a platinum crucible. Heat treatment of zinc oxide and ammonium phosphate at 800 °C causes the formation of a Zn2P2O7-like species, which is effective in preventing damage to the platinum crucible. Although the thermal property of the glass was affected by added Al2O3, Al2O3 hardly affects the quantum efficiency of the SZP glass phosphor. This process is important for the fabrication of contamination-free phosphate glass using ammonium phosphate as a starting material. 相似文献
13.
The leaching of some binary and ternary lithium silicate glasses and their respective glass-ceramics by HCl is reported.The leaching rate of lithium silicate glasses gradually decreases with the decrease of the percentage of Li2O or by the introduction of small amounts of a third component, e.g. Al2O3, MgO, ZnO or B2O3. With a further increase in the proportions of B2O3 or ZnO the rate of leaching increases. The rate of leaching is also substantially modified by the conversion of glasses into glasses-ceramics.The results obtained are discussed in terms of the effects of the different ions on the rate of the interdifussion of the lithium and hydrogen ions in the glass and the leached layer, the phase separation developed in the glass, the type and concentration of crystalline phases developed in glass-ceramics and the composition of the residual glass phase. 相似文献
14.
T. Roch E. Dobročka M. Mikula A. Pidík P. Durina A.A. Haidry T. Plecenik M. Truchlý B. Grancic A. Plecenik P. Kúš 《Journal of Crystal Growth》2012,338(1):118-124
Many applications based on TiO2 thin films are strongly influenced by the film crystalline quality, microstructure and surface morphology. We have utilized x-ray scattering methods for crystal structure study of TiO2 films, grown by DC reactive magnetron sputtering without heating. We have observed the formation of ordered phases after post-deposition ex-situ annealing in air at 600 °C. The distinct biaxial texture with respect to the c-plane (0001) Al2O3 substrate surface, which developed during heating, shows remarkable patterns in pole figures. We have identified epitaxial relationships of anatase A(001)[110]6sub(001)[11?00] and rutile R(100)[001]6sub(0001)[100] within single TiO2 layer. In addition, within the same sample, we have observed the anatase in (112) orientation with two in-plane relationship options A(112)[11?0]6sub(0001)[21?1?0] and A(112)[11?0]6sub(0001)[11?00]. 相似文献
15.
William E. Fenwick Nola Li Tianming Xu Andrew Melton Shenjie Wang Hongbo Yu Christopher Summers Muhammad Jamil Ian T. Ferguson 《Journal of Crystal Growth》2009,311(18):4306-4310
GaN thin films have been grown on Si(1 1 1) substrates using an atomic layer deposition (ALD)-grown Al2O3 interlayer. This thin Al2O3 layer reduces strain in the subsequent GaN layer, leading to lower defect densities and improved material quality compared to GaN thin films grown by the same process on bare Si. XRD ω-scans showed a full width at half maximum (FWHM) of 549 arcsec for GaN grown on bare Si and a FWHM as low as 378 arcsec for GaN grown on Si using the ALD-grown Al2O3 interlayer. Raman spectroscopy was used to study the strain in these films in more detail, with the shift of the E2(high) mode showing a clear dependence of strain on Al2O3 interlayer thickness. This dependence of strain on Al2O3 thickness was also observed via the redshift of the near bandedge emission in room temperature photoluminescence (RT-PL) spectroscopy. The reduction in strain results in a significant reduction in both crack density and screw dislocation density compared to similar films grown on bare Si. Screw dislocation density of the films grown on Al2O3/Si substrates approaches that of typical GaN layers on sapphire. This work shows great promise for the use of oxide interlayers for growth of GaN-based LEDs on Si. 相似文献
16.
17.
《Journal of Crystal Growth》2003,247(3-4):393-400
Using a highly conductive ZnO(ZnAl2O4) ceramic target, c-axis-oriented transparent conductive ZnO:Al2O3 (ZAO) thin films were prepared on glass sheet substrates by direct current planar magnetron sputtering. The structural, electrical and optical properties of the films (deposited at different temperatures and annealed at 400°C in vacuum) were characterized with several techniques. The experimental results show that the electrical resistivity of films deposited at 320°C is 2.67×10−4 Ω cm and can be further reduced to as low as 1.5×10−4 Ω cm by annealing at 400°C for 2 h in a vacuum pressure of 10−5 Torr. ZAO thin films deposited at room temperature have flaky crystallites with an average grain size of ∼100 nm; however those deposited at 320°C have tetrahedron grains with an average grain size of ∼150 nm. By increasing the deposition temperature or the post-deposition vacuum annealing, the carrier concentration of ZAO thin films increases, and the absorption edge in the transmission spectra shifts toward the shorter wavelength side (blue shift). 相似文献
18.
Kurlov V. N. Mileiko S. T. Kolchin A. A. Starostin M. Yu. Kiiko V. M. 《Crystallography Reports》2002,47(1):S53-S62
A new approach is developed for growing relatively inexpensive single-crystal and eutectic oxide fibers suitable for the fabrication of high-temperature composite materials. Sapphire (Al2O3), YAG (Y3Al5O12), mullite (3Al2O3 · 2SiO2), YAP (YAlO3), and eutectic (Al2O3-Y3Al5O12, Al2O3-ZrO2 (Y2O3), and Al2O3-Gd2O3) fibers are produced by the internal crystallization method, and their mechanical strength and micro-structures are studied. 相似文献
19.
The effect of Al2O3 on viscosity in the calcium silicate melt-based system containing Na2O and CaF2 was investigated and correlated with the melt structure using FTIR (Fourier transform infrared) spectroscopy, XPS (X-ray photoelectron spectroscopy), and Raman spectroscopy. Substituting SiO2 with Al2O3 modified the dominant silicate network into a highly structured alumino-silicate structure with the aluminate structure being particularly prevalent at 20 mass% of Al2O3 and higher. As the melts become increasingly polymerized with higher Al2O3 content, the fraction of symmetric Al–O0 stretching vibrations significantly increased and the viscosity increased. XPS showed a decrease in the amount of non-bridged oxygen (O?) but an increase in bridged oxygen (O0) and free oxygen (O2?) with higher Al2O3. Although changes in the structure and viscosity with higher CaO/(SiO2 + Al2O3) were not significant, the symmetric Al–O0 stretching in the [AlO4]5?-tetrahedral units decreased. The apparent activation energy for viscous flow varied from 118 to 190 kJ/mol. 相似文献
20.
A series of Bi2O3–BaO–SiO2–RxOy (designated BiBaSi glass) glass sealants doped with different contents of α-Al2O3 have been investigated. Al2O3 was added as a modifier to affect the structure and the behavior of the glass. The thermal properties such as glass transition temperature (Tg), softening temperature (Tf) and coefficient of thermal expansion (CTE) were measured by a dilatometer. The sealing performance was investigated by sealing a SOFC single cell stack and measuring its open circuit voltage (OCV). Tg, Tf and suitable usage temperature of the sealants increased with increasing Al2O3 content in the glass, while CTE decreased. When the Al2O3 content was lower than 10 wt.%, excellent sealing performance was observed. 相似文献