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14 Jul 2003

Volume 83, Issue 2, pp. 207-403

Issue Cover Spotlight Figure

Appl. Phys. Lett. 83, 225 (2003); http://dx.doi.org/10.1063/1.1591241 (3 pages)

A. Borowiec, D. M. Bruce, Daniel T. Cassidy, and H. K. Haugen
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Analysis of transport properties of tetrahertz quantum cascade lasers

Hans Callebaut, Sushil Kumar, Benjamin S. Williams, Qing Hu, and John L. Reno

Appl. Phys. Lett. 83, 207 (2003); http://dx.doi.org/10.1063/1.1590749 (3 pages) | Cited 59 times

Online Publication Date: 8 July 2003

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We present a self-consistent modeling of a 3.4-THz intersubband laser device. An ensemble Monte Carlo simulation, including both carrier–carrier and carrier-phonon scattering, is used to predict current density, population inversion, gain, and electron temperature. However, these two scattering mechanisms alone appear to be insufficient to explain the observed current density. In addition, the insufficient scattering yields a gain that is slightly higher than inferred from experiments. This suggests the presence of a non-negligible scattering mechanism which is unaccounted for in the present calculations. © 2003 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
02.70.Uu Applications of Monte Carlo methods
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Short-wavelength intersubband absorption in strain compensated InGaAs/AlAs quantum well structures grown on InP

N. Georgiev, T. Dekorsy, F. Eichhorn, M. Helm, M. P. Semtsiv, and W. T. Masselink

Appl. Phys. Lett. 83, 210 (2003); http://dx.doi.org/10.1063/1.1592315 (3 pages) | Cited 10 times

Online Publication Date: 8 July 2003

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We have studied intersubband absorption in strain compensated InxGa1−xAs/AlAs/InyAl1−yAs multiple quantum wells and superlattices grown on InP. X-ray diffraction shows that the layers are pseudomorphically strained and exhibit slight compositional grading of the interfaces. Owing to the high AlAs barriers, the intersubband absorption can be tailored to wavelengths shorter than 2 μm. In some samples, a small, but non-negligible absorption is also observed with s-polarized light. © 2003 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.67.De Quantum wells
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
78.30.Fs III-V and II-VI semiconductors

Ultraintense light filaments transmitted through clouds

François Courvoisier, Véronique Boutou, Jérôme Kasparian, Estelle Salmon, Guillaume Méjean, Jin Yu, and Jean-Pierre Wolf

Appl. Phys. Lett. 83, 213 (2003); http://dx.doi.org/10.1063/1.1592615 (3 pages) | Cited 54 times

Online Publication Date: 8 July 2003

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We demonstrate that ultrashort and ultraintense light filaments survive their interaction with water droplets as large as 95 μm and that they are transmitted through water clouds having an optical thickness as high as 3.2 (transmission 5%). In contrast with linear optics, this remarkable transmission through optically dense media results from a dynamic energy balance between the quasisolitonic structure and the surrounding laser photon bath, which acts as an energy reservoir. Implications for free-space laser communications, remote sensing, and telemetry are discussed. © 2003 American Institute of Physics.
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42.68.Ge Effects of clouds and water; ice crystal phenomena
92.60.Nv Cloud physics and chemistry

Photonic bandpass filter for 1550 nm fabricated by femtosecond direct laser ablation

Ming Li, Kiyotaka Mori, Makoto Ishizuka, Xinbing Liu, Yoshimasa Sugimoto, Naoki Ikeda, and Kiyoshi Asakawa

Appl. Phys. Lett. 83, 216 (2003); http://dx.doi.org/10.1063/1.1592619 (3 pages) | Cited 8 times

Online Publication Date: 8 July 2003

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A bandpass filter, based on the one-dimensional photonic band-gap crystal concept, was fabricated using an ultrafast laser. As predicted by theory, a high-transmission window appeared in the band gap. The photonic crystal operates in the 1550 nm region. A high machining accuracy of ∼ 15 nm was achieved during our investigation, which is the key for the operability of the photonic device. © 2003 American Institute of Physics.
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42.79.Ci Filters, zone plates, and polarizers
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.70.Qs Photonic bandgap materials
42.82.Et Waveguides, couplers, and arrays
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.62.Cf Industrial applications

Radial distribution of attenuation in gamma-irradiated single-mode optical fibers

S. Girard, I. Trenteseaux, Y. Ouerdane, J.-P. Meunier, A. Boukenter, J.-L. Derep, and L. Thonnérieux

Appl. Phys. Lett. 83, 219 (2003); http://dx.doi.org/10.1063/1.1591250 (3 pages) | Cited 4 times

Online Publication Date: 8 July 2003

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In this letter, a method to determine the radial distribution of attenuation in single-mode optical fibers is proposed. This method is based on guided mode power and loss measurements for different fiber packaging. The most accurate radial attenuation distribution is calculated from experimental results. This approach allows localizing the absorbing or scattering defects along the radial cross section of fibers. As an example, a γ-irradiated germanosilicate fiber is studied at three different wavelengths. Through correlation with fiber chemical analysis, the contributions of each dopant to the permanent radiation-induced losses can be identified and quantified. At 980 nm, phosphorus-related color centers are the origin of induced losses, whereas for shorter wavelengths the influence of germanium-related color centers on fiber behavior becomes dominant. © 2003 American Institute of Physics.
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42.81.Dp Propagation, scattering, and losses; solitons
61.80.Ed γ-ray effects
61.82.Ms Insulators

Imaging of terahertz radiation using a Rydberg atom photocathode

A. Gürtler, A. S. Meijer, and W. J. van der Zande

Appl. Phys. Lett. 83, 222 (2003); http://dx.doi.org/10.1063/1.1591251 (3 pages) | Cited 4 times

Online Publication Date: 8 July 2003

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We report on a photocathode for far-infrared terahertz (THz) pulses based on ionization of gas-phase Rydberg atoms. We demonstrate the cathode by showing measurements of the beam profile of an unfocused THz beam in the far field of the emitter using an open ion optics and a contact print image of a spatial mask using THz pulse energies of less than 10 nJ. © 2003 American Institute of Physics.
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85.60.Ha Photomultipliers; phototubes and photocathodes
41.85.-p Beam optics

Imaging the strain fields resulting from laser micromachining of semiconductors

A. Borowiec, D. M. Bruce, Daniel T. Cassidy, and H. K. Haugen

Appl. Phys. Lett. 83, 225 (2003); http://dx.doi.org/10.1063/1.1591241 (3 pages) | Cited 17 times

Online Publication Date: 8 July 2003

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The residual strain fields resulting from laser micromachining of grooves in indium phosphide with femtosecond and nanosecond light pulses are analyzed using a spatially resolved degree-of-polarization photoluminescence technique. Significant differences in the geometry of the strain patterns are observed in grooves machined by femtosecond and nanosecond pulses. For the specific conditions investigated, the sign of the degree of polarization signal is opposite in the two cases indicating that areas under tension in femtosecond machined samples are under compression in nanosecond machined samples and visa versa. The experimental data are compared with results from a finite element model. © 2003 American Institute of Physics.
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81.20.Wk Machining, milling
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
81.05.Ea III-V semiconductors
07.10.Cm Micromechanical devices and systems
68.47.Fg Semiconductor surfaces
42.62.Cf Industrial applications
02.70.Dh Finite-element and Galerkin methods
78.55.Cr III-V semiconductors

Simultaneous cw red, yellow, and green light generation, “traffic signal lights,” by frequency doubling and sum-frequency mixing in an aperiodically poled LiTaO3

Jing-Liang He, Jun Liao, Hui Liu, Juan Du, Fei Xu, Hui-Tian Wang, S. N. Zhu, Y. Y. Zhu, and N. B. Ming

Appl. Phys. Lett. 83, 228 (2003); http://dx.doi.org/10.1063/1.1592635 (3 pages) | Cited 14 times

Online Publication Date: 8 July 2003

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We demonstrate simultaneously efficient generation of cw red, yellow, and green coherent radiations, “traffic signal lights,” by multifrequency conversions from a diode-pumped Nd:YVO4 dual-wavelength laser with a single-pass aperiodically poled LiTaO3. The 1.8 mW red at 671 nm and 0.64 mW green at 532 nm are, respectively, generated by frequency doubling of fundamental waves at 1342 and 1064 nm, and 0.79 mW yellow at 593 nm is produced by sum-frequency mixing of the two fundamental waves, under two fundamental waves of 970 mW at 1342 nm and 940 mW at 1064 nm. © 2003 American Institute of Physics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.72.Bj Visible and ultraviolet sources
42.55.Rz Doped-insulator lasers and other solid state lasers

Photonic crystal waveguides with multiple 90° bends

Young-Geun Roh, Sungjoon Yoon, Sunghwan Kim, Heonsu Jeon, Seung-Ho Han, Q-Han Park, and Inkyu Park

Appl. Phys. Lett. 83, 231 (2003); http://dx.doi.org/10.1063/1.1591080 (3 pages) | Cited 5 times

Online Publication Date: 8 July 2003

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In order to emphasize and demonstrate the importance of light confinement in the vertical direction, an otherwise ordinary two-dimensional photonic crystal waveguide structure operating at microwave frequencies was sandwiched between two metal plates. Such waveguides exhibited excellent guiding properties despite the existence of multiple 90° bends. From the experimental data, we have estimated that the propagation velocity of the waveguide is about 0.47 c, regardless of the number of bends, and that the bending loss is only 0.1 dB per bend. © 2003 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
42.65.Wi Nonlinear waveguides
42.79.Gn Optical waveguides and couplers

Optical activity in subwavelength-period arrays of chiral metallic particles

Tuomas Vallius, Konstantins Jefimovs, Jari Turunen, Pasi Vahimaa, and Yuri Svirko

Appl. Phys. Lett. 83, 234 (2003); http://dx.doi.org/10.1063/1.1592015 (3 pages) | Cited 37 times

Online Publication Date: 8 July 2003

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We report on a chirality-induced polarization effect in a planar subwavelength metallic nanograting. We demonstrate that the grating rotates the polarization at normal incidence. Because of the fourfold rotation symmetry, the effect does not depend on the incident beam polarization, but resembles optical activity in isotropic media. We use rigorous diffraction theory to show that polarization effects in the zeroth diffraction order take place in the presence of waveguide resonances with subwavelength-period arrays of chiral metallic particles. © 2003 American Institute of Physics.
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42.25.Ja Polarization
78.20.Ek Optical activity
42.25.Fx Diffraction and scattering
42.70.Qs Photonic bandgap materials

Tunable terahertz wave generation in the 3- to 7-THz region from GaP

T. Tanabe, K. Suto, J. Nishizawa, K. Saito, and T. Kimura

Appl. Phys. Lett. 83, 237 (2003); http://dx.doi.org/10.1063/1.1592889 (3 pages) | Cited 79 times

Online Publication Date: 8 July 2003

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Following the generation of tunable terahertz waves from GaP in the 0.5- to 3-THz region, we extended the frequency region up to 7 THz, using an optical parametric oscillator and a YAG laser (1.064 μm). The tuning angle θin increased superlinearly in the 3- to 7-THz region, so that the total reflection took place at 5 THz, which was avoided by rotating the crystal relative to the incident optic axis. As a result, terahertz output peak powers of 100 mW at up to 5.6 THz and 3 mW at 7 THz were obtained, at pump and signal energies of 3 mJ, respectively. © 2003 American Institute of Physics.
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07.57.Hm Infrared, submillimeter wave, microwave, and radiowave sources
78.70.Gq Microwave and radio-frequency interactions
42.65.Yj Optical parametric oscillators and amplifiers
84.40.-x Radiowave and microwave (including millimeter wave) technology
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Laser-induced plasmas in micromachined fused silica cavities

Xianzhong Zeng, Samuel S. Mao, Chunyi Liu, Xianglei Mao, Ralph Greif, and Richard E. Russo

Appl. Phys. Lett. 83, 240 (2003); http://dx.doi.org/10.1063/1.1591996 (3 pages) | Cited 11 times

Online Publication Date: 8 July 2003

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Cavity formation is a frequent result in many laser ablation applications. Although most theoretical investigations have been devoted to laser ablation on a flat surface, the development of a laser plasma inside a cavity is of both fundamental as well as practical significance. In this study, the temperature and electron number density of laser-induced plasmas in fused silica cavities were determined using spectroscopic methods. The effects of cavity aspect ratio on plasma properties were investigated. The temperature and electron number density of laser-induced plasma were measured to be much higher and to decrease faster for a plasma inside a cavity than on the flat surface. Cavity wall influences on the plasma expansion are discussed. © 2003 American Institute of Physics.
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52.38.Mf Laser ablation
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.25.-b Plasma properties
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
79.20.Ds Laser-beam impact phenomena

Ion flux nonuniformities in large-area high-frequency capacitive discharges

A. Perret, P. Chabert, J.-P. Booth, J. Jolly, J. Guillon, and Ph. Auvray

Appl. Phys. Lett. 83, 243 (2003); http://dx.doi.org/10.1063/1.1592617 (3 pages) | Cited 41 times

Online Publication Date: 8 July 2003

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Strong nonuniformities of plasma production are expected in capacitive discharges if the excitation wavelength becomes comparable to the reactor size (standing-wave effect) and/or if the plasma skin depth becomes comparable to the plate separation (skin effect) [M. A. Lieberman et al., Plasma Sources Sci. Technol. 11, 283 (2002)]. Ion flux uniformity measurements were carried out in a large-area square (40 cm×40 cm) capacitive discharge driven at frequencies between 13.56 MHz and 81.36 MHz in argon gas at 150 mTorr. At 13.56 MHz, the ion flux was uniform to ±5%. At 60 MHz (and above) and at low rf power, the standing-wave effect was seen (maximum of the ion flux at the center), in good quantitative agreement with theory. At higher rf power, maxima of the ion flux were observed at the edges, due either to the skin effect or to other edge effects. © 2003 American Institute of Physics.
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52.80.Pi High-frequency and RF discharges
52.50.-b Plasma production and heating
52.25.-b Plasma properties
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Reflective thermal lensing and optical measurement of thermal diffusivity in liquids

Daniel Comeau, Alain Haché, and Noureddine Melikechi

Appl. Phys. Lett. 83, 246 (2003); http://dx.doi.org/10.1063/1.1589199 (3 pages) | Cited 11 times

Online Publication Date: 8 July 2003

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Using a pump-probe laser technique, we analyze the relaxation dynamics of a thermal lens generated at the surface of metal films deposited on a glass substrate. When the film is in contact with a liquid and the film is periodically heated with an optical source, the dynamics of the thermal lens is found to be closely related to the thermal properties of its environment. As a result, reflective thermal lensing can be used to measure the thermal diffusivity of a variety of liquids placed in contact with the film to an accuracy better than 2%. Experimental results point to applications to the study of transient effects in fluids and immiscible liquids, and detection of trace of contaminants in solvents. © 2003 American Institute of Physics.
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07.20.-n Thermal instruments and apparatus
66.25.+g Thermal conduction in nonmetallic liquids
07.60.-j Optical instruments and equipment

Nanosecond time-resolved Raman spectroscopy on phase transition of polytetrafluoroethylene under laser-driven shock compression

H. Nagao, A. Matsuda, K. G. Nakamura, and K. Kondo

Appl. Phys. Lett. 83, 249 (2003); http://dx.doi.org/10.1063/1.1590742 (2 pages) | Cited 13 times

Online Publication Date: 8 July 2003

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Nanosecond time-resolved Raman spectroscopy is performed on polytetrafluoroethylene (PTFE) under laser shock compression at approximately 1 GPa. Blueshifts (8 cm−1) of a C–C stretching and redshifts (−8 cm−1) of a CF2 twisting in Raman spectrum due to a high-pressure phase (phase III) are observed. High-pressure phase transition to phase III of PTFE is suggested to occur within 10 ns. © 2003 American Institute of Physics.
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78.30.Jw Organic compounds, polymers
78.47.-p Spectroscopy of solid state dynamics
64.70.K- Solid-solid transitions
62.50.-p High-pressure effects in solids and liquids
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.Pv Polymers, organic compounds

Effects of film polarities on InN growth by molecular-beam epitaxy

K. Xu and A. Yoshikawa

Appl. Phys. Lett. 83, 251 (2003); http://dx.doi.org/10.1063/1.1592309 (3 pages) | Cited 95 times

Online Publication Date: 8 July 2003

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Effects of the film polarity on InN growth were investigated in molecular-beam epitaxy (MBE). It was found that N-polarity InN could be grown at higher temperatures than In-polarity one. For the In-polarity films, which were grown on Ga-polar GaN template, the highest growth temperature was limited below 500 °C, and the surface morphology and crystal quality tended to be poor mainly because of the tolerated low growth temperature. While for the N-polarity InN films, which were grown on MBE-grown N-polar GaN, the growth temperature could be as high as 600 °C. The step-flow-like growth morphology was achieved for the InN films grown with N polarity at 580 °C. The resulting full widths of half maximum of x-ray rocking curve around InN (002) and (102) reflections were about 200–250 and 950–1100 arc sec, respectively. The photoluminescence of the InN films peaked at 0.697 eV. The recording Hall mobility of InN film grown in N polarity is 1400 cm2/V s with a background carrier concentration of 1.56×1018 cm−3 at room temperature. For both-polarity films, we found N-rich condition was necessary for the stable InN growth. © 2003 American Institute of Physics.
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68.55.-a Thin film structure and morphology
73.61.Ey III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)

Optical properties of annealed CdTe self-assembled quantum dots

S. Mackowski, L. M. Smith, H. E. Jackson, W. Heiss, J. Kossut, and G. Karczewski

Appl. Phys. Lett. 83, 254 (2003); http://dx.doi.org/10.1063/1.1591239 (3 pages) | Cited 19 times

Online Publication Date: 8 July 2003

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We report on the influence of postgrowth thermal annealing on the optical properties of CdTe/ZnTe self-assembled quantum dots (SAQDs). Ultrasharp emission lines in the micro-photoluminescence spectra demonstrate the continued presence of quantum dots (QDs) after annealing. Upon annealing, the emission from CdTe QDs shifts toward higher energies with a narrowing of the photoluminescence line of QDs ensemble. In addition, the decay time of the excitonic recombination decreases from 300 ps to 200 ps. These results indicate that interdiffusion of Zn and Cd into and out of the QDs leads to an increase of the average dot size and simultaneously a decrease in the confining potentials of the QD. The absence of a wetting layer makes the II–VI CdTe SAQDs much more sensitive to the thermal treatment than the III–V InAs-based dots. © 2003 American Institute of Physics.
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78.67.Hc Quantum dots
68.65.Hb Quantum dots (patterned in quantum wells)
61.72.Cc Kinetics of defect formation and annealing
73.21.La Quantum dots
78.55.Et II-VI semiconductors
71.35.Lk Collective effects (Bose effects, phase space filling, and excitonic phase transitions)
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Shape memory effect in nanoindentation of nickel–titanium thin films

G. A. Shaw, D. S. Stone, A. D. Johnson, A. B. Ellis, and W. C. Crone

Appl. Phys. Lett. 83, 257 (2003); http://dx.doi.org/10.1063/1.1591235 (3 pages) | Cited 18 times

Online Publication Date: 8 July 2003

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In this study, a series of nanoindentations was made on NiTi shape memory alloy thin films at millinewton loads with a Berkovich indenter. Mapping of the indentation topography using atomic force microscopy reveals direct evidence that the thermally induced martensitic transformation of these films allows for partial indent recovery on the nanoscale. Indeed, recovery is nearly complete at indentation depths of less than 100 nm. A hemispherical cavity model is presented to predict an upper limit to shape memory recovery of sharp indentations. © 2003 American Institute of Physics.
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68.60.Bs Mechanical and acoustical properties
62.20.Qp Friction, tribology, and hardness
62.20.F- Deformation and plasticity
81.30.Kf Martensitic transformations
64.70.K- Solid-solid transitions
81.40.Lm Deformation, plasticity, and creep
68.37.Ps Atomic force microscopy (AFM)
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure

Three-beam interference method for measuring very thin films

I. Leizerson and S. G. Lipson

Appl. Phys. Lett. 83, 260 (2003); http://dx.doi.org/10.1063/1.1591234 (3 pages) | Cited 5 times

Online Publication Date: 8 July 2003

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We present an experimental method which allows the real time measurement of the thickness of a thin film on a transparent substrate in an imaging mode. Imaging ellipsometry cannot be used for such problems because of reflections from the backsurface of the substrate. Its application to the measurement of water films down to 30 Å on mica is described. The sensitivity is found to be comparable to that of imaging ellipsometry. We investigate the relationship between thickness resolution and spatial resolution and give an optional modification of the method which can be applied to opaque substrates. © 2003 American Institute of Physics.
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68.15.+e Liquid thin films
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)

Resonant optical nonlinearities from intersubband transitions in GaN/AlN quantum wells

R. Rapaport, Gang Chen, O. Mitrofanov, C. Gmachl, H. M. Ng, and S. N. G. Chu

Appl. Phys. Lett. 83, 263 (2003); http://dx.doi.org/10.1063/1.1591247 (3 pages) | Cited 19 times

Online Publication Date: 8 July 2003

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We measured the resonant nonlinear optical response of the intersubband transitions in GaN/AlGaN multiple quantum well structures. The measured value for the nonlinear susceptibility is found to be much smaller than previous theoretical predictions. This is attributed to a large electron dephasing due to material imperfections. We show that at higher incident intensities, absorption saturation is possible, and measure the saturation intensity for various wavelengths around the transition resonance. We also discuss the prospects of using such structures as building blocks for all-optical nonlinear switches, in light of our experimental findings. © 2003 American Institute of Physics.
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42.65.An Optical susceptibility, hyperpolarizability
78.67.De Quantum wells
42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.50.Gy Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption

Long-lasting photoluminescence in freestanding GaN templates

M. A. Reshchikov, M. Zafar Iqbal, H. Morkoç, S. S. Park, and K. Y. Lee

Appl. Phys. Lett. 83, 266 (2003); http://dx.doi.org/10.1063/1.1589194 (3 pages) | Cited 6 times

Online Publication Date: 8 July 2003

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We studied time-resolved photoluminescence (PL) over a temporal range 10−6–103 s in high-purity freestanding GaN templates. Red, yellow, green, blue, and shallow donor–acceptor emission bands can be resolved in the PL spectrum. Observation of luminescence long after the excitation is switched off is a striking feature of our study. The persistent PL observed for all above bands, except for the green band, is primarily attributed to the donor–acceptor-pair-type recombination. An unusually slow, nonexponential decay of radiative transitions from the conduction band to the shallow acceptor was also observed, pointing to some additional mechanism for the persistent PL. Possible role of the surface states in this effect is discussed. © 2003 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.47.-p Spectroscopy of solid state dynamics

Correlation between the ordered structure and the valence-band splitting in highly strained CdxZn1−xTe epilayers

T. W. Kim, K. D. Kwack, J. G. Park, H. S. Lee, J. Y. Lee, M. S. Jang, and H. L. Park

Appl. Phys. Lett. 83, 269 (2003); http://dx.doi.org/10.1063/1.1592622 (3 pages) | Cited 3 times

Online Publication Date: 8 July 2003

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Selected-area electron diffraction pattern (SADP) results showed two sets of {1/2 1/2 1/2} superstructure reflections with symmetrical intensities along the [110] axis, and the corresponding high-resolution transmission electron microscopy images indicated a doublet periodicity in the contrast of the {111} lattice planes. Photoluminescence spectra from highly strained CdxZn1−xTe/GaAs heterostructures showed that the valence-band splitting into the heavy hole and the light hole bands occurred as the Cd mole fraction was increased. The valence-band splitting is strongly correlated to the CuPtB-type ordered structure in highly strained heterostructures. © 2003 American Institute of Physics.
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73.20.At Surface states, band structure, electron density of states
78.66.Hf II-VI semiconductors
78.55.Et II-VI semiconductors
68.55.-a Thin film structure and morphology

Strong photoluminescence and cathodoluminescence due to f–f transitions in Eu3+ doped Al2O3 powders prepared by direct combustion synthesis and thin films deposited by laser ablation

Nikifor Rakov, Francisco E. Ramos, Gustavo Hirata, and Mufei Xiao

Appl. Phys. Lett. 83, 272 (2003); http://dx.doi.org/10.1063/1.1592636 (3 pages) | Cited 35 times

Online Publication Date: 8 July 2003

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In this letter, we report on fabrication and luminescent properties of phosphor powders and thin films of Eu3+ doped alumina Al2O3. The powders were fabricated by combustion synthesis process at a low temperature, 280 °C and showed strong photoluminescent and cathodoluminescent emissions. Powders of Eu3+ doped Al2O3 of concentration 1.0 mol % were deposited on quartz-glass substrates to form thin films by means of laser ablation. Under ultraviolet excitation and electron beam excitation, these samples containing microcrystalline structures showed strong luminescence due to f–f transitions, and the dominant transition was the hypersensitive 5D0→7F2 red emission of Eu3+. © 2003 American Institute of Physics.
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78.55.Hx Other solid inorganic materials
78.60.Hk Cathodoluminescence, ionoluminescence
78.66.Nk Insulators
81.05.Cy Elemental semiconductors
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
81.15.Fg Pulsed laser ablation deposition

Stacking-fault-induced intermediate structure in bismuth titanate

Y. Yoneda, J. Mizuki, R. Katayama, K. Yagi, H. Terauchi, S. Hamazaki, and M. Takashige

Appl. Phys. Lett. 83, 275 (2003); http://dx.doi.org/10.1063/1.1592000 (3 pages) | Cited 9 times

Online Publication Date: 8 July 2003

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We observed an intermediate structure during the recrystallization process from the amorphous state of Bi4Ti3O12 prepared by rapid quenching. The intermediate structure which appears during the recrystallization process consists of two phases; one is pyrochlore Bi2Ti2O7 phase and the other is a stacking-fault-induced structure under the excessive Bi condition. The microstructure of the stacking-fault-induced structure was investigated by synchrotron x-ray diffraction. In the case of a large number of Bi2O2, some are inserted between the pseudoperovskite layers of Bi4Ti3O12, and a nonstoichiometric Bi2WO6-like structure is stabilized. © 2003 American Institute of Physics.
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61.66.Fn Inorganic compounds
61.72.Nn Stacking faults and other planar or extended defects
77.80.-e Ferroelectricity and antiferroelectricity
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
81.10.Jt Growth from solid phases (including multiphase diffusion and recrystallization)

Optical properties and electronic structure of rock-salt ZnO under pressure

A. Segura, J. A. Sans, F. J. Manjón, A. Muñoz, and M. J. Herrera-Cabrera

Appl. Phys. Lett. 83, 278 (2003); http://dx.doi.org/10.1063/1.1591995 (3 pages) | Cited 49 times

Online Publication Date: 8 July 2003

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Show Abstract
This letter reports on the pressure dependence of the optical absorption edge of ZnO in the rock-salt phase, up to 20 GPa. Both vapor-phase monocrystals and pulsed-laser-deposition thin films on mica have been investigated. Rock-salt ZnO is shown to be an indirect semiconductor with a band gap of 2.45±0.15 eV, whose pressure coefficient is very small. At higher photon energies, a direct transition is observed (4.6 eV at 10 GPa), with a positive pressure coefficient (around 40±3 meV/GPa between 5 and 19 GPa). These results are interpreted on the basis of first-principles electronic band structure calculations. © 2003 American Institute of Physics.
Show PACS
78.40.Fy Semiconductors
78.66.Hf II-VI semiconductors
81.15.Fg Pulsed laser ablation deposition
71.20.Nr Semiconductor compounds
62.50.-p High-pressure effects in solids and liquids
71.15.-m Methods of electronic structure calculations
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