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19 Feb 2001

Volume 78, Issue 8, pp. 1023-1163

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X-ray determination of vertical ordering of InAs quantum dots in InAs/GaAs multilayers

J. C. González, R. Magalhães-Paniago, W. N. Rodrigues, A. Malachias, M. V. B. Moreira, A. G. de Oliveira, I. Mazzaro, C. Cusatis, T. H. Metzger, and J. Peisl

Appl. Phys. Lett. 78, 1056 (2001); http://dx.doi.org/10.1063/1.1347024 (3 pages) | Cited 7 times

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The degree of vertical alignment of InAs quantum dots in InAs/GaAs(001) multilayers was studied using grazing incidence x-ray scattering. We show that it is necessary to access one of the weak (200) x-ray reflections to observe the modulation of the GaAs lattice periodicity produced by the stacking of the InAs dots. The degree of alignment of the dots was assessed by fitting the x-ray diffuse scattering profiles near a GaAs (200) reciprocal lattice point. By using a model of gaussian lateral displacement of the dots, we show that we can determine the average value of the mistake in stacking positions of the islands from one bilayer to the next. © 2001 American Institute of Physics.
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68.65.Hb Quantum dots (patterned in quantum wells)
78.70.Ck X-ray scattering

Excited-state quenching of a highly luminescent conjugated polymer

C. Belton, D. F. O’Brien, W. J. Blau, A. J. Cadby, P. A. Lane, D. D. C. Bradley, H. J. Byrne, R. Stockmann, and H-H. Hörhold

Appl. Phys. Lett. 78, 1059 (2001); http://dx.doi.org/10.1063/1.1345840 (3 pages) | Cited 19 times

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The optical properties of a luminescent polymer, poly[1,4-phenylene-1,2-di(phenoxyphenyl) vinylene], have been investigated. Its photoluminescence yield increases unusually in the solid-state over solution, 52%–6% respectively. Investigations into the stimulated emission properties of this material were carried out but no amplified spontaneous emission was observed. To investigate the presence of excited-state absorption features, the photoinduced absorption spectrum was measured. An observed polaron absorption band, from 1.5 to 2.25 eV, overlaps the emission spectra and therefore quenches stimulated emission. This highlights the need to consider the effects of excited-state absorption on the emission when synthesizing new materials. © 2001 American Institute of Physics.
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78.55.Kz Solid organic materials
78.66.Qn Polymers; organic compounds
42.70.Jk Polymers and organics
78.40.Me Organic compounds and polymers
71.20.Rv Polymers and organic compounds
78.45.+h Stimulated emission
71.38.-k Polarons and electron-phonon interactions
61.41.+e Polymers, elastomers, and plastics

Time-resolved spectroscopy of strained GaN/AlN/6H–SiC heterostructures grown by metalorganic chemical vapor deposition

G. Pozina, N. V. Edwards, J. P. Bergman, T. Paskova, B. Monemar, M. D. Bremser, and R. F. Davis

Appl. Phys. Lett. 78, 1062 (2001); http://dx.doi.org/10.1063/1.1350421 (3 pages) | Cited 6 times

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Temperature-dependent time-resolved photoluminescence measurements were performed on GaN film/AlN buffer/6H–SiC substrate heterostructures grown by metalorganic chemical vapor deposition. The overlying GaN layers were under tension, as estimated from the free A exciton (FEA) position. The recombination lifetimes were determined for the FEA and for the neutral-donor-bound exciton (D0X). We observed that the recombination lifetime for the FEA has the same value of 40–50 ps in all the layers, whereas the recombination time for the D0X varies for different samples. We observed that the recombination lifetimes for D0X have a clear dependence on the position of FEA, i.e., the recombination lifetime increases with decreasing strain in the layers. We discuss the results in term of the hole states involved in the donor-bound exciton recombination. © 2001 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.47.-p Spectroscopy of solid state dynamics
71.35.-y Excitons and related phenomena
71.55.Eq III-V semiconductors
78.55.Cr III-V semiconductors
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Room-temperature random telegraph noise in luminescence from macroscopic InGaN clusters

Takao Aoki, Yukie Nishikawa, and Makoto Kuwata-Gonokami

Appl. Phys. Lett. 78, 1065 (2001); http://dx.doi.org/10.1063/1.1346630 (3 pages) | Cited 6 times

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We report on photoluminescence properties of individual macroscopically sized InGaN clusters that were formed in InGaN multiple quantum wells. Phase separation in InGaN results in the formation of clusters with a size of 1–2 μm with three different indium compositions. A small fraction (one in 100–1000) of the clusters shows random telegraph noise in luminescence at room temperature. Superlinear dependence of the luminescence switching rate on excitation intensity indicates that the switching is induced by the cooperation of multiple carriers. © 2001 American Institute of Physics.
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78.67.De Quantum wells
78.55.Cr III-V semiconductors
73.21.Fg Quantum wells

Stress-stimulated luminescence from ZnAl2O4:Mn

Hiroaki Matsui, Chao-Nan Xu, and Hiroshi Tateyama

Appl. Phys. Lett. 78, 1068 (2001); http://dx.doi.org/10.1063/1.1350429 (3 pages) | Cited 35 times

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We have investigated the stress-stimulated luminescence (SSL) from ZnAl2O4:Mn. Two kinds of ZnAl2O4:Mn samples were synthesized at different reduction conditions to clarify the influence of the structure defects on the SSL property. The SSL intensity was found to be greatly increased by reducing ZnAl2O4:Mn at a high temperature of 1300 °C. The luminescence integrated intensity was about two magnitudes larger than that of conventional ZnAl2O4:Mn. This enhancement is attributed to a large number of trapped carriers in the reduced ZnAl2O4:Mn from the results of thermoluminescence. The SSL spectrum was consistent with the photoluminescence spectrum as well as the afterglow one. It is suggested that the trapped carriers can be excited by stress, and the resultant recombination between excited electrons and holes give rise to an energy which can be transferred to Mn2+ centers to create emission according to the transitions of 4T1 to 6A1. © 2001 American Institute of Physics.
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78.60.Mq Sonoluminescence, triboluminescence
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects
78.60.Kn Thermoluminescence
78.55.Hx Other solid inorganic materials
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
61.72.-y Defects and impurities in crystals; microstructure

Spike annealing of boron-implanted polycrystalline-silicon on thin SiO2

A. T. Fiory, K. K. Bourdelle, and P. K. Roy

Appl. Phys. Lett. 78, 1071 (2001); http://dx.doi.org/10.1063/1.1348307 (3 pages) | Cited 4 times

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Spike thermal annealing is examined for electrical activation of B implants into 100 nm Si films deposited over 1.5 to 2.4 nm thermally grown SiO2. These structures simulate gate stacks in advanced p-type metal–oxide–Si (PMOS) devices. Spike anneals, at minimized thermal budget, are shown to yield higher carrier concentrations in PMOS polycrystalline-silicon (poly-Si), as compared to conventional rapid thermal annealing. The activation energy for B diffusion through SiO2 is found to be 3.71 to 3.83 eV and near that previously reported for furnace anneals. Boron penetration appears unaffected by photoexcitation from heating lamps. © 2001 American Institute of Physics.
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61.72.Cc Kinetics of defect formation and annealing
61.72.uf Ge and Si
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
85.40.Ry Impurity doping, diffusion and ion implantation technology

Observation of crossing pores in anodically etched n-GaAs

S. Langa, J. Carstensen, M. Christophersen, H. Föll, and I. M. Tiginyanu

Appl. Phys. Lett. 78, 1074 (2001); http://dx.doi.org/10.1063/1.1350433 (3 pages) | Cited 34 times

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Pores in GaAs in the micrometer range and oriented in 〈111〉 directions have been observed during the anodization of GaAs in aqueous HCl electrolytes. A direct evidence of pores intersection is presented which is a very promising feature for three-dimensional micro- and nanostructuring of III–V compounds for the production of photonic materials. © 2001 American Institute of Physics.
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73.61.Ey III-V semiconductors
81.05.Ea III-V semiconductors
81.65.Cf Surface cleaning, etching, patterning
68.35.B- Structure of clean surfaces (and surface reconstruction)

Synthesis of InNxP1−x thin films by N ion implantation

K. M. Yu, W. Walukiewicz, J. Wu, J. W. Beeman, J. W. Ager, E. E. Haller, W. Shan, H. P. Xin, and C. W. Tu

Appl. Phys. Lett. 78, 1077 (2001); http://dx.doi.org/10.1063/1.1350963 (3 pages) | Cited 21 times

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Dilute InNxP1−x alloy thin films were synthesized by nitrogen ion implantation into InP using doses corresponding to N mole fraction up to 0.048. In the films with the highest N contents, it was shown using modulated photoreflectance that the fundamental band gap energy was decreased by up to 180 meV. The band gap reduction is similar in magnitude to that observed in epitaxially grown III–NxV1−x alloys. The InNxP1−x layers were thermally stable up to an annealing temperature of 850 °C. Using the recently developed band anticrossing model which relates the band gap reduction to the N content, we estimate that the maximum mole fraction of N achieved in the InNxP1−x alloys is larger than that reported previously for film grown by chemical vapor deposition and exceeds 0.01. © 2001 American Institute of Physics.
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61.72.uj III-V and II-VI semiconductors
81.05.Ea III-V semiconductors
61.72.Cc Kinetics of defect formation and annealing
78.66.Fd III-V semiconductors
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Initial stages of molecular-beam epitaxy growth of GaN on 6H-SiC(0001)

J. Lu, L. Haworth, D. I. Westwood, and J. E. Macdonald

Appl. Phys. Lett. 78, 1080 (2001); http://dx.doi.org/10.1063/1.1350430 (3 pages) | Cited 15 times

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We studied the atomic H etching of 6H-SiC substrates and the initial stages of GaN/6H-SiC molecular-beam epitaxy growth. Atomic H etched 6H-SiC(0001)Si and (000math)C surfaces show a (√×√)−R30° and a (1×1) reconstruction respectively, with 0.7±0.2 monolayers of remnant O on both surfaces. GaN/6H-SiC(0001)Si growth is initiated by the formation of islands that develop into flat-top terraces through coalescence. Growth steps of one or integer numbers of the GaN atomic bilayer height are observed. GaN grown on 6H-SiC(000math)C is rougher with islands of irregular shape. X-ray photoemission spectroscopy studies show that Si 2p and C 1s photoelectron inelastic mean free paths in GaN are 22±1 and 20±1 Å, respectively. © 2001 American Institute of Physics.
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81.05.Ea III-V semiconductors
68.55.-a Thin film structure and morphology
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.35.B- Structure of clean surfaces (and surface reconstruction)
81.65.Cf Surface cleaning, etching, patterning
52.77.Bn Etching and cleaning
79.60.Bm Clean metal, semiconductor, and insulator surfaces
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