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High Growth Temperature (high + growth_temperature)
Selected AbstractsIncreased Interface Strength in Carbon Fiber Composites through a ZnO Nanowire InterphaseADVANCED FUNCTIONAL MATERIALS, Issue 16 2009Yirong Lin Abstract One of the most important factors in the design of a fiber reinforced composite is the quality of the fiber/matrix interface. Recently carbon nanotubes and silicon carbide whiskers have been used to enhance the interfacial properties of composites; however, the high growth temperature degrade the fiber strength and significantly reduce the composite's in-plane properties. Here, a novel method for enhancing the fiber/matrix interfacial strength that does not degrade the mechanical properties of the fiber is demonstrated. The composite is fabricated using low-temperature solution-based growth of ZnO nanowires on the surface of the reinforcing fiber. Experimental testing shows the growth does not adversely affect fiber strength, interfacial shear strength can be significantly increased by 113%, and the lamina shear strength and modulus can be increased by 37.8% and 38.8%, respectively. This novel interface could also provide embedded functionality through the piezoelectric and semiconductive properties of ZnO. [source] Atomic layer epitaxy of GaMnAs on GaAs(001)PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2007M. Ozeki Abstract A self-limiting mechanism in atomic layer epitaxy (ALE) has been investigated for the heterogrowth of GaMnAs on GaAs(001) substrate. In the ALE, trimethylgallium, bismethylcyclopentadienylmanganese and trisdimethylaminoarsine were used as source materials of gallium, manganese and arsenic atoms, respectively. Although the growth of GaMnAs was carried out at a high growth temperature of 500 °C, a distinct self-limiting mechanism was observed for the manganese alloy composition up to 6% and the epitaxial layer had no indications of including MnAs phase. The layer showed an atomically flat surface morphology reflecting the self-limiting growth. The self-limiting mechanism was largely affected by the lattice mismatch between GaMnAs epitaxial layer and GaAs substrate. When the manganese alloy composition exceeded 7%, the self-limiting mechanism was broken and MnAs precipitates were observed in the epitaxial layer. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effects of Mg fluctuation on the electrical and optical properties in p-GaN/undoped GaN layers dependent on the growth temperaturePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003C. S. Kim Abstract The effects of heavly Mg doping dependent on the growth temperature of p-GaN layers grown on undoped GaN layers by metalorganic chemical vapor deposition (MOCVD) on electrical and optical properties were studied by capacitance,voltage (C,V) and temperature-dependent photoluminescence (TDPL), respectively. At high growth temperature of p-GaN above 1110 °C, optical microscopy images as well as atomic force microscopy (AFM) images show polygonal hillocks on heavily Mg-doped GaN surface. It was also found that fluctuation of Mg concentration ([Mg]) measured by secondary ion mass spectroscopy (SIMS) was increased with increasing growth temperature. These phenomena were appeared to decrease NA,ND and change PL emission from 3.1,3.2 eV of conduction band-to-shallow Mg acceptor (e, A) transition to 2.8,2.9 eV of Mg-related deep donor-to-acceptor pair (DAP) transition. [source] Effect of growth interruption on In-rich InGaN/GaN single quantum well structuresPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003Soon-Yong Kwon Abstract We successfully grew In-rich InGaN/GaN single quantum well structures by metal-organic chemical vapor deposition and confirmed their formation by optical and structural measurements. Relatively high growth temperature (730 °C) for InGaN layer facilitated the formation of 2-dimensional quantum well structures, presumably due to high adatom mobility. As the growth interruption time increased, the PL emission efficiency from InGaN layer improved with peak position blue-shifted and the dislocation density decreased by one order of magnitude. The high resolution cross-sectional TEM images clearly showed that the In-rich InGaN layer thickness reduced from 2.5 nm (without GI) to about 1 nm (with 10 s GI) and the InGaN/GaN interface became very flat with 10 s GI. We suggest that decomposition and mass transport processes on InGaN during GI is responsible for these phenomena. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Repeated Growing and Annealing Towards ZnO Film by Metal-Organic CVD,CHEMICAL VAPOR DEPOSITION, Issue 7-9 2009Chia-Cheng Wu Abstract ZnO deposited on sapphire substrate is investigated as a function of growth temperature in the range 350,650,°C. The surface morphology of ZnO structures changes significantly with increasing growth temperature. Though ZnO crystal quality and optical property can be improved under high growth temperature, ZnO is inclined to form nanostructures. Therefore, we propose the repeated growing and annealing (RGA) growth mode as a reliable and reproducible way for the growth of ZnO film. The RGA growth mode is performed at a growth temperature of 450,°C for 8,min, an anneal temperature of 650,°C for 20,min, and repeatedly switched between growing and annealing. Meanwhile, we compare the effects of annealing under Ar, N2, and O2, and found that a low resistivity of 3.4,×,10,3,, cm and a high mobility of 85.2,cm2 V,1 s,1 can be obtained annealing under N2. [source] Low-cost growth of AlN using vectored-flow epitaxy for the purpose of water sterilisation in a rural environmentPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2008Matthew Branch Abstract The high V/III ratio required for the Metalorganic Chemical Vapour Deposition (MOCVD) growth of AlN using the precursors trimethylaluminium and ammonia have contributed to the excessive costs of producing ultra violet light emitting diodes (UVLEDs) which can be used in water purification. This paper introduces a novel growth technique, vectored-flow epitaxy (VFE), which maintains the separation between gaseous reagents within the growth chamber. In addition, the VFE technique, which employs atmospheric pressure growth, also pre cracks the ammonia prior to injection and thereby significantly reduces the high V/III ratio required for the growth of this material. The pre cracked ammonia also removes the need for high growth temperatures, which is known to be necessary for its thermal decomposition. With this technique, 2 ,m/h growth is possible at a V/III ratio of 50. These advances will contribute to the development of a cost-effective solution to the treatment of drinking water in a rural environment. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Rubisco expression in rice leaves is related to genotypic variation of photosynthesis under elevated growth CO2 and temperaturePLANT CELL & ENVIRONMENT, Issue 12 2003R. W. GESCH ABSTRACT Genetic modifications of agronomic crops will likely be necessary to cope with global climate change. This study tested the hypotheses that genotypic differences in rice (Oryza sativa L.) leaf photosynthesis at elevated [CO2] and temperature are related to protein and gene expression of Rubisco, and that high growth temperatures under elevated [CO2] negatively affect photosystem II (PSII) photochemical efficiency. Two rice cultivars representing an indica (cv. IR72) and japonica type (cv. M103) were grown in 350 (ambient) and 700 (elevated) µmol CO2 mol,1 at 28/18, 34/24 and 40/30 °C sinusoidal maximum/minimum, day/night temperatures in outdoor, sunlit, environment-controlled chambers. Leaf photosynthesis of IR72 favoured higher growth temperatures more than M103. Rubisco total activity and protein content were negatively affected in both genotypes by high temperatures and elevated CO2. However, at moderate to high growth temperatures, IR72 leaves averaged 71 and 39% more rbcS transcripts than M103 under ambient and elevated CO2, respectively, and likewise had greater Rubisco activity and protein content. Expression of psbA (D1 protein of PSII) in IR72 leaves increased with temperature, whereas it remained constant for M103, except for a 20% decline at 40/30 °C under elevated CO2. Even at the highest growth temperatures, PSII photochemical efficiency was not impaired in either genotype grown under either ambient or elevated CO2. Genotypic differences exist in rice for carboxylation responses to elevated CO2 and high temperatures, which may be useful in developing genotypes suited to cope with global climate changes. [source] | |||||||||||||