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13 May 2002

Volume 80, Issue 19, pp. 3467-3650

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Optical properties of ZnO thin films: Ion layer gas reaction compared to sputter deposition

M. Rebien, W. Henrion, M. Bär, and Ch.-H. Fischer

Appl. Phys. Lett. 80, 3518 (2002); http://dx.doi.org/10.1063/1.1479211 (3 pages) | Cited 15 times

Online Publication Date: 7 May 2002

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Zinc oxide films prepared by the recently developed ion layer gas reaction (ILGAR) technique and by rf magnetron sputtering are compared with respect to their linear optical properties. Spectral ellipsometry as well as reflectance and transmittance measurements in the UV-visible-near infrared range were employed to deduce the complex refractive index. The band gap energy, Urbach energy, and packing density were determined. The results are compared to literature data of single crystals and thin films. © 2002 American Institute of Physics.
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78.66.Hf II-VI semiconductors
81.05.Dz II-VI semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.30.Fs III-V and II-VI semiconductors
78.40.Fy Semiconductors
81.15.Cd Deposition by sputtering
71.20.Nr Semiconductor compounds

Influence of GaN domain size on the electron mobility of two-dimensional electron gases in AlGaN/GaN heterostructures determined by x-ray reflectivity and diffraction

Zhenyang Zhong, O. Ambacher, A. Link, V. Holy, J. Stangl, R. T. Lechner, T. Roch, and G. Bauer

Appl. Phys. Lett. 80, 3521 (2002); http://dx.doi.org/10.1063/1.1479206 (3 pages) | Cited 13 times

Online Publication Date: 7 May 2002

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X-ray reflectivity and diffraction measurements were performed on Ga-face AlGaN/GaN heterostructures to determine the influence of interface roughness scattering and GaN domain boundaries scattering on the electron mobility of polarization induced two-dimensional electron gases. From simulations of the specular reflectivity, the root-mean-square roughness of the AlGaN/GaN interfaces was obtained. In reciprocal space maps, laterally elongated streaks passing through the Bragg peaks have been observed, which are attributed to column-like domains in the GaN buffer layers. The relationship between electron mobility measured by Hall effect and the interface roughness on one hand, and the column domain size on the other hand, demonstrates that the interface roughness scattering is not limiting the electron mobility, whereas the transport properties of the two-dimensional electron gas degrade with decreasing size of columnar domains in the GaN layer. © 2002 American Institute of Physics.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
68.35.Ct Interface structure and roughness
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.20.At Surface states, band structure, electron density of states

Microscopic correlation of redshifted luminescence and surface defects in thick InxGa1−xN layers

F. Bertram, S. Srinivasan, L. Geng, F. A. Ponce, T. Riemann, and J. Christen

Appl. Phys. Lett. 80, 3524 (2002); http://dx.doi.org/10.1063/1.1479199 (3 pages) | Cited 12 times

Online Publication Date: 7 May 2002

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A direct correlation between the structural and luminescence properties of thick InxGa1−xN layers has been achieved on a microscopic scale using highly spatially resolved cathodoluminescence. Surface roughening is typically observed in growth by metalorganic vapor phase epitaxy of thick InxGa1−xN layers for x⩾0.1. Although the film remains highly planar, craters and protrusions appear on the surface. These surface defects are associated with redshifted luminescence indicative of indium segregation, and are related to threading dislocations in the films. © 2002 American Institute of Physics.
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68.35.Dv Composition, segregation; defects and impurities
81.05.Ea III-V semiconductors
68.55.A- Nucleation and growth
78.66.Fd III-V semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.35.B- Structure of clean surfaces (and surface reconstruction)
78.60.Hk Cathodoluminescence, ionoluminescence
64.75.-g Phase equilibria

Separation of optical anisotropies by angular dependent reflection anisotropy spectroscopy

B. F. Macdonald and R. J. Cole

Appl. Phys. Lett. 80, 3527 (2002); http://dx.doi.org/10.1063/1.1478784 (3 pages) | Cited 14 times

Online Publication Date: 7 May 2002

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Double rubbing of polymer films, which finds applications in modern liquid crystal devices, has been investigated using reflection anisotropy spectroscopy (RAS) and atomic force microscopy. A method of gauging the relative strength of rubbing in two different directions, based upon the dependence of observed RAS signals on the sample azimuthal angle, has been found. Angular dependent measurements are shown to be a useful extension of the standard technique by allowing angular dependent sources of optical anisotropy to be separated experimentally. © 2002 American Institute of Physics.
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78.66.Qn Polymers; organic compounds
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
78.20.Fm Birefringence
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Ps Atomic force microscopy (AFM)

Fluorine interaction with point defects, boron, and arsenic in ion-implanted Si

Ali Mokhberi, Reza Kasnavi, Peter B. Griffin, and James D. Plummer

Appl. Phys. Lett. 80, 3530 (2002); http://dx.doi.org/10.1063/1.1479458 (3 pages) | Cited 23 times

Online Publication Date: 7 May 2002

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The role of fluorine in suppressing boron diffusion was investigated by utilizing a buried dopant marker to monitor the interaction of fluorine with interstitials. A boron spike with a peak concentration of 1.2×1018 cm−3 followed by 500 nm of undoped silicon was grown in a low pressure chemical vapor deposition furnace. The wafers were then preamorphized and implanted with either B, B and F, BF2, As, As and F, or F, respectively. Following the implants, the samples were rapid thermal annealed (RTA) at 1050 °C for very short times (spike). The use of preamorphization allows the chemical effect of fluorine to be analyzed independently of implant damage, and the buried layer functions as an indicator of point defect (in this case Si self-interstitial) perturbation. As expected, secondary ion mass spectroscopy shows that the presence of fluorine retards the diffusion of boron. In addition, the retained fluorine dose after the RTA is highest in the boron-implanted samples. In all samples the buried layer has diffused by the same amount, indicating that there is no change to the silicon self-interstitial population due to fluorine. These results suggest that fluorine has a chemical effect, and retards boron diffusion by mainly bonding with boron. © 2002 American Institute of Physics.
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61.72.Yx Interaction between different crystal defects; gettering effect
61.72.uf Ge and Si
61.72.S- Impurities in crystals
66.30.J- Diffusion of impurities
61.72.J- Point defects and defect clusters
61.72.Cc Kinetics of defect formation and annealing

Magneto-thermal shape memory effect in Ni–Mn–Ga

N. Glavatska, I. Glavatsky, G. Mogilny, and V. Gavriljuk

Appl. Phys. Lett. 80, 3533 (2002); http://dx.doi.org/10.1063/1.1478130 (3 pages) | Cited 4 times

Online Publication Date: 7 May 2002

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A way to produce shape memory in Ni–Mn–Ga alloys is proposed based on the combined action of the magnetic field and heating. A sample is magnetized under applied magnetic field, which results in the magnetic-field-induced strain caused by the reorientation of martensitic domains so that the tetragonal axis c (axis of easy magnetization) is oriented in direction of the applied field. Thereafter the field is switched off and the sample is heated above the Curie temperature and cooled to the start temperature of the experiment, which leads to the full recovery of the size and structure existing before the action of magnetic field. This effect is explained based on the data of x-ray diffraction studies. © 2002 American Institute of Physics.
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81.30.Kf Martensitic transformations
75.80.+q Magnetomechanical effects, magnetostriction
81.05.Bx Metals, semimetals, and alloys
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
64.70.K- Solid-solid transitions
75.60.Ch Domain walls and domain structure
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Far-infrared absorption in Sb-doped Ge epilayers near the metal–insulator transition

Jordana Bandaru, Jeffrey W. Beeman, and Eugene E. Haller

Appl. Phys. Lett. 80, 3536 (2002); http://dx.doi.org/10.1063/1.1479203 (3 pages) | Cited 2 times

Online Publication Date: 7 May 2002

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Epitaxial germanium layers doped near the metal–insulator transition were grown by liquid phase epitaxy from a Pb melt. Far-infrared absorption was measured between ∼20 cm−1 and 150 cm−1. Linear optical absorption coefficients were determined for Ge:Sb in the doping range of 9.0×1014 cm−3<ND<6.7×1016 cm−3. The peak absorption was found to increase linearly with dopant concentration as expected. The absorption at ∼50 cm−1 increased superlinearly with Sb concentration as a result of impurity banding. The optimal Sb concentration for extended far-infrared photoconductive response (λ>200 μm) in blocked impurity band detectors is discussed. © 2002 American Institute of Physics.
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78.66.Db Elemental semiconductors and insulators
78.30.Am Elemental semiconductors and insulators
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
73.61.Cw Elemental semiconductors
71.30.+h Metal-insulator transitions and other electronic transitions
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Photoluminescence study of hydrogen passivation in InAs1−xNx/InGaAs single-quantum well on InP

Y. Y. Ke, M. H. Ya, Y. F. Chen, J. S. Wang, and H. H. Lin

Appl. Phys. Lett. 80, 3539 (2002); http://dx.doi.org/10.1063/1.1476383 (3 pages) | Cited 2 times

Online Publication Date: 7 May 2002

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It is well known that nitrogen incorporation into III–V compounds will degrade the quality of materials. In this letter, we show that the incorporation of atomic hydrogen into InAsN/InGaAs quantum wells can effectively passivate defects and lead to enhancement of photoluminescence intensity near the band edge. After hydrogenation, the change of the optical properties is quite different from that of the annealing with nitrogen treatment. For instance, the linewidth becomes wider after hydrogenation, while the linewidth is narrower after nitrogen annealing. Through a detailed study of the photoluminescence spectra, we show that the passivation of defect bonds is the main reason for the improved optical behavior for hydrogenation, while the interdiffusion is responsible for the change after nitrogen annealing. © 2002 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.67.De Quantum wells
61.72.Cc Kinetics of defect formation and annealing
68.65.Fg Quantum wells
66.30.Ny Chemical interdiffusion; diffusion barriers
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