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2 Jan 2006

Volume 88, Issue 1, Articles (01xxxx)

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Appl. Phys. Lett. 88, 011112 (2006); http://dx.doi.org/10.1063/1.2161387 (3 pages)

Yoshinori Tanaka, Takashi Asano, Ranko Hatsuta, and Susumu Noda
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Co–Fe–B–Si–Nb bulk glassy alloys with superhigh strength and extremely low magnetostriction

Chuntao Chang, Baolong Shen, and Akihisa Inoue

Appl. Phys. Lett. 88, 011901 (2006); http://dx.doi.org/10.1063/1.2159107 (3 pages) | Cited 28 times

Online Publication Date: 3 January 2006

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Co-based bulk glassy alloys with diameters up to 4 mm were formed in a [(Co1−xFex)0.75B0.2Si0.05]96Nb4 system. The bulk glassy alloys exhibit a superhigh fracture strength of 3980–4170 MPa and Young’s modulus of 190–210 GPa. The bulk glassy alloys also exhibit excellent soft-magnetic properties, i.e., high saturation magnetization of 0.71–0.97 T, low coercive force of 0.7–1.8 A/m, high permeability of 1.48–3.25×104, and extremely low saturation magnetostriction of 0.55–5.76×10−6. The first successful synthesis of the Co–Fe–B–Si-based bulk glassy alloys exhibiting superhigh fracture strength and excellent soft-magnetic properties with extremely low magnetostriction is encouraging for future development of Co-based bulk glassy alloys as new engineering and functional materials.
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81.05.Kf Glasses (including metallic glasses)
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.M- Structural failure of materials
75.80.+q Magnetomechanical effects, magnetostriction
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

High-quality m-plane GaN thin films deposited on γ-LiAlO2 by ion-beam-assisted molecular-beam epitaxy

J. W. Gerlach, A. Hofmann, T. Höche, F. Frost, B. Rauschenbach, and G. Benndorf

Appl. Phys. Lett. 88, 011902 (2006); http://dx.doi.org/10.1063/1.2159100 (3 pages) | Cited 13 times

Online Publication Date: 3 January 2006

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GaN(1math00) thin films are deposited on γ-LiAlO2(100) by low-energy-ion-beam-assisted molecular-beam epitaxy. Structural properties of the epitaxial GaN films are investigated by x-ray diffraction, transmission electron microscopy, and atomic force microscopy. X-ray diffraction measurements give evidence for a high crystalline quality far better than previously reported in literature. Cross-section transmission electron microscopy and atomic force microscopy show an anisotropy in defect structure and surface topography parallel and perpendicular to the GaN c axis. Optical properties are examined by photoluminescence spectroscopy at various temperatures. The spectra exhibit a strong and sharp near-band-gap transition, as well as a donor-acceptor pair transition.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.15.Jj Ion and electron beam-assisted deposition; ion plating
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
68.37.Lp Transmission electron microscopy (TEM)
68.37.Ps Atomic force microscopy (AFM)

Influence of structural nonuniformity and nonradiative processes on the luminescence efficiency of InGaAsN quantum wells

L. Geelhaar, M. Galluppi, G. Jaschke, R. Averbeck, H. Riechert, T. Remmele, M. Albrecht, M. Dworzak, R. Hildebrant, and A. Hoffmann

Appl. Phys. Lett. 88, 011903 (2006); http://dx.doi.org/10.1063/1.2159566 (3 pages) | Cited 12 times

Online Publication Date: 3 January 2006

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We compare the luminescence efficiency (i.e., room-temperature photoluminescence intensity), fluctuations in composition and thickness, degree of localization, and luminescence decay times of In0.37Ga0.63As0.983N0.017 quantum wells grown by molecular-beam epitaxy at different temperatures and annealed under a comprehensive variety of conditions. Luminescence efficiency is not directly coupled to structural nonuniformity or localization, and even three-dimensional growth is not detrimental by itself. In contrast, there is always a correlation between luminescence efficiency and nonradiative decay time. Therefore, the luminescence efficiency of InGaAsN quantum wells depends almost exclusively on the density of nonradiative recombination centers, while the influence of structural nonuniformity is negligible.
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78.67.De Quantum wells
78.55.Cr III-V semiconductors
61.72.Cc Kinetics of defect formation and annealing

Investigation of silicon diffusion into yttrium using x-ray photoelectron spectroscopy

S. Y. Chiam, W. K. Chim, A. C. H. Huan, J. S. Pan, and J. Zhang

Appl. Phys. Lett. 88, 011904 (2006); http://dx.doi.org/10.1063/1.2159567 (3 pages) | Cited 3 times

Online Publication Date: 3 January 2006

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The reactions of yttrium (Y) metal on silicon (Si) are investigated by x-ray photoelectron spectroscopy (XPS). Low-temperature annealing studies are performed to investigate the diffusion of Si. It is found that Si diffusion occurs even under low annealing temperatures of <300 °C in an ultrahigh vacuum environment. This is attributed to the weakening of the Si–Si covalent bonds by metallic Y. XPS depth profiling of room-temperature-oxidized films revealed a possible oxygen-mediated pathway which allowed significant Si diffusion at room temperature for silicate formation.
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66.30.J- Diffusion of impurities
79.60.Bm Clean metal, semiconductor, and insulator surfaces
61.72.S- Impurities in crystals
61.72.Cc Kinetics of defect formation and annealing

Thermomechanical criteria for overlay alignment in flexible thin-film electronic circuits

Helena Gleskova, I-Chun Cheng, Sigurd Wagner, and Zhigang Suo

Appl. Phys. Lett. 88, 011905 (2006); http://dx.doi.org/10.1063/1.2161391 (3 pages) | Cited 8 times

Online Publication Date: 3 January 2006

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A simple mechanical model for a deposited film∕substrate couple is presented to describe how film deposition at an elevated temperature induces change in the substrate’s in-plane dimensions at room temperature. The model provides a quantitative guideline for reducing, or completely eliminating, this elongation, by tailoring the tensile built-in stress in the deposited film. The dimensional stability so achieved is necessary for accurate overlay alignment of photomasks during the fabrication of thin-film electronic circuits.
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85.40.Sz Deposition technology

Fluorescence upconversion in Sm-doped Gd2O3

D. Dosev, I. M. Kennedy, M. Godlewski, I. Gryczynski, K. Tomsia, and E. M. Goldys

Appl. Phys. Lett. 88, 011906 (2006); http://dx.doi.org/10.1063/1.2161400 (3 pages) | Cited 26 times

Online Publication Date: 3 January 2006

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We report the observation of efficient fluorescence upconversion in Sm-doped Gd2O3 nanopowders prepared by the spray pyrolysis method. The blue upconversion emission was observed with low-power continuous-wave excitation at 514, 561, 594, and 633 nm and with a pulsed femtosecond at 710 nm, in a laser scanning confocal microscope. This result indicates that Sm-doped Gd2O3 has the potential as a fluorescent label that may be excited in red, yellow, and green with blue emission.
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81.07.Wx Nanopowders
78.55.Hx Other solid inorganic materials
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.47.-p Spectroscopy of solid state dynamics
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
81.16.Be Chemical synthesis methods

Experimental demonstration of the relationship between the OH− content and photoluminescence in Tb-doped YPO4∙2H2O

Weihua Di, Xiaojun Wang, Baojiu Chen, Shaozhe Lu, and Xinguang Ren

Appl. Phys. Lett. 88, 011907 (2006); http://dx.doi.org/10.1063/1.2158703 (3 pages) | Cited 9 times

Online Publication Date: 3 January 2006

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Tb-doped YPO4∙2H2O was synthesized via a simple wet-chemical route. Both the crystallinity of samples and the concentration of OH− adsorbed at the surface were experimentally controlled by adjusting the reaction time. An abnormal phenomenon that photoluminescence efficiency decreases with the increase of crystallinity demonstrates enormously adverse effect of OH− on photoluminescence, especially, as the OH− content reaches a critical value, the luminescent efficiency decreases more drastically. This strong dependence of photoluminescence on the OH− content indicates that to control the OH− content in a limited range or to reduce the OH− effect as much as possible is an efficient way to improve photoluminescence efficiency.
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78.55.Hx Other solid inorganic materials
68.43.Mn Adsorption kinetics

Epitaxy of nonpolar AlN on 4H-SiC (1-100) substrates

R. Armitage, J. Suda, and T. Kimoto

Appl. Phys. Lett. 88, 011908 (2006); http://dx.doi.org/10.1063/1.2161809 (3 pages) | Cited 19 times

Online Publication Date: 4 January 2006

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AlN has been grown on 4H-SiC (1-100) substrates by rf-plasma molecular beam epitaxy. The epilayers assume a metastable 4H structure to match the in-plane stacking arrangement of the substrate. Initial two-dimensional nucleation of 4H-AlN is revealed by reflection high-energy electron diffraction. The epitaxial quality is evidenced by narrow x-ray diffraction ω-scan linewidths less than 70 arcsec for both symmetric and asymmetric reflections. The AlN growth surface exhibits a smooth and anisotropic morphology similar to that of GaN (1-100). Large residual stress is present in the epilayers, consistent with incomplete relaxation of misfit strain during growth.
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81.05.Ea III-V semiconductors
68.55.-a Thin film structure and morphology
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.47.Fg Semiconductor surfaces
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.60.Bs Mechanical and acoustical properties

Change in cation nonstoichiometry at interfaces during crystal growth in polycrystalline BaTiO3

Si-Young Choi, Suk-Joong L. Kang, Sung-Yoon Chung, Takahisa Yamamoto, and Yuichi Ikuhara

Appl. Phys. Lett. 88, 011909 (2006); http://dx.doi.org/10.1063/1.2162680 (3 pages) | Cited 5 times

Online Publication Date: 4 January 2006

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Using an embedded single crystal in a polycrystalline matrix and quantitative electron energy loss spectroscopy, we have demonstrated that Ti-excess grain boundary nonstoichiometry can vary with the extent of boundary migration. While a slight excess in Ti was detected at the boundaries between small matrix grains, a large increase in Ti/Ba ratio, to as much as ∼ 1.50 compared to the stoichiometric value, was present at the interface between a growing single crystal and the matrix grains when the embedded crystal grew up to a few hundred micrometers. This change in nonstoichiometry was attributed to a continuous accumulation of excessive Ti at the moving boundary during crystal growth. The present result indicates that growth kinetics can critically affect the interface chemistry in polycrystals.
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61.66.Bi Elemental solids
61.66.Dk Alloys
79.20.Uv Electron energy loss spectroscopy
61.72.Mm Grain and twin boundaries
66.30.Lw Diffusion of other defects
66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Fx Diffusion; interface formation

High conductivity of Ga-doped rock-salt ZnO under pressure: Hint on deep-ultraviolet-transparent conducting oxides

A. Segura, J. A. Sans, D. Errandonea, D. Martinez-García, and V. Fages

Appl. Phys. Lett. 88, 011910 (2006); http://dx.doi.org/10.1063/1.2161392 (3 pages) | Cited 21 times

Online Publication Date: 4 January 2006

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This letter reports on transport and optical experiments under pressure in thin films of Ga-doped ZnO in both the wurtzite and rock-salt phases. The conductivity of heavily Ga-doped ZnO thin films is shown to decrease by only a factor of 2 in the wurtzite-to-rock-salt phase transition, occurring at about 11.5 GPa, while the optical gap increases from 4 to more than 5 eV. Ga-doped rock-salt ZnO is shown to behave as a deep-ultraviolet-transparent conducting oxide, with resistivity values as low as 10−3 Ω cm. The analysis of Burstein–Moss shift and free carrier absorption in rock-salt ZnO yield an estimation of the electron-hole reduced effective mass and electronic dielectric constant. Given the similarity between the electronic structures of rock-salt ZnO under pressure and rock-salt MgxZn1−xO at ambient pressure, this alloy could be a good deep-ultraviolet-transparent conducting oxide.
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81.05.Dz II-VI semiconductors
73.61.Ga II-VI semiconductors
78.66.Hf II-VI semiconductors
62.50.-p High-pressure effects in solids and liquids
68.55.A- Nucleation and growth
61.72.uj III-V and II-VI semiconductors

Reduced electronegativity difference as a factor leading to the formation of Al-based glassy alloys with a large supercooled liquid region of 50 K

Dmitri V. Louzguine-Luzgin, Akihisa Inoue, and Walter José Botta

Appl. Phys. Lett. 88, 011911 (2006); http://dx.doi.org/10.1063/1.2159420 (3 pages) | Cited 17 times

Online Publication Date: 4 January 2006

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The influence of the electronegativity difference among the constituent elements on the stability of the supercooled liquid in two Al-based glassy alloys is studied. A record-large value of the supercooled liquid region of about 50 K is obtained based on the electronegativity difference concept within a certain composition range.
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81.05.Kf Glasses (including metallic glasses)
61.43.Fs Glasses
64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition

Nonradiative recombination effect on photoluminescence decay dynamics in GaInNAs/GaAs quantum wells

Z. Sun, Z. Y. Xu, X. D. Yang, B. Q. Sun, Y. Ji, S. Y. Zhang, H. Q. Ni, and Z. C. Niu

Appl. Phys. Lett. 88, 011912 (2006); http://dx.doi.org/10.1063/1.2161071 (3 pages) | Cited 4 times

Online Publication Date: 4 January 2006

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The influence of nonradiative recombination on the photoluminescence (PL) decay dynamics in GaInNAs/GaAs quantum wells is studied by time-resolved photoluminescence under various excitation intensities. It is found that the PL decay process strongly depends on the excitation intensity. In particular, under the moderate excitation levels the PL decay curves exhibit unusual nonexponential behavior and show a convex shape. By introducing a new parameter of the effective concentration of nonradiative recombination centers into a rate equation, the observed results are well simulated. The cw PL data further demonstrate the nonradiative recombination effect on the optical properties of GaInNAs/GaAs quantum wells.
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78.55.Cr III-V semiconductors
78.47.-p Spectroscopy of solid state dynamics
78.67.De Quantum wells

Adatom-assisted structural transformations of fullerenes

In-Ho Lee, Sukky Jun, Hanchul Kim, Sung Youb Kim, and Youngmin Lee

Appl. Phys. Lett. 88, 011913 (2006); http://dx.doi.org/10.1063/1.2161175 (3 pages) | Cited 10 times

Online Publication Date: 4 January 2006

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Microscopic mechanism of autocatalytic structural transformations of fullerenes is investigated by the action-derived molecular dynamics. Dynamic pathways and the corresponding activation energies are obtained for the Stone-Wales transformation in fullerene and the fullerene coalescence, under the presence of extra carbon atoms. The adatom-assisted Stone-Wales transformation is proved to be a highly probable process unit for the structural transformations and annealing treatments of carbon-based graphitic networks. The complex processes of adatom-assisted fullerene coalescence, yielding very low activation energies, are presented.
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61.48.-c Structure of fullerenes and related hollow and planar molecular structures
64.70.K- Solid-solid transitions
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
61.43.Bn Structural modeling: serial-addition models, computer simulation
81.40.Gh Other heat and thermomechanical treatments

Photoluminescence of Ge(Si) self-assembled islands embedded in a tensile-strained Si layer

M. V. Shaleev, A. V. Novikov, A. N. Yablonskiy, Y. N. Drozdov, D. N. Lobanov, Z. F. Krasilnik, and O. A. Kuznetsov

Appl. Phys. Lett. 88, 011914 (2006); http://dx.doi.org/10.1063/1.2158506 (3 pages) | Cited 7 times

Online Publication Date: 5 January 2006

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We report photoluminescence (PL) studies of Ge(Si) self-assembled islands embedded into a tensile-strained Si layer grown on smooth relaxed Si0.75Ge0.25/Si(001) buffer layers subjected to chemical-mechanical polishing. The intense PL from Ge(Si) islands embedded into a strained Si layer compared to the PL from islands grown on unstrained Si(001) is associated with efficient confinement of electrons in a strained Si layer on the heterojunction with islands. The observed dependence of the island PL peak position on thickness of strained Si layer confirms the validity of the model for real-space indirect optical transition between electrons confined in the strained Si layer, and holes localized in islands.
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78.67.-n Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
78.55.Hx Other solid inorganic materials

Atomistic modeling of surface alloy ordering and segregation in the Fe–Pt system

Guillermo Bozzolo, Rosa Alejandra Lukaszew, and Jorge E. Garcés

Appl. Phys. Lett. 88, 011915 (2006); http://dx.doi.org/10.1063/1.2158515 (3 pages) | Cited 6 times

Online Publication Date: 5 January 2006

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A unified description of Pt segregation in Fe–Pt alloys and alloy ordering after Fe deposition on a Pt substrate is provided. Atomistic modeling using the Bozzolo–Ferrante–Smith quantum approximate method for alloys explains the mechanisms leading to full Pt segregation in the first case and a stable mixed Fe–Pt surface with subsurface ordering in the second.
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64.75.-g Phase equilibria
61.50.Ah Theory of crystal structure, crystal symmetry; calculations and modeling

Effect of Al∕N flux ratio during nucleation layer growth on the microstructure of GaN films grown by molecular-beam epitaxy

Lin Zhou, David J. Smith, D. F. Storm, D. S. Katzer, S. C. Binari, and B. V. Shanabrook

Appl. Phys. Lett. 88, 011916 (2006); http://dx.doi.org/10.1063/1.2162670 (3 pages) | Cited 4 times

Online Publication Date: 5 January 2006

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The microstructure of AlN nucleation layers grown on semi-insulating 4H-SiC substrates by plasma-assisted molecular beam epitaxy has a major effect on subsequent GaN and AlGaN∕GaN film quality and electronic properties. Characterization by transmission electron microscopy shows that the morphology of the GaN films is critically dependent on the Al to active nitrogen flux ratio used during nucleation layer growth. Structures grown with Al∕N flux ratios slightly above approximately 0.98 have many basal-plane stacking faults in the AlN nucleation layer, the GaN∕AlN interfaces are wavy and ill defined, and regions of cubic GaN exist close to the GaN∕AlN interfaces. In comparison, for structures grown with lower Al∕N flux ratios, the AlN nucleation layers have no stacking faults and the GaN∕AlN interfaces are sharp. The impact of these changes in microstructure on the electron Hall mobility and buffer leakage are discussed.
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68.55.A- Nucleation and growth
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.-a Thin film structure and morphology
81.05.Ea III-V semiconductors
68.37.Lp Transmission electron microscopy (TEM)
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)

Photorefractive nematic liquid crystals with gain of constant sign under alternating voltage

Tero Kesti and Attilio Golemme

Appl. Phys. Lett. 88, 011917 (2006); http://dx.doi.org/10.1063/1.2159569 (3 pages) | Cited 4 times

Online Publication Date: 5 January 2006

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Two-beam coupling gain of constant sign was observed in hybrid planar/homeotropic nematic cells under a nonbiased square-wave ac field. Charge photogeneration was induced by using one layer of photoconducting polymer. With writing beams of equal intensities, gains up to 6% were observed in ∼ 10 μm thick samples when the amplitude of the applied field was of the order of 1 V μm−1 at 10 Hz. The gain decreased gradually when the frequency was increased, vanishing above 100 Hz.
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42.70.Df Liquid crystals
61.30.-v Liquid crystals
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.70.Gi Light-sensitive materials
42.70.Jk Polymers and organics

Role of intrinsic defects in the electronic and optical properties of α-HgI2

F. Ayres, L. V. C. Assali, W. V. M. Machado, and J. F. Justo

Appl. Phys. Lett. 88, 011918 (2006); http://dx.doi.org/10.1063/1.2159573 (3 pages) | Cited 6 times

Online Publication Date: 5 January 2006

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We investigated the role of intrinsic defects in the electronic and optical properties of mercuric iodide using ab initio methods. The calculations were performed using the total energy all electron methodology, considering full atomic relaxation. We computed the band structure, spin, formation and transition energies, and the dielectric function of isolated iodine and mercury vacancies in several charge states. Our results were compared to available experimental data on photoluminescence and photoplasticity in HgI2. We propose a microscopic model which can explain most of the data on those luminescent centers, unifying experimental results which suggested conflicting conclusions.
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61.72.J- Point defects and defect clusters
71.15.Nc Total energy and cohesive energy calculations
71.20.Ps Other inorganic compounds
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.55.Hx Other solid inorganic materials

Radiative recombination of GaInNP alloys lattice matched to GaAs

M. Izadifard, J. P. Bergman, W. M. Chen, I. A. Buyanova, Y. G. Hong, and C. W. Tu

Appl. Phys. Lett. 88, 011919 (2006); http://dx.doi.org/10.1063/1.2161118 (3 pages) | Cited 7 times

Online Publication Date: 5 January 2006

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cw- and time-resolved photoluminescence (PL) spectroscopy is employed to evaluate dominant mechanisms for light emission in GayIn1−yNxP1−x alloys grown by gas source molecular-beam epitaxy on GaAs substrates. Different from other direct band gap dilute nitrides, the low temperature PL emission was shown to be largely attributed to radiative transitions involving spatially separated localized electron-hole pairs. The observed charge separation is tentatively attributed to the long range CuPt ordering promoted by the presence of nitrogen.
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78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
78.47.-p Spectroscopy of solid state dynamics

Decoration of buried surfaces in Si detected by positron annihilation spectroscopy

R. S. Brusa, C. Macchi, S. Mariazzi, G. P. Karwasz, W. Egger, P. Sperr, and G. Kögel

Appl. Phys. Lett. 88, 011920 (2006); http://dx.doi.org/10.1063/1.2162691 (3 pages) | Cited 4 times

Online Publication Date: 6 January 2006

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The terminations of buried surfaces of two different cavity types (nano- and microcavities) produced in the same He+–H+ co-implanted p-type Si (100) sample annealed at 900 °C, are studied and characterized by positron annihilation spectroscopy. The characterization was carried out by means of three complementary positron techniques: Doppler broadening and coincidence-Doppler broadening spectroscopy with a continuous slow positron beam, and lifetime spectroscopy with a pulsed slow positron beam. It was found that the nanocavities have a pristine surface of Si, while the surfaces of the microcavities, formed below protruding blisters, are oxygen decorated. This case study opens the interesting use of the positron spectroscopy tool in the topical subject of empty space for microelectronics applications.
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61.72.J- Point defects and defect clusters
61.72.Qq Microscopic defects (voids, inclusions, etc.)
71.60.+z Positron states
78.70.Bj Positron annihilation

Photoluminescence and cathodoluminescence analyses of GaN powder doped with Eu

Huaqiang Wu, Carl B. Poitras, Michal Lipson, Michael G. Spencer, Janet Hunting, and Francis J. DiSalvo

Appl. Phys. Lett. 88, 011921 (2006); http://dx.doi.org/10.1063/1.2162667 (3 pages) | Cited 15 times

Online Publication Date: 6 January 2006

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A high yield process to produce gallium nitride (GaN) powder doped with europium (Eu) is presented. Eu is in situ incorporated into GaN powder through the reaction between a molten alloy of Ga and Eu along with NH3 at 1000 °C using Bi as a wetting agent. This procedure provides a method to produce a GaN:Eu phosphor with high yield and low cost. Room temperature photoluminescence (PL) measurements are studied on GaN:Eu powders with different Eu concentrations. The maximum PL intensity is obtained at a Eu concentration of 1.25 at. %. Cathodoluminescence spectra at room temperature exhibit many detailed transitions in the 530–630 nm range.
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78.55.Cr III-V semiconductors
78.60.Hk Cathodoluminescence, ionoluminescence
61.72.uj III-V and II-VI semiconductors
81.05.Ea III-V semiconductors

Energy of excitons in CuInS2 single crystals

M. V. Yakushev, A. V. Mudryi, I. V. Victorov, J. Krustok, and E. Mellikov

Appl. Phys. Lett. 88, 011922 (2006); http://dx.doi.org/10.1063/1.2152114 (3 pages) | Cited 9 times

Online Publication Date: 6 January 2006

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High-quality single crystals of CuInS2, grown by the traveling heater method in an indium solvent, were characterized using photoluminescence (PL) and reflectance (RF) at temperatures from 4.2 to 300 K. A number of well-resolved sharp excitonic peaks have been observed in the near-band-edge region of the PL and RF spectra at 4.2 K. The lines at 1.536 and 1.554 eV in the RF spectra were associated with A and (B,C) free-excitonic transitions, respectively. In the PL spectra the A exciton revealed a well-resolved splitting into two peaks at 1.5348 and 1.5361 eV assigned to the lower and upper branches of exciton polariton, respectively. Other sharp lines were assigned to excitons bound at shallow impurities. The experimental temperature variation of the band gap was analyzed using the Bose–Einstein model. Two deeper bands in the PL spectra were identified as free-to-bound optical transitions followed by phonon replicas.
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71.35.-y Excitons and related phenomena
78.55.Hx Other solid inorganic materials
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
71.20.Nr Semiconductor compounds

Optical and structural changes of silver nanoparticles during photochromic transformation

C. Dahmen, A. N. Sprafke, H. Dieker, M. Wuttig, and G. von Plessen

Appl. Phys. Lett. 88, 011923 (2006); http://dx.doi.org/10.1063/1.2163268 (3 pages) | Cited 14 times

Online Publication Date: 6 January 2006

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Silver nanoparticles embedded in titanium oxide change their color upon irradiation with visible light. Here we investigate the origin of this photochromic effect. The color change is found to result chiefly from a reduction of the optical extinction peak of the photoexcited particle plasmons. From a comparison with x-ray diffraction experiments, we conclude that this reduction is caused by a photoinduced decrease of the mean size of the silver nanocrystals.
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81.07.Bc Nanocrystalline materials
42.70.−a
81.05.Bx Metals, semimetals, and alloys
81.15.Cd Deposition by sputtering
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
81.16.−c
61.46.−w
81.40.Gh Other heat and thermomechanical treatments
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
61.82.Rx Nanocrystalline materials
61.82.Bg Metals and alloys
78.68.+m Optical properties of surfaces
78.20.Jq Electro-optical effects
68.37.Lp Transmission electron microscopy (TEM)
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