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11 Sep 2000

Volume 77, Issue 11, pp. 1569-1731

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Crucial role of metal surface in enhanced transmission through subwavelength apertures

D. E. Grupp, H. J. Lezec, T. W. Ebbesen, K. M. Pellerin, and Tineke Thio

Appl. Phys. Lett. 77, 1569 (2000); http://dx.doi.org/10.1063/1.1308530 (3 pages) | Cited 149 times

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In order to understand the details of the extraordinary enhancement of the optical transmission through subwavelength holes in metal films, we have fabricated perforated free-standing metal films where the nature of the bulk and surfaces can be controlled independently. We find that the transmission enhancement depends only on the dielectric properties of the metal within a skin depth of the two in-plane surfaces and not on those of the film core, nor on the metal constituting the hole walls. This provides direct and conclusive evidence that the phenomenon is mediated by surface plasmons. © 2000 American Institute of Physics.
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78.66.Bz Metals and metallic alloys
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
78.40.Kc Metals, semimetals, and alloys
78.30.Er Solid metals and alloys

Very long wavelength infrared type-II detectors operating at 80 K

H. Mohseni, A. Tahraoui, J. Wojkowski, M. Razeghi, G. J. Brown, W. C. Mitchel, and Y. S. Park

Appl. Phys. Lett. 77, 1572 (2000); http://dx.doi.org/10.1063/1.1308528 (3 pages) | Cited 24 times

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We report a demonstration of very long wavelength infrared detectors based on InAs/GaSb superlattices operating at T = 80 K. Detector structures with excellent material quality were grown on an optimized GaSb buffer layer on GaAs semi-insulating substrates. Photoconductive devices with 50% cutoff wavelength of λc = 17 μm showed a peak responsivity of about 100 mA/W at T = 80 K. Devices with 50% cutoff wavelengths up to λc = 22 μm were demonstrated at this temperature. Good uniformity was obtained over large areas even for the devices with very long cutoff wavelengths. © 2000 American Institute of Physics.
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07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.60.Gz Photodetectors (including infrared and CCD detectors)
72.40.+w Photoconduction and photovoltaic effects
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
73.61.Ey III-V semiconductors

Sharp green electroluminescence from 1H-pyrazolo[3,4-b]quinoline-based light-emitting diodes

Y. T. Tao, E. Balasubramaniam, A. Danel, B. Jarosz, and P. Tomasik

Appl. Phys. Lett. 77, 1575 (2000); http://dx.doi.org/10.1063/1.1309016 (3 pages) | Cited 29 times

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A multilayer organic light-emitting diode was fabricated using a fluorescent compound {6-N,N-diethylamino-1-methyl-3-phenyl-1H-pyrazolo[3,4-b]quinoline} (PAQ–NEt2) doped into the hole-transporting layer of NPB {4,4′-bis[N-(1-naphthyl-1-)-N-phenyl-amino]-biphenyl}, with the TPBI {2,2′,2″-(1,3,5-phenylene)tris[1-phenyl-1H-benzimidazole]} as an electrontransporting material. At 16% PAQ–NEt2 doping concentration, the device gave a sharp, bright, and efficient green electroluminescence (EL) peaked at around 530 nm. The full width at half maximum of the EL is 60 nm, which is 60% of the green emission from typical NPB/AlQ [where AlQ=tris(8-hydroxyquinoline) aluminum] device. For the same concentration, a maximum luminance of 37 000 cd/m2 was obtained at 10.0 V and the maximum power, luminescence, and external quantum efficiencies were obtained 4.2 lm/W, 6.0 cd/A, and 1.6%, respectively, at 5.0 V. © 2000 American Institute of Physics.
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78.60.Fi Electroluminescence
85.60.Jb Light-emitting devices
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
78.66.Qn Polymers; organic compounds

Effect of electric field on one-quantum photodecay of oxygen-deficient centers in germanosilicate fibers

A. O. Rybaltovskii, Yu. S. Zavorotny, P. V. Chernov, V. N. Bagratashvili, S. I. Tsypina, and P. G. Kazansky

Appl. Phys. Lett. 77, 1578 (2000); http://dx.doi.org/10.1063/1.1308536 (3 pages) | Cited 2 times

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The effect of a strong electric field (up to 106 V/cm) on one-quantum UV photoexcitation and photodecomposition of germanium oxygen deficient centers (GODC) in twin-hole germanosilicate fibers with internal wire electrodes is reported. The fiber has been irradiated with the UV light of a deuterium lamp and triplet photoluminescence of GODC has been used to monitor the kinetics of its photodecay. Applying such an electric field did not affect the spectral characteristics of GODC but increased the rate of their one-quantum photodecomposition, while direct photoionization and charge separation did not take place. We have also shown that this effect is caused by the suppression of secondary photoinduced recombination processes of intermediates, rather than by acceleration of primary photodecomposition of GODC. © 2000 American Institute of Physics.
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78.55.Hx Other solid inorganic materials
81.05.Kf Glasses (including metallic glasses)
78.47.-p Spectroscopy of solid state dynamics
82.50.Bc Processes caused by infrared radiation
82.50.Hp Processes caused by visible and UV light
61.43.Fs Glasses
78.66.Jg Amorphous semiconductors; glasses
71.55.Jv Disordered structures; amorphous and glassy solids
78.20.Jq Electro-optical effects

Room-temperature low-threshold low-loss continuous-wave operation of 2.26 μm GaInAsSb/AlGaAsSb quantum-well laser diodes

C. Mermelstein, S. Simanowski, M. Mayer, R. Kiefer, J. Schmitz, M. Walther, and J. Wagner

Appl. Phys. Lett. 77, 1581 (2000); http://dx.doi.org/10.1063/1.1308537 (3 pages) | Cited 23 times

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Strained single- and triple-quantum-well (SQW and TQW), large optical cavity GaInAsSb/AlGaAsSb/GaSb laser diodes emitting at 2.26 μm are investigated. Internal loss coefficients as low as 5 and 7.7 cm−1 for the SQW and TQW, respectively, and relatively high internal quantum efficiencies of 65% (SQW) and 69% (TQW) were obtained. Extrapolated threshold current densities for infinite cavity lengths of 55 and 150 A/cm2 have been deduced for the SQW and TQW, respectively. These values scale very well with the number of QWs and are among the lowest reported for diode lasers in this wavelength range. A differential quantum efficiency as high as 50% and a total power efficiency of 23% were achieved at 280 K. The temperature dependence of the threshold current density revealed a high characteristic temperature of 110 K. Single-ended output powers of 240 mW in continuous-wave mode and exceeding 0.5 W in pulsed operation were obtained for a TQW laser with high-reflection/antireflection coated facets at 280 K, mounted substrate-side down. © 2000 American Institute of Physics.
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42.60.By Design of specific laser systems
42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.79.Wc Optical coatings

Direct observation of lasing mode in a microdisk laser by a near-field-probing technique

Toshihiko Baba, Hiroshi Yamada, and Atsushi Sakai

Appl. Phys. Lett. 77, 1584 (2000); http://dx.doi.org/10.1063/1.1308539 (3 pages) | Cited 6 times

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Evanescent field profiles of whispering gallery (WG) modes in a 1.6-μm-GaInAsP microdisk injection laser were investigated by scanning a nanoprobe near the periphery of a lasing microdisk. The increase in threshold current due to the light scattering by the probe and the corresponding decrease in laser light were observed experimentally. Two-dimensional images of the evanescent field, which agreed well with theoretical expectations, were obtained by the use of a Pt–Ir probe. The images indicate that the WG mode is strongly locked by the fourfold symmetry in the microdisk with center post claddings. This characteristic is favorable for the microdisk laser itself to be used as an active near-field probe. A lower contrast image obtained by the use of a tapered silica fiber probe suggests that the microdisk probe can be sensitive to both surface profiles and optical properties of the object. © 2000 American Institute of Physics.
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42.55.Sa Microcavity and microdisk lasers
81.05.Ea III-V semiconductors
07.79.Fc Near-field scanning optical microscopes
78.66.Fd III-V semiconductors

Emission behavior of molecularly doped electroluminescent device using liquid-crystalline matrix

Hiroyuki Mochizuki, Takahiro Hasui, Takeshi Shiono, Tomiki Ikeda, Chihaya Adachi, Yoshio Taniguchi, and Yasuhiko Shirota

Appl. Phys. Lett. 77, 1587 (2000); http://dx.doi.org/10.1063/1.1309026 (3 pages) | Cited 7 times

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Electroluminescent (EL) behavior has been evaluated in a cell which contained molecular dispersion of 1,4-bis(N,N-diphenylaminophenyl-1,3,4-oxadiazolyl)benzene (OXD) in a low-molecularweight liquid crystal, 4-octyloxy-4′-cyanobiphenyl (8OCB). EL emission was observed above the temperature where the OXD/8OCB mixture showed a liquid-crystalline phase. Furthermore, we fabricated an EL device which consisted of interdigital electrodes coated onto a glass substrate. It was found that the EL emission from the device was highly polarized. © 2000 American Institute of Physics.
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78.60.Fi Electroluminescence
42.79.Kr Display devices, liquid-crystal devices
85.60.Pg Display systems
78.66.Qn Polymers; organic compounds

Impact of in-plane anisotropic strain on the polarization behavior of vertical-cavity surface-emitting lasers

K. Panajotov, B. Nagler, G. Verschaffelt, A. Georgievski, H. Thienpont, J. Danckaert, and I. Veretennicoff

Appl. Phys. Lett. 77, 1590 (2000); http://dx.doi.org/10.1063/1.1309019 (3 pages) | Cited 41 times

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We experimentally demonstrate that the presence of switching between two fundamental modes with orthogonal linear polarization in vertical-cavity surface-emitting lasers and the current at which this phenomenon occurs depend on both the magnitude and the orientation of an externally induced in-plane anisotropic strain. We interpret this behavior by considering the anisotropy in gain and in refractive index, both induced by the in-plane strain, and by accounting for a redshift of the two gain curves as a result of current-induced heating. © 2000 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Magneto-optical mode conversion in Cd1−xMnxTe waveguide on GaAs substrate

W. Zaets and K. Ando

Appl. Phys. Lett. 77, 1593 (2000); http://dx.doi.org/10.1063/1.1310176 (3 pages) | Cited 27 times

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Magneto-optical mode conversion was achieved in a waveguide of diluted magnetic semiconductor Cd1−xMnxTe grown on GaAs substrate. Mode conversion ratio up to 34% under a magnetic field of 5.5 kG was obtained. Cd1−xMnxTe waveguide showed low optical loss, 4 dB/cm, and high magneto-optical figure-of-merit, 15 deg/dB/kG at λ = 790 nm. This result shows the feasibility of monolithical integration of an optical isolator with semiconductor optoelectronic devices. © 2000 American Institute of Physics.
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78.66.Hf II-VI semiconductors
78.20.Ls Magneto-optical effects
85.70.Sq Magnetooptical devices
42.82.Et Waveguides, couplers, and arrays
75.50.Pp Magnetic semiconductors
68.55.-a Thin film structure and morphology
42.79.Gn Optical waveguides and couplers

Very narrow spectral filters with multilayered grating-waveguide structures

Guy Levy-Yurista and Asher A. Friesem

Appl. Phys. Lett. 77, 1596 (2000); http://dx.doi.org/10.1063/1.1310172 (3 pages) | Cited 26 times

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Promising configurations for grating-waveguide structures are presented. In these structures, the grating layer, which is normally adjacent to the waveguide layer, is displaced by means of an intermediate layer, resulting in significant reduction of losses and weaker coupling. This leads to very narrow spectral bandwidths and high contrast ratios. Experimental results reveal that the spectral bandwidths can be as low as 0.1 nm with contrast ratios greater than 1000, suggesting that these grating-waveguide structures could be useful for optical communication networks. © 2000 American Institute of Physics.
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42.79.Ci Filters, zone plates, and polarizers
42.79.Dj Gratings
42.79.Gn Optical waveguides and couplers
42.82.Et Waveguides, couplers, and arrays

The role of the molecular dynamics in the local intensity instabilities of large aperture dye lasers

I. Leyva and J. M. Guerra

Appl. Phys. Lett. 77, 1599 (2000); http://dx.doi.org/10.1063/1.1310204 (3 pages) | Cited 1 time

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We study experimentally the influence of the molecular dynamics in the local intensity fluctuations of large aperture dye lasers, and find dependencies on solvent viscosity and active molecular size. This is an example of the complexity of the still quite unknown nonlinear processes that underlie the pattern formation dynamics in large aperture optical systems, in which the diffraction has lost influence and the bulk dynamics dominate. © 2000 American Institute of Physics.
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42.55.Mv Dye lasers

Integration of thin-film vertical-cavity surface-emitting lasers on AlN substrates using a functional layer transfer technique

Toshihiko Ouchi, Takahiro Sato, Hajime Sakata, and Yuichi Handa

Appl. Phys. Lett. 77, 1602 (2000); http://dx.doi.org/10.1063/1.1310205 (3 pages) | Cited 1 time

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We have demonstrated thin-film vertical-cavity surface-emitting lasers (VCSELs) on a selected substrate for the hybrid integration of optoelectronic devices. After fabricating VCSEL structures, the epitaxial side of the VCSEL wafer was bonded onto an AlN substrate using Au–Sn solder, and then the growth substrate of the wafer was removed. The devices fabricated by this technique exhibited threshold currents as low as VCSELs on the original growth substrate. The effective thermal resistance did not increase even after the growth substrate was removed. © 2000 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
85.60.-q Optoelectronic devices

Polarization modulation technique for magneto-optical quantitative vector magnetometry

P. Vavassori

Appl. Phys. Lett. 77, 1605 (2000); http://dx.doi.org/10.1063/1.1310169 (3 pages) | Cited 44 times

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This letter presents a method for determining the orientation of the magnetization vector during the reversal process in ferromagnetic films using a conventional setup for magneto-optical ellipsometry based on the photoelastic modulation technique for the modulation of polarization. The orientation is obtained through the determination of three orthogonal reduced (i.e., normalized to saturation value) magnetization components as a function of the external field. Test measurements on a reference sample are also presented, which confirm the reliability of the measurements and show what kind of information can be retrieved. © 2000 American Institute of Physics.
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75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
78.20.Ls Magneto-optical effects
07.55.Ge Magnetometers for magnetic field measurements

Reliability of photopumped AlxGa1−xAs–GaAs quantum well heterostructure lasers with top and bottom distributed native-oxide reflectors

D. A. Kellogg, N. Holonyak, and R. D. Dupuis

Appl. Phys. Lett. 77, 1608 (2000); http://dx.doi.org/10.1063/1.1310168 (3 pages) | Cited 2 times

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Data on an AlxGa1−xAs–GaAs quantum well heterostructure (QWH) designed to be oxidized and used as a photopumped vertical cavity surface emitting laser (VCSEL) are presented showing the full range in reliability (5+ years) from atmospheric decay of the as-grown crystal by hydrolyzation to protection of the QWH VCSEL by means of the Al-based native oxide (“wet” oxidation, 425 °C). In contrast to fully oxidized crystals in a VCSEL configuration that remain stable (AlAs layers converted to oxide), broad area p-n diodes made from the as-grown crystal, with buried AlAs layers exposed at edges, hydrolyze. © 2000 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Different types of chaos in an optically injected semiconductor laser

Bernd Krauskopf, Sebastian Wieczorek, and Daan Lenstra

Appl. Phys. Lett. 77, 1611 (2000); http://dx.doi.org/10.1063/1.1310213 (3 pages) | Cited 16 times

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With advanced tools from bifurcation theory routes to chaos via period doubling and the break-up of tori are identified. This allows us to distinguish between different types of chaos in terms of the output characteristics of the laser. We also find locking to a periodic solution inside a region of chaos. This information is important for applications requiring chaotic signals, such as encryption schemes. © 2000 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
05.45.-a Nonlinear dynamics and chaos
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Temperature dependence of the thermo-optic coefficient of InP, GaAs, and SiC from room temperature to 600 K at the wavelength of 1.5 μm

Francesco G. Della Corte, Giuseppe Cocorullo, Mario Iodice, and Ivo Rendina

Appl. Phys. Lett. 77, 1614 (2000); http://dx.doi.org/10.1063/1.1308529 (3 pages) | Cited 31 times

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The thermo-optic coefficient ∂n/∂T has been measured from room temperature to 600 K at the wavelength of 1523 nm in three important semiconductors for fiber-optic device fabrication, namely, InP, GaAs, and 6H–SiC. The adopted technique is very simple and is based on the observation of the periodicity of the signal transmitted, at the desired wavelength, by an étalon made of the material under test, when it experiences a temperature variation. The values of ∂n/∂T measured in InP and GaAs at room temperature are in agreement with previously reported ones, but increase with temperature with a weak quadratic dependence. SiC conversely shows a lower thermo-optic coefficient (2.77×10−5 K−1) at 300 K, which, however, doubles for a 300 K temperature increase. © 2000 American Institute of Physics.
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78.20.N- Thermo-optic effects
78.20.nb Photothermal effects
81.05.Ea III-V semiconductors

Effect of size and roughness on light transmission in a Si/SiO2 waveguide: Experiments and model

Kevin K. Lee, Desmond R. Lim, Hsin-Chiao Luan, Anuradha Agarwal, James Foresi, and Lionel C. Kimerling

Appl. Phys. Lett. 77, 1617 (2000); http://dx.doi.org/10.1063/1.1308532 (3 pages) | Cited 140 times

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In this letter, we experimentally evaluate the effect of miniaturization and surface roughness on transmission losses within a Si/SiO2 waveguide system, and explain the results using a theoretical model. Micrometer/nanometer-sized waveguides are imperative for its potential use in dense integrated optics and optical interconnection for silicon integrated circuits. A theoretical model was employed to predict the relationship between the transmission losses of the dielectric silicon waveguide and its width. This model accurately predicts that loss increases as waveguide width decreases. Furthermore, we show that a major source of loss comes from sidewall roughness. We have constructed a complete contour map showing the interdependence of sidewall roughness and transmission loss, to assist users in their design of an optimal waveguide fabrication process that minimizes loss. Additionally, users can find an effective path to reduce the scattering loss from sidewall roughness. Using this map, we confirm that nanometer-size silicon waveguides with 0.1 dB/cm transmission loss are possible with the currently available technology. © 2000 American Institute of Physics.
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42.82.Et Waveguides, couplers, and arrays
42.82.Bq Design and performance testing of integrated-optical systems
85.60.Bt Optoelectronic device characterization, design, and modeling
42.79.Gn Optical waveguides and couplers

Selective growth of nanocrystalline Si dots using an ultrathin-Si-oxide/oxynitride mask

Noriyuki Miyata, Heiji Watanabe, and Masakazu Ichikawa

Appl. Phys. Lett. 77, 1620 (2000); http://dx.doi.org/10.1063/1.1308523 (3 pages) | Cited 2 times

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We demonstrate the selective growth of nanocrystalline Si (nc–Si) dots by using ultrathin-Si-oxide/oxynitride mask and low-pressure chemical vapor deposition. The oxynitride layer is selectively grown on the Si(001)–2×1 open window formed in the ultrathin oxide layer by electron-beam-induced selective thermal decomposition. The 10-nm-scale hemispherical nc–Si dots grow selectively on the oxynitride-covered window within the incubation period in which Si growth does not occur on the oxide-covered surface. © 2000 American Institute of Physics.
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81.05.Cy Elemental semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.07.-b Nanoscale materials and structures: fabrication and characterization

Dome-to-pyramid shape transition in Ge/Si islands due to strain relaxation by interdiffusion

William L. Henstrom, Chuan-Pu Liu, J. Murray Gibson, T. I. Kamins, and R. Stanley Williams

Appl. Phys. Lett. 77, 1623 (2000); http://dx.doi.org/10.1063/1.1309027 (3 pages) | Cited 25 times

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Ge islands were grown on Si(001) and then annealed at 650 °C for 0, 20, 40, and 60 min in a chemical-vapor deposition reactor following Ge deposition. This letter confirms the previous observations directly. By combining the ability to quantify strain with the ability to measure island dimensions in a transmission electron microscope, we were able to plot strain versus aspect ratio for the various annealing times. The islands first relax strain because of Si intermixing with the Ge epilayer causes the lattice mismatch to be lowered. Once the mismatch is sufficiently reduced, and thus the strain energy sufficiently reduced, it becomes favorable for the islands to reverse their shape back from domes to pyramids, thus reducing surface energy. This confirms the reversibility of island shape and thus the thermodynamics of the transition. © 2000 American Institute of Physics.
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68.55.-a Thin film structure and morphology
68.60.Bs Mechanical and acoustical properties
68.35.Rh Phase transitions and critical phenomena
66.30.Ny Chemical interdiffusion; diffusion barriers
61.72.Cc Kinetics of defect formation and annealing
68.35.Md Surface thermodynamics, surface energies
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances

Layer-by-layer growth of GaN induced by silicon

A. Munkholm, Carol Thompson, M. V. Ramana Murty, J. A. Eastman, O. Auciello, G. B. Stephenson, P. Fini, S. P. DenBaars, and J. S. Speck

Appl. Phys. Lett. 77, 1626 (2000); http://dx.doi.org/10.1063/1.1309023 (3 pages) | Cited 19 times

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We present in situ x-ray scattering studies of surface morphology evolution during metal–organic chemical vapor deposition of GaN. Dosing the GaN(0001) surface with Si is shown to change the growth mode from step-flow to layer-by-layer over a wide temperature range. Annealing of highly doped layers causes Si to segregate to the surface, which also induces layer-by-layer growth. © 2000 American Institute of Physics.
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81.05.Ea III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.-a Thin film structure and morphology
68.35.B- Structure of clean surfaces (and surface reconstruction)
78.70.Ck X-ray scattering
61.72.Cc Kinetics of defect formation and annealing
64.75.-g Phase equilibria

Microstructural evolution of laser-exposed silicon targets in SF6 atmospheres

J. D. Fowlkes, A. J. Pedraza, and D. H. Lowndes

Appl. Phys. Lett. 77, 1629 (2000); http://dx.doi.org/10.1063/1.1308538 (3 pages) | Cited 21 times

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The microstructures formed at the surface of silicon during pulsed-laser irradiation in SF6-rich atmospheres consist of an array of microholes surrounded by microcones. It is shown that there is a dynamic interplay between the formation of microholes and microcones. Fluorine produced by the laser-induced decomposition of SF6 is most likely responsible for the etching/ablation process. It is proposed that silicon-rich molecules and clusters that form in and are ejected from the continually deepening microholes sustain the axial and lateral growth of the microcones. The laser-melted layer at the tip and sides of the cones efficiently collects the silicon-rich products formed upon ablation. The total and partial pressures of SF6 in the chamber play a major role in cone development, a clear indication that it is the laser-generated plasma that controls the growth of these cones. © 2000 American Institute of Physics.
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81.65.-b Surface treatments
81.05.Cy Elemental semiconductors
79.20.Ds Laser-beam impact phenomena
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.Fk Semiconductors
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
68.35.B- Structure of clean surfaces (and surface reconstruction)

Radiative and nonradiative recombination processes in lattice-matched (Cd,Zn)O/(Mg,Zn)O multiquantum wells

T. Makino, C. H. Chia, Nguen T. Tuan, Y. Segawa, M. Kawasaki, A. Ohtomo, K. Tamura, and H. Koinuma

Appl. Phys. Lett. 77, 1632 (2000); http://dx.doi.org/10.1063/1.1308540 (3 pages) | Cited 56 times

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Time-resolved photoluminescence studies have been performed on (Cd,Zn)O/(Mg,Zn)O multiquantum wells, which are almost perfectly lattice matched (0.034%), grown by laser molecular-beam epitaxy on a ScAlMgO4 substrate. Radiative recombination of excitons in the wells exhibits a significant spectral distribution of times. This distribution was interpreted in terms of localization of excitons by potential fluctuations due to alloy disorder and to well width and depth variations. The temperature dependence of the radiative lifetime of excitons was deduced from the measurement of both the photoluminescence decay time and intensity. We found that the radiative lifetime increases linearly with temperature, showing a two-dimensional feature of excitons in the quantum wells. © 2000 American Institute of Physics.
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78.55.Et II-VI semiconductors
81.05.Dz II-VI semiconductors
78.47.-p Spectroscopy of solid state dynamics
78.66.Hf II-VI semiconductors
73.61.Ga II-VI semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
71.35.-y Excitons and related phenomena
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Size control of erbium-doped silicon nanocrystals

John St. John, Jeffery L. Coffer, Yandong Chen, and Russell F. Pinizzotto

Appl. Phys. Lett. 77, 1635 (2000); http://dx.doi.org/10.1063/1.1309022 (3 pages) | Cited 11 times

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This work describes the effects of pyrolysis oven length and erbium precursor on the preparation of discrete erbium-doped silicon nanoparticles. These doped nanoparticles were prepared by the co-pyrolysis of disilane and the volatile complex Er(tmhd)3 (tmhd=2,2,6,6-tetramethyl-3,5-heptanedionato). The particle sizes and size distributions were determined using high resolution and conventional transmission electron microscopy. Erbium-doped silicon nanoparticles exhibit a selected area electron diffraction pattern consistent with the diamond cubic phase and a distinctive dark contrast in the transmission electron microscope. The presence of erbium is confirmed by x-ray energy dispersive spectroscopy. In general, the mean diameter of the individual nanoparticles increases as the length of the pyrolysis oven used during their preparation is increased. © 2000 American Institute of Physics.
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81.07.-b Nanoscale materials and structures: fabrication and characterization
61.46.-w Structure of nanoscale materials
81.05.Cy Elemental semiconductors
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)

InGaN/GaN multiple quantum wells grown by metalorganic vapor phase epitaxy with mass transport

G. Pozina, J. P. Bergman, B. Monemar, M. Iwaya, S. Nitta, H. Amano, and I. Akasaki

Appl. Phys. Lett. 77, 1638 (2000); http://dx.doi.org/10.1063/1.1310175 (3 pages) | Cited 10 times

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We report on studies of In0.12Ga0.88N/GaN heterostructures with three 35-Å-thick quantum wells (QWs) grown on sapphire substrates by metalorganic vapor phase epitaxy with employment of mass transport. The structure is demonstrated to show good structural and optical properties. The threading dislocation density is less than 107 cm−2 for the mass-transport regions. The photoluminescence (PL) spectrum is dominated by the rather narrow near-band gap emission at 2.97 eV with a linewidth of 40 meV. This emission has a typical PL decay time about 5 ns at 2 K within the PL contour. With increasing excitation intensity, an additional transition with longer decay time (about 200 ns) is enhanced at energy about 2.85 eV. The position of this line depends strongly on the excitation power. We explain the data in terms of a model, where the PL is a result of contribution from at least two nonequivalent QWs, which could be realized due to a potential gradient across the layers. © 2000 American Institute of Physics.
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81.05.Ea III-V semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.47.-p Spectroscopy of solid state dynamics

Controlled assembly of two-dimensional colloidal crystals

Q.-H. Wei, D. M. Cupid, and X. L. Wu

Appl. Phys. Lett. 77, 1641 (2000); http://dx.doi.org/10.1063/1.1310210 (3 pages) | Cited 7 times

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Under the influence of capillary forces, colloidal particles embedded in a soap film self-organize to form polycrystalline monolayers when the film is withdrawn from a concentrated suspension. Here, we show that mechanically generated capillary waves on the free surface of the bulk colloidal suspension can cause migration of grain boundaries, and under certain conditions, completely eliminate them. This dramatic effect, we call “mechanic annealing,” provides a robust means of growing two-dimensional single crystals with size that has never been achieved before. The method is expected to be applicable to a variety of self-assembling systems. © 2000 American Institute of Physics.
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82.70.Dd Colloids
68.18.-g Langmuir-Blodgett films on liquids
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