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Study of depth-dependent tetragonal distortion of quaternary AIInGaN epilayer by Rutherford backscattering/channeling 下载免费PDF全文
<正>A 240-nm thick Al0.4In0.02Ga0.58N layer is grown by metal organic chemical vapour deposition,with an over 1-μm thick GaN layer used as a buffer layer on a substrate of sapphire(0001).Rutherford backscattering and channeling are used to characterize the microstructure of AlInGaN.The results show a good crystalline quality of AlInGaN(xmin= 1.5%) with GaN buffer layer.The channeling angular scan around an off-normal(1213) axis in the {1010} plane of the AlInGaN layer is used to determine tetragonal distortion eT,which is caused by the elastic strain in the AlInGaN.The resulting AlInGaN is subjected to an elastic strain at interfacial layer,and the strain decreases gradually towards the near-surface layer.It is expected that an epitaxial AlInGaN thin film with a thickness of 850 nm will be fully relaxed (eT=0). 相似文献
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To study ion beam induced modifications into MOCVD grown wurtzite AlInN layers, neon ions were implanted on the samples with four doses ranging from 1014 to 9×1015 ions/cm2. Structural characterization was carried out by X-ray diffraction and Rutherford backscattering spectroscopy (RBS) techniques. XRD analysis revealed that GaN related peak for all samples remains at its usual Bragg position of 2θ=34.56° whereas a shift in AlInN peak takes place from its position of 2θ=35.51° for as-grown sample. Rutherford back scattering (RBS) analysis indicated that peak related to Ga atoms in capping layer provided evidence of partial sputtering of GaN cap layers. Moreover, Al peak position is shifted towards lower channel side and width of the signal is increased after implantation, which pointed to the inwards migration of Al atoms away from the AlInN surface. The results suggested that partial sputtering of cap layer has taken place without uncovering the underneath AlInN layer. 相似文献
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Characterization of n-GaN dilute magnetic semiconductors by cobalt ions implantation at high-fluence
G. Husnain Yao Shu-DeIshaq Ahmad H.M. RafiqueArshad Mahmood 《Journal of magnetism and magnetic materials》2012,324(5):797-801
In this study, we present the structural and magnetic characteristics of cobalt ions implantation at a high-fluence (5×1016 cm−2) into n-GaN epilayer of thickness about 1.6 μm. The n-GaN was grown on sapphire by metal organic chemical vapor deposition (MOCVD). Rutherford backscattering channeling was used for the structural study. After implantation, samples were annealed at 700, 800 and 900 °C by rapid thermal annealing in ambient N2. XRD measurements did not show any secondary phase or metal related-peaks. High resolution X-ray diffraction (HRXRD) was performed as well to characterize structures. Well-defined hysteresis loops were observed at 5 K and room temperature using alternating gradient magnetometer AGM and Superconducting Quantum Interference Device (SQUID) magnetometer. Temperature-dependent magnetization indicated magnetic moment at the lowest temperatures and retained magnetization up to 380 K for cobalt-ion-implanted samples. 相似文献
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Study of depth-dependent tetragonal distortion of quaternary AlInGaN epilayer by Rutherford backscattering/channeling 下载免费PDF全文
A 240-nm thick Al0.4In0.02Ga0.58N layer is grown by metal organic chemical vapour deposition, with an over 1-μ m thick GaN layer used as a buffer layer on a substrate of sapphire (0001). Rutherford backscattering and channeling are used to characterize the microstructure of AlInGaN. The results show a good crystalline quality of AlInGaN (χmin=1.5%) with GaN buffer layer. The channeling angular scan around an off-normal <12-13> axis in the {101-0} plane of the AlInGaN layer is used to determine tetragonal distortion eT, which is caused by the elastic strain in the AlInGaN. The resulting AlInGaN is subjected to an elastic strain at interfacial layer, and the strain decreases gradually towards the near-surface layer. It is expected that an epitaxial AlInGaN thin film with a thickness of 850 nm will be fully relaxed (eT = 0). 相似文献
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In this paper, a comprehensive mathematical analysis is carried out on an unsteady boundary-layer flow with heat and mass transfer characteristics of a viscous fluid through porous media. Fluid suction or blowing is assumed to take place at the surface. The governing coupled nonlinear partial differential equations are transformed into coupled nonlinear ordinary differential equations by using a similarity transformation and are solved analytically and numerically by using the homotopy analysis method and the Runge-Kutta and shooting technique, respectively. A comparison between analytical and numerical results is conducted, which shows excellent agreement. 相似文献
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S.?WaheedEmail author S.?Rahman S.?M.?Husnain N.?Siddique 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(3):937-945
Instrumental Neutron Activation Analysis (INAA) and Atomic Absorption Spectroscopy methodology was developed to characterize
the hazardous and other inorganic trace element constituents in new and used domestic plastic food containers. INAA due to
its non destructive, highly sensitive, multielement and low detection limits characteristics was found to be a good technique
for the characterization of polymeric products. Through the variation of irradiation, cooling and counting protocols Al, Ba,
Br, Co, Cr, Eu, Fe, Hg, K, Mn, Na, Nd, Sb, Sc, Th, Ti, V and Zn were determined, while Atomic Absorption Spectroscopy was
used as complementary technique to quantify toxic inorganic elements such as Cd, Pb and Cu. These elements are thought to
originate from the polymer manufacturing processes. It was found that there was gradual increase in the concentration of most
of these elements from new to used plastic samples. Moreover it was also observed that these inorganic elements are present
in higher concentrations in the lower grade containers as compared to the high quality containers. It was also observed that
the good quality containers even with the long usage do not degrade to such an extent as the low quality containers. 相似文献
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G. Husnain Yao Shu-De Ishaq Ahmad Li Lin 《Applied Physics A: Materials Science & Processing》2014,117(4):2275-2279
Chromium ions implantation was performed into metal–organic chemical vapor deposition grown GaN thin film of thickness about 2 µm at 5 × 1016 cm?2 fluence. Implantation was performed at various substrate temperatures (RT, 250, 350 °C). Rapid thermal annealing was employed at 900 °C to remove implantation-induced damages as well as for activation of dopant. Structural study was performed by Rutherford backscattering and channeling spectrometry and high-resolution X-ray diffraction. To confirm magnetic properties at room temperature, hysteresis loops were obtained using alternating gradient magneto-meter. Well-defined hysteresis loops were achieved at 300 K in implanted and annealed samples. Temperature-dependent magnetization indicated magnetic moment at 5 K and retain up to 380 K. 相似文献
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