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X-ray Rocking Curve (x-ray + rocking_curve)
Selected AbstractsBragg,(Bragg)m,Laue diffraction and its interference fringePHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2009Kenji Hirano Abstract X-Ray rocking curves from side surface of a thin plane-parallel Ge crystal are measured under the condition where the dispersion of the refracted angle is quite large. In the diffracted beams from side surface are observed, which are analysed by using Wagner's approach for Bragg,(Bragg)m,Laue case. The origin of the fringes is explained by the interference between diffraction beams in Bragg,Laue case and that in Bragg,Bragg,Laue case. [source] Growth, etching morphology and spectra of LiAlO2 crystalCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2008Taohua Huang Abstract ,-LiAlO2 single crystal was successfully grown by Czochralski method. The crystal quality was characterized by X-ray rocking curve and chemical etching. The effects of air-annealing and vapor transport equilibration (VTE) on the crystal quality, etch pits and absorption spectra of LiAlO2 were also investigated in detail. The results show that the as-grown crystal has very high quality with the full width at half maximum (FWHM) of 17.7-22.6 arcsec. Dislocation density in the middle part of the crystal is as low as about 3.0×103 cm,2. The VTE-treated slice has larger FWHM value, etch pits density and absorption coefficient as compared with those of untreated and air-annealed slices, which indicates that the crystal quality became inferior after VTE treatment. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Structural evaluation of GaN/sapphire grown by epitaxial lateral overgrowth by X-ray microdiffractionPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 7 2006M. Drakopoulos The cover picture from the article [1] depicts the geometry of X-ray diffraction on a GaN/sapphire structure made by a two-step epitaxial lateral overgrowth (2S-ELO) process. Below, the X-ray rocking curve as a function of the vertical beam position in 2S-ELO GaN/sapphire is shown. A low intensity line diverging from the main peak position (arrow) may be interpreted as the disappearance of a winged crystal region due to dislocation curvature. This paper is a presentation from the 6th International Conference on Nitride Semiconductors held in Bremen, Germany, in 2005. Further articles from ICNS-6 are also being published in phys. stat. sol. (a) 203, No. 7 (2006) and phys. stat. sol. (c) 3, No. 6 (2006). [source] Unintentionally doped InN grown onto an atomically flat AlN intermediate layer using plasma-assisted molecular beam epitaxyPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 7 2006K. R. Wang Abstract Unintentionally doped InN has been grown onto an atomically flat AlN intermediate layer on top of the Si(111) substrate using plasma-assisted molecular beam epitaxy (PA-MBE). Though there are lots of micrometer-size indium droplets randomly distributed on the top of the surface, the highest electron mobility of this InN thin film measured at room temperature by van der Pauw method is still higher than 1000 cm2/V s with a carrier concentration of 5,8.9 × 1018 cm,3. A symmetrical X-ray rocking curve is measured and the full-width-at-half-maximum (FWHM) of this sample is 1089 arcsec. In the meantime, the threading dislocation (TD) density of this material is estimated to around 9.8 × 108 cm,2 , 7.5 × 109 cm,2 depending on the probing regions that are studied by the etching technique and field-emission scanning electron microscopy (FE-SEM). (2 × 1) in situ reflection high-energy electron diffraction (RHEED) patterns show that this sample is grown under In-rich environment with possible In-terminated surface. From the FE-SEM pictures which were taken from the samples after 10 minutes etching in hydrochloride, the surface morphology shows In-polarity-like patterns that coincide with those procured in RHEED. To select and grow a high-quality laminated AlN as intermediate layer is believed to be the major step in obtaining this high electron mobility InN thin film on Si substrate. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Impact of nitridation on structural and optical properties of MOVPE-grown m-plane GaN layers on LiAlO2PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009C. Mauder Abstract In this paper, we investigate the influence of the nitridation of LiAlO2 substrates on the growth of m-plane (1-100) GaN layers by metal-organic vapour phase epitaxy (MOVPE). Before thin film deposition, we performed an in-situ substrate pretreatment by exposing the wafer to NH3 for different times between no pretreatment and 300 s. The properties of subsequently grown layers show a significant dependency on this nitridation step. We find that this procedure is essential for obtaining pure m-plane GaN films and has a beneficial effect on the X-ray rocking curve (XRC) full width at half maximum (FWHM) value, which decreases by almost two orders of magnitude. Deposited layers with NH3 pretreatment also exhibit much smoother surfaces with a reduction of the root mean square (RMS) roughness value from ,20 to ,6 nm. Additionally, the nitridation greatly increases the GaN band edge emission intensity in room temperature (RT) photoluminescence (PL) spectroscopy. Furthermore, we compare the sensitivity of the substrate against water for uncoated LiAlO2 wafers with and without nitridation process. While the untreated surface shows a clear roughening when dipped into de-ionized (DI) water for 5 min, we can see no significant impact on the nitridated substrate surface. This indicates a change in surface composition which protects the sensitive substrate surface and provides good conditions for the nucleation of high-quality m-plane GaN films. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Atmospheric-pressure MOVPE growth of In-rich InAlNPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008Y. Houchin Abstract This paper reports the atmospheric-pressure MOVPE growth of In-rich InAlN. All InAlN films prepared here (Al content:0, 0.43) do not show phase separation. The incorporation of Al in InAlN is decreased with increasing growth temperature. A decrease in Al content is also observed for films grown at a position farther from the up-stream end of the susceptor. The marked decrease in the Al content along the gas flow direction seems to be caused by the shortage of TMA supply at the downstream by the parasitic reaction of TMA. A single-crystalline InAlN film with an Al content of 0-0.43 is successfully grown by adjusting growth temperature and TMA/(TMI+TMA) molar ratio. FWHM of X-ray rocking curve for InAlN is increased with increasing Al content. The carrier concentrations in InAlN films are comparable to that in InN (1-5 × 1019 cm,3). All the single-crystalline InAlN films with an Al content of 0-0.3 show a photoluminescence at room temperature. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth of high-quality 1-inch diameter AlN single crystal by sublimation methodPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007N. Mizuhara Abstract 1-inch diameter AlN single crystals with the thickness of 0.025,2 mm were grown on SiC substrates by the sublimation method. Crystalline qualities were evaluated by X-ray diffraction and EPD measurements. The FWHM of X-ray rocking curve for (0002) reflection was 281 arcsec with 1.2-mm thick crystal and dislocation density measured by EPD was 1.6×106/cm2 with 0.8-mm thick crystal. These results were well consistent with the dependence of those properties on the thickness of the crystal, which was found in our previous work on 10-mm diameter crystals. According to this dependence, growing the thick AlN crystal on SiC substrates by the sublimation method is expected to lead to high-quality free-standing 1-inch AlN substrates. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] High temperature growth of AlN film by LP-HVPEPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007K. Tsujisawa Abstract AlN films were grown on AlN/sapphire templates at 1400,1500 °C using low-pressure hydride vapor phase epitaxy (LP-HVPE). Compared to the step-flow growth of AlN film at 1200 °C with growth rate of 2.1 ,m/h, AlN films with atomic steps were obtained at 1400,1500 °C even with high growth rate. For the AlN film grown at 1450 °C with growth rate of 14.3 ,m/h, the RMS value is 0.75 nm and the FWHM values of (0002) and (10-12) X-ray rocking curve (XRC) are 351 and 781 arcsec, respectively. Since the FWHM value of (10-12) XRC for the AlN/sapphire template is 1492 arcsec, the crystal quality of HVPE-grown AlN is greatly improved compared with the AlN/sapphire template, which is also confirmed by TEM observation. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Crystallographic deterioration of MOVPE InN during the growthPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007K. Sugita Abstract This paper reports the crystallographic degradation of MOVPE InN during the growth. Using FWHMs of X-ray rocking curve, tilt ((0002)) and twist ((10-10)) angle distributions are evaluated and effects of the major growth parameters, such as growth temperature, growth time and with/without GaN buffer in the degradation, are revealed. With increasing either thickness of grown InN or growth temperature up to 600 °C, the tilt angle distribution is markedly increased, indicating the crystallographic degradation of grown films. The use of a GaN buffer reduces such degradation. Since the twist angle distribution is scarcely changed by such growth parameters, the destruction of InN crystals during growth and annealing is concluded to be anisotropic. The trends of the crystallographic degradation revealed here are in good agreement with those for the electrical and optical degradation previously reported. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effects of V/III flux ratio on AlInGaN/AlGaN quantum wells grown by atmospheric pressure MOCVDPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2005R. J. Choi Abstract We investigated the structural and optical properties of AlInGaN/AlGaN quantum wells (QWs) and the quaternary AlInGaN epilayers as a function of V/III flux ratio (flow rate of NH3). From the photoluminescence and cathodoluminescence (CL) measurements, the emission wavelengths of the AlInGaN/AlGaN QWs linearly became blueshifted and the intensities decreased with increasing the flow rate of NH3. In the X-ray rocking curve, a pattern of the sample grown at lower NH3 flow rate gives an indication of the good crystalline quality of the films. The monochromated scanning CL image of the AlInGaN epilayers measured at around 80 K showed that more densely and uniformly distributed bright spot densities, indicating In segregation regions, increased at lower NH3 flow rate. Therefore, these results suggest that the relatively decrease of NH3 flow rate results in the increase of In composition fluctuations into the AlInGaN alloys, which generate exciton localized states, and thereby enhances the emission. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] HVPE Growth of GaN on a GaN Templated (111) Si SubstratePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2003Y. Honda Abstract The hydride vapor phase epitaxial (HVPE) growth of GaN was attempted on a (111) Si substrate. In order to suppress the chemical reaction of the Si at high temperatures, the surface of the substrate was covered by a thin SiO2 film or GaN pyramids which were grown by selective metalorganic vapor phase epitaxy (MOVPE). The GaN pyramids served as the seeds for the following HVPE growth of GaN. Uniform layer of 12 ,m thick wurtzite GaN was achieved successfully. The full width at half maximum (FWHM) of (0004) X-ray rocking curve was 450 arcsec. The cathode luminescence (CL) spectra at 4.2 K exhibited a strong band edge emission peak of which FWHM was as broad as 30.3 meV. [source] Epitaxial Growth of AlN Layers on SiC Substrates in a Hot-Wall MOCVD SystemPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2003A. Kakanakova-Georgieva Abstract In this study we report the successful growth of AlN and AlN/GaN on SiC substrates in a MOCVD process based on a hot-wall susceptor design. Different features of AlN growth are established depending on the total reactor pressure, temperature, off-cut SiC substrate orientation and V-to-III gas-flow ratio. The feasibility of the hot-wall MOCVD concept is demonstrated by the performance of AlN/GaN structures with state-of-the-art properties with strong potential for further optimization. A narrower X-ray rocking curve over the asymmetric 10.4 than the symmetric 00.2 reflection clearly underlines the high overall crystal quality of the GaN layers on AlN buffers grown in this type of MOCVD reactor. [source] Growth and characterization of near stoichiometric LiNbO3 single crystalCRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2007S. H. Yao Abstract A near stoichiometric LiNbO3 single crystal has been grown by the Czochralski method from a 58.5% Li melt hold in a large platinum crucible. High resolution X-ray rocking curves of 300 and 0006 reflections indicated that the near stoichiometric LiNbO3 crystal possesses the high structural quality. Compared with the congruent LiNbO3, the near stoichiometric LiNbO3 possesses shorter ultraviolet absorption edge, thus higher Li concentration. The OH, infrared absorption band analyses showed that the Li concentration in the near stoichiometric LiNbO3 crystal is higher than that in the congruent LiNbO3 crystal. This result is in good agreement with that of the ultraviolet absorption edge. The electro-optic (EO) coefficient ,22 of the near stoichiometric LiNbO3 crystal was measured to be 6.75 pm/V higher than that of congruent LiNbO3 crystal. It also proves the near stoichiometric LiNbO3 electro-optic Q-switched requires a low driving voltage and it is advantageous for the device performance. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Low-temperature growth of high quality AlN films on carbon face 6H-SiCPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 1 2008Myunghee Kim Abstract AlN films have been grown on atomically flat carbon face 6H-SiC (000) substrates by pulsed laser deposition and their structural properties have been investigated. In-situ reflection high-energy electron diffraction observations have revealed that growth of AlN at 710 °C proceeds in a Stranski,Krastanov mode, while typical layer-by-layer growth occurs at room temperature (RT) with atomically flat surfaces. It has been revealed that the crystalline quality of the AlN film is dramatically improved by the reduction in growth temperature down to RT and the full width at half maximum values in the X-ray rocking curves for 0004 and 102 diffractions of the RT-grown AlN film are 0.05° and 0.07°, respectively. X-ray reciprocal space mapping has revealed that the introduction of misfit dislocations is suppressed in the case of RT growth, which is probably responsible for the improvement in crystalline quality. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] InxGa1,xAs single crystal growth by dispersing local misfit stressPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2006Hiroaki Miyata Abstract We succeeded in growing a single crystal by dispersing the misfit stress around an initial solid-liquid interface in In0.3Ga0.7As ternary bulk crystal growth. We gradually increased concentration of indium arsenide so that the local misfit stress could be smaller than critical resolved shear stress. The traveling lqiuidus-zone (TLZ) method was applied for growing crystals. To grow a single In0.3Ga0.7As crystal, an In0.1Ga0.9As single crystal region was grown first on a GaAs seed. Then the concentration of indium arsenide was gradually increased up to In0.3Ga0.7As by lowering temperature at the interface. As a result, In0.3Ga0.7As single crystals of 2 mm in thickness, 10 mm in width and more than 25 mm in length were successfully obtained. Mean value of full width half maximum (FWHM) of X-ray rocking curves in the In0.3Ga0.7As grown crystal was 0.116°. It is not small enough but it will be improved by increasing compositional homogeneity. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Three-beam X-ray rocking curves calculated from computer-simulated pinhole topographsACTA CRYSTALLOGRAPHICA SECTION A, Issue 4 2010Gen Ishiwata X-ray rocking curves are reported which have been obtained by fast-Fourier-transforming X-ray amplitudes in three-beam pinhole topographs. The topographs were computer-simulated based on the Takagi,Taupin equation with the condition of spherical-wave X-ray incidence. This is another strategy for calculating three-beam rocking curves, which are usually calculated based on the Ewald,Laue dynamical theory. [source] Fabrication of thick AlN film by low pressure hydride vapor phase epitaxyPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006Yu-Huai Liu Abstract Thick AlN crystals were grown by conventional hydride vapor phase epitaxy (HVPE) on AlN/sapphire templates under low pressure (,15 Torr) at high temperature (1100 °C,1200 °C). Colorless, mirror-like AlN films were obtained at the growth rates of up to 20.6 ,m/h. The best root mean square (RMS) value of atomic force microscope (AFM) observations for the AlN surface was 0.19 nm in a surface of 5×5 ,m2. The typical values of full width half maximum (FWHM) of X-ray rocking curves for (0002) and (102) diffraction of AlN films were 173,314 arcsec and 1574,1905 arcsec, respectively. We also investigated the influences of carrier gas, growth temperature and growth rate on the crystal quality. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Improved crystallinity and polarity manipulation of MOVPE-grown GaN epilayers with deep sapphire-nitridation followed by Al-preflow at high temperaturesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003B. W. Seo Abstract The polarity manipulation and crystallinity of GaN epilayers grown by metalorganic vapor phase epitaxy (MOVPE) on deeply nitrided c -sapphire was studied by using TMAl preflow at high temperatures (HT-TMAl preflow) of 1100 °C. It was found that the HT-TMAl preflow was very effective to change the surface polarity; the successful change to Ga-polarity from N-polarity and the atomic-steps were observed when the Al layer thickness was above two-monolayers, though it was remained N-polarity without the Al layer. The crystallinity of GaN epilayer is increased using HT-TMAl preflow. High quality Ga-polarity GaN epilayers was grown by this technique and typical full width at half maximums (FWHMs) for X-ray rocking curves were 300,320 arcsec and 450,480 arcsec for (002) and (102) diffractions, respectively. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Measurement of X-ray rocking curves in the Bragg,Laue caseACTA CRYSTALLOGRAPHICA SECTION A, Issue 5 2008Masami Yoshizawa X-ray rocking curves in the Bragg,Laue case diffracting from the side surface of a plane-parallel crystal have been measured using a high-resolution optical system. The full width at half-maximum of the rocking curves is approximately three times narrower than that measured from the top surface. The characteristics of the transmitted beam from the side surface are almost the same as those through a thin crystal in the Bragg case. The rocking curves and the direction of X-ray energy flow in the crystal observed in the experiment can be reproduced using Wagner's approach [Wagner (1956), Z. Phys.146, 127,168]. [source] Absolute measurement of lattice parameter in single crystals and epitaxic layers on a double-crystal X-ray diffractometerACTA CRYSTALLOGRAPHICA SECTION A, Issue 3 2005M. Fatemi Details of the recently developed `zone technique' for the absolute measurement of lattice parameter and strain in single-crystal solids and thin films are presented. The method is based on measuring X-ray rocking curves from a few equatorial planes within a suitable zone and correcting their peak positions at once with a single zero offset. In contrast to the comparative method, which usually requires use of two opposite azimuthal directions, those in the zone technique can often be completed in only one azimuthal setting. A typical strained layer in the cubic system can be fully and rapidly characterized with only three rocking curves. The technique is suitable for routine applications under typical laboratory conditions, and for high-precision measurements of nearly perfect crystals in a controlled environment, with a potential parts in 10,million accuracy. This degree of accuracy is a direct consequence of the zero offset correction procedure, which effectively cancels a large portion of the misalignment errors in the diffractometer. The use of the (n,,n) geometry substantially reduces the errors of eccentricity compared to the Bond technique, and its stronger reflections enable the measurement of small samples about 0.05,mm in length with relative ease. The technique is illustrated with examples, and its extension to the triple-axis (,,2,) instruments is discussed. [source] A lamellar model for the X-ray rocking curves of sagittally bent Laue crystalsACTA CRYSTALLOGRAPHICA SECTION A, Issue 1 2003Z. Zhong The use of sagittally bent asymmetric Laue crystals in horizontally focusing monochromators for high-energy synchrotron X-rays necessitates simulation of the X-ray reflectivity by such crystals. Based on the theory of the lattice distortion in the diffraction plane of sagittally bent Laue crystals, a lamellar model was developed to predict their rocking curves. The model was experimentally verified by rocking-curve measurements from various reflections on silicon crystals of four representative orientations, sagittally bent to various radii, using X-rays of 67,keV energy. [source] Growth and characterisation of Zn:LiNbO3/Mg:LiNbO3 multilayer thin films grown by liquid phase epitaxyCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2006H. J. Lee Abstract 1, 3 and 5 mol% ZnO doped LiNbO3 film and 2 mol% MgO doped LiNbO3 multilayer films were grown on the LiNbO3 (001) substrate by liquid phase epitaxy (LPE) method with a Li2O-V2O5 system. We examined the optical transmission spectra of the Zn:LiNbO3 by Fourier Transform-Infrared Spectrophotometer (FT-IR). The crystallinity and the lattice mismatch between the Zn:LiNbO3 film and Mg:LiNbO3 film was confirmed by x-ray rocking curve (XRC) and observed the ZnO and MgO distribution in the cross-section of the multilayer thin films by electron probe micro analyzer (EPMA). Furthermore, the surface morphology of the films was observed using atomic force microscopy (AFM). (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||