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13 Jan 2003

Volume 82, Issue 2, pp. 155-309

Issue Cover Spotlight Figure

Appl. Phys. Lett. 82, 266 (2003); http://dx.doi.org/10.1063/1.1535271 (3 pages)

Jan Genzer, Daniel A. Fischer, and Kirill Efimenko
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Magneto-optical imaging with diluted magnetic semiconductor quantum wells

C. Gourdon, V. Jeudy, M. Menant, D. Roditchev, Le Anh Tu, E. L. Ivchenko, and G. Karczewski

Appl. Phys. Lett. 82, 230 (2003); http://dx.doi.org/10.1063/1.1534617 (3 pages) | Cited 11 times

Online Publication Date: 6 January 2003

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Heterostructures containing CdMnTe-diluted magnetic semiconductor quantum wells are proposed as magneto-optic layers (MOL) for high-resolution Faraday microscopy at low temperature. The Faraday rotation is enhanced up to 54.4 deg T−1 by embedding the quantum wells in a semiconductor–metal optical cavity. These MOL allowed the observation of the intermediate state pattern in a superconductor layer with spatial and magnetic resolutions of 1 μm and 10 mT, respectively. © 2003 American Institute of Physics.
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78.67.De Quantum wells
78.20.Ls Magneto-optical effects
07.79.Pk Magnetic force microscopes
78.66.Hf II-VI semiconductors
73.40.Ns Metal-nonmetal contacts
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Nearly total spin polarization in La2/3Sr1/3MnO3 from tunneling experiments

M. Bowen, M. Bibes, A. Barthélémy, J.-P. Contour, A. Anane, Y. Lemaître, and A. Fert

Appl. Phys. Lett. 82, 233 (2003); http://dx.doi.org/10.1063/1.1534619 (3 pages) | Cited 279 times

Online Publication Date: 6 January 2003

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We have performed magnetotransport measurements on La2/3Sr1/3MnO3/SrTiO3/La2/3Sr1/3MnO3 magnetic tunnel junctions. A magnetoresistance ratio of more than 1800% is obtained at 4 K, from which we infer an electrode spin polarization of at least 95%. This result strongly underscores the half-metallic nature of mixed-valence manganites and demonstrates their capability as a spin analyzer. The magnetoresistance extends up to temperatures of more than 270 K. We argue that these improvements over most previous works may result from optimizing the patterning process for oxide heterostructures. © 2003 American Institute of Physics.
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75.47.Lx Magnetic oxides
75.30.Mb Valence fluctuation, Kondo lattice, and heavy-fermion phenomena
72.25.Mk Spin transport through interfaces
75.45.+j Macroscopic quantum phenomena in magnetic systems

Ion beam synthesis of superconducting MgB2 thin films

Nianhua Peng, G. Shao, C. Jeynes, R. P. Webb, R. M. Gwilliam, G. Boudreault, D. M. Astill, and W. Y. Liang

Appl. Phys. Lett. 82, 236 (2003); http://dx.doi.org/10.1063/1.1537870 (3 pages) | Cited 11 times

Online Publication Date: 6 January 2003

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Superconducting MgB2 thin films have been fabricated by 80 keV 11B ion implantation into commercial Mg ribbon with 11B doses up to 1018 ions/cm2, followed by thermal annealing at 500 °C. Temperature dependent dc magnetization measurements confirmed superconducting phase transitions between 11 and 18 K for samples containing nanocrystalline MgB2 grains embedded in Mg substrate with a small amount of MgO inclusion. © 2003 American Institute of Physics.
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68.55.-a Thin film structure and morphology
61.72.up Other materials
74.78.-w Superconducting films and low-dimensional structures
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)
74.25.Ha Magnetic properties including vortex structures and related phenomena
61.80.Jh Ion radiation effects
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments
74.10.+v Occurrence, potential candidates
68.37.Lp Transmission electron microscopy (TEM)
61.46.-w Structure of nanoscale materials
61.82.Rx Nanocrystalline materials
74.78.Na Mesoscopic and nanoscale systems
81.07.Bc Nanocrystalline materials
61.72.Qq Microscopic defects (voids, inclusions, etc.)

Ferromagnetism in Mn-implanted ZnO:Sn single crystals

D. P. Norton, S. J. Pearton, A. F. Hebard, N. Theodoropoulou, L. A. Boatner, and R. G. Wilson

Appl. Phys. Lett. 82, 239 (2003); http://dx.doi.org/10.1063/1.1537457 (3 pages) | Cited 217 times

Online Publication Date: 6 January 2003

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We have investigated the magnetic properties of Mn-implanted n-type ZnO single crystals that are codoped with Sn. Theory predicts that room-temperature carrier-mediated ferromagnetism should be possible in manganese-doped p-type ZnO, although Mn-doped n-type ZnO should not be ferromagnetic. While previous efforts report only low-temperature ferromagnetism in Mn-doped ZnO that is n type via shallow donors, we find evidence for ferromagnetism with a Curie temperature of ∼250 K in ZnO that is codoped with Mn and Sn. As a 4+ valence cation, Sn should behave as a doubly ionized donor, thus introducing states deep in the gap. Hysteresis is clearly observed in magnetization versus field curves. Differences in zero-field-cooled and field-cooled magnetization persists up to ∼250 K for Sn-doped ZnO crystals implanted with 3 at. % Mn. Increasing the Mn concentration to 5 at. % significantly reduces the magnetic hysteresis. This latter observation is inconsistent with the origin for ferromagnetism being due to segregated secondary phases, and strongly suggests that a near-room-temperature dilute magnetic semiconducting oxide has been realized. Based on these results, ZnO doped with Mn and Sn may prove promising as a ferromagnetic semiconductor for spintronics. © 2003 American Institute of Physics.
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75.50.Dd Nonmetallic ferromagnetic materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Pp Magnetic semiconductors
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
71.55.Gs II-VI semiconductors

Giant anisotropic magnetostriction in Pr0.5Sr0.5MnO3

R. Mahendiran, M. R. Ibarra, C. Marquina, B. Garcia-Landa, L. Morellon, A. Maignan, B. Raveau, A. Arulraj, and C. N. R. Rao

Appl. Phys. Lett. 82, 242 (2003); http://dx.doi.org/10.1063/1.1537454 (3 pages) | Cited 7 times

Online Publication Date: 6 January 2003

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We show that the polycrystalline perovskite antiferromagnet Pr0.5Sr0.5MnO3 exhibits a giant anisotropic magnetostriction (λt = 1.5×10−3 at T = 25 K and H = 14.2 T) contrary to much smaller λt (<0.1×10−3) found in most other three-dimensional manganites. The value of λt decreases rapidly as the Néel temperature is approached from below, but an unusually high value of λt is also found below the ferromagnetic Curie temperature. We suggest that the magnetic-field-induced antiferromagnetic-to-ferromagnetic transition is accompanied by a structural transition from orthorhombic to tetragonal symmetry and attribute the giant anisotropic effect to the preferential growth of the orbital disordered tetragonal (ferromagnetic) domains along the field direction in the eg-dx2−y2 orbital ordered orthorhombic (antiferromagnetic) matrix. © 2003 American Institute of Physics.
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75.80.+q Magnetomechanical effects, magnetostriction
75.30.Gw Magnetic anisotropy
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.40.-s Critical-point effects, specific heats, short-range order
64.70.K- Solid-solid transitions
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Determination of interface energy band diagram between (100)Si and mixed Al–Hf oxides using internal electron photoemission

V. V. Afanas’ev, A. Stesmans, and W. Tsai

Appl. Phys. Lett. 82, 245 (2003); http://dx.doi.org/10.1063/1.1532550 (3 pages) | Cited 26 times

Online Publication Date: 6 January 2003

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Internal electron photoemission is used to investigate the electronic structure of the Si/Hf–Al oxide interfaces as a function of oxide composition. In the mixed oxides, the energy position and the density of states in the conduction band show little sensitivity to the Hf content. At the same time, the energy band diagram of the Si/oxide interface appears to be very close to that of the Si/Al2O3 interface, suggesting that the conduction band is derived mostly from the states of Al ions. © 2003 American Institute of Physics.
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73.20.At Surface states, band structure, electron density of states
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.50.Pz Photoconduction and photovoltaic effects
73.61.Cw Elemental semiconductors
79.60.Jv Interfaces; heterostructures; nanostructures

Polarization dynamics and retention loss in fatigued PbZr0.4Ti0.6O3 ferroelectric capacitors

B. S. Kang, Jong-Gul Yoon, T. W. Noh, T. K. Song, S. Seo, Y. K. Lee, and J. K. Lee

Appl. Phys. Lett. 82, 248 (2003); http://dx.doi.org/10.1063/1.1534411 (3 pages) | Cited 24 times

Online Publication Date: 6 January 2003

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Short-time retention loss behaviors were investigated for fatigued Pt/PbZr0.4Ti0.6O3/Pt capacitors. In the short-time regime of t<1 s, fatigued capacitors showed a significant loss in retained polarization, which could be well described by a power-law function. This behavior was interpreted in terms of a superposition of polarization relaxations with a relaxation time distribution. The effects of the pulse voltage on the relaxation time distribution suggested that the retention loss should be activated by a depolarization field. As the fatigue stress was applied, the retention loss became worse. This effect can be explained in terms of the increase of the depolarization field, possibly due to the growth of an interfacial passive layer. © 2003 American Institute of Physics.
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84.32.Tt Capacitors
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
77.22.Ej Polarization and depolarization
77.22.Gm Dielectric loss and relaxation
77.80.Fm Switching phenomena
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates

High-Tm relaxor ferroelectrics: 0.3BiScO3–0.6PbTiO3–0.1Pb(Mn1/3Nb2/3)O3

Jungho Ryu, Shashank Priya, and Kenji Uchino

Appl. Phys. Lett. 82, 251 (2003); http://dx.doi.org/10.1063/1.1536028 (3 pages) | Cited 14 times

Online Publication Date: 6 January 2003

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High-Tm relaxor materials are being developed for high-temperature high-power density electrotransduction applications and high-temperature capacitors in automobile applications. A relaxor ferroelectric material of composition 0.3BiScO3–0.6PbTiO3–0.1Pb(Mn1/3Nb2/3)O3 having a very high dielectric maximum of ∼ 350 °C is reported. The relaxor behavior is confirmed by studying polarization relaxation and frequency and temperature dependent dielectric behavior. The dielectric constant in the low-temperature region of 10 °C<T<150 °C is found to be independent of the frequency with a temperature gradient of ∂ε/∂T = 2.5/°C. The room-temperature magnitude of dielectric constant is ∼ 600. © 2003 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.22.Ch Permittivity (dielectric function)
77.80.Dj Domain structure; hysteresis
77.22.Ej Polarization and depolarization

Ultraviolet-induced discharge currents and reduction of the piezoelectric coefficient in cellular polypropylene films

Axel Mellinger, Francisco Camacho González, and Reimund Gerhard-Multhaupt

Appl. Phys. Lett. 82, 254 (2003); http://dx.doi.org/10.1063/1.1537051 (3 pages) | Cited 9 times

Online Publication Date: 6 January 2003

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Photostimulated discharge spectroscopy of cellular polypropylene films between 200 and 400 nm showed the existence of at least three distinct trapping levels at 4.6, 5.6, and 6.3 eV. The effects of UV irradiation on the piezoelectric d33 coefficient was studied by monitoring thickness-extension resonances in the dielectric spectrum. Prolonged irradiation at wavelengths below 210 nm led to a reduction of the piezoelectric coefficient, caused by partial discharge of the polymer foam.© 2003 American Institute of Physics.
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77.84.Jd Polymers; organic compounds
77.55.-g Dielectric thin films
61.82.Pv Polymers, organic compounds
77.65.Bn Piezoelectric and electrostrictive constants
77.22.Jp Dielectric breakdown and space-charge effects
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
71.55.Ht Other nonmetals
73.50.Pz Photoconduction and photovoltaic effects
73.61.Ph Polymers; organic compounds
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Controlling the surface enhanced Raman effect via the nanoshell geometry

J. B. Jackson, S. L. Westcott, L. R. Hirsch, J. L. West, and N. J. Halas

Appl. Phys. Lett. 82, 257 (2003); http://dx.doi.org/10.1063/1.1534916 (3 pages) | Cited 173 times

Online Publication Date: 6 January 2003

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Systematic variation of the internal geometry of a dielectric core-metal shell nanoparticle allows the local electromagnetic field at the nanoparticle surface to be precisely controlled. The strength of the field as a function of core and shell dimension is measured by monitoring the surface enhanced Raman scattering (SERS) response of nonresonant molecular adsorbates (para-mercaptoaniline) bound to the nanoparticle surface. The SERS enhancement appears to be directly and exclusively due to nanoparticle geometry. Effective SERS enhancements of 106 are observable in aqueous solution, which correspond to absolute enhancements of 1012 when reabsorption of Raman emission by nearby nanoparticles is taken into account. © 2003 American Institute of Physics.
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78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.30.-j Infrared and Raman spectra
61.46.-w Structure of nanoscale materials

Far-infrared absorption spectra and properties of SnO2 nanorods

Yingkai Liu, Yi Dong, and Guanghou Wang

Appl. Phys. Lett. 82, 260 (2003); http://dx.doi.org/10.1063/1.1535745 (3 pages) | Cited 9 times

Online Publication Date: 6 January 2003

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Gray-colored materials synthesized by calcining the precursor powders, which were produced in a microemulsion, are identified to be rutile structured SnO2 nanorods 20–45 nm in diameter and several micrometers in length by x-ray diffraction, transmission with electron microscopy, and high-resolution transmission microscopy. Conspicuous far-infrared (FIR) absorption spectrum platform peaks with widths of up to 61.6 and 119 cm−1 are observed, and are explained as the overlap of the surface modes of cylindrical and spheroid particles. Good agreement is achieved between FIR platform peaks and calculated results. © 2003 American Institute of Physics.
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78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.30.Hv Other nonmetallic inorganics
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
68.35.Ja Surface and interface dynamics and vibrations
78.68.+m Optical properties of surfaces

Thermal stability of Ti-catalyzed Si nanowires

T. I. Kamins, X. Li, and R. Stanley Williams

Appl. Phys. Lett. 82, 263 (2003); http://dx.doi.org/10.1063/1.1534616 (3 pages) | Cited 15 times

Online Publication Date: 6 January 2003

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The stability of long, narrow Si nanowires grown by catalytic decomposition of a Si-containing gas during annealing was investigated because their use in devices will depend on their stability during subsequent processing. The nanowires can be annealed without visible change well above 900 °C in N2 after air exposure. However, annealing in a H2 ambient more readily degrades their structure. Nanowires without a native surface oxide are stable up to 850 °C, but change significantly at 900 °C. Surface diffusion appears to be sufficient to allow constant-diameter nanowire regions to form.© 2003 American Institute of Physics.
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68.65.La Quantum wires (patterned in quantum wells)
81.07.Vb Quantum wires
68.60.Dv Thermal stability; thermal effects
81.16.Hc Catalytic methods
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)

Combinatorial near-edge x-ray absorption fine structure: Simultaneous determination of molecular orientation and bond concentration on chemically heterogeneous surfaces

Jan Genzer, Daniel A. Fischer, and Kirill Efimenko

Appl. Phys. Lett. 82, 266 (2003); http://dx.doi.org/10.1063/1.1535271 (3 pages) | Cited 4 times

Online Publication Date: 6 January 2003

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We show that simultaneous molecular orientation and bond chemistry of planar chemically heterogeneous surfaces can be obtained by combining near-edge x-ray absorption fine structure (NEXAFS) spectroscopy and rastering the incident x-ray beam on the specimen. This rastering produces serially two-dimensional NEXAFS images in space and energy, revealing information about the chemistry (including bond concentration) and orientation of the surface-bound molecules with submillimeter planar spatial resolution and submonolayer molecular sensitivity. We illustrate the power of the combinatorial NEXAFS method by simultaneously probing the concentration and molecular orientation of semifluorinated (SF) molecules in double-SF molecular gradients on flat silica substrates. © 2003 American Institute of Physics.
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61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.
78.70.Dm X-ray absorption spectra
68.43.Fg Adsorbate structure (binding sites, geometry)
68.35.Dv Composition, segregation; defects and impurities
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Relationship between interfacial nitrogen concentration and activation energies of fixed-charge trapping and interface state generation under bias-temperature stress condition

Shyue Seng Tan, T. P. Chen, C. H. Ang, and L. Chan

Appl. Phys. Lett. 82, 269 (2003); http://dx.doi.org/10.1063/1.1537053 (3 pages) | Cited 15 times

Online Publication Date: 6 January 2003

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The influence of nitrogen concentration at a nitrided oxide/silicon interface on the activation energies of both near-interface fixed-charge trapping and interface state generation caused by negative bias temperature instability stress has been studied quantitatively. It is observed that the charge trapping and the interface state generation have about the same activation energy for a given interfacial nitrogen concentration. In addition, their activation energies are found to follow the same dependence on the nitrogen concentration. The results suggest that the charge trapping and the interface state generation have the same origin. A discussion on the mechanism of the nitrogen effect on the charge trapping and interface state generation is presented. © 2003 American Institute of Physics.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.20.At Surface states, band structure, electron density of states
68.35.Fx Diffusion; interface formation

Crystalline boron nanowires

Y. Q. Wang and X. F. Duan

Appl. Phys. Lett. 82, 272 (2003); http://dx.doi.org/10.1063/1.1536269 (3 pages) | Cited 22 times

Online Publication Date: 6 January 2003

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Crystalline boron nanowires were produced through post-annealing amorphous boron nanowires synthesized by rf magnetron sputtering. High-resolution transmission electron microscopy was used to characterize the microstructure of the crystalline boron nanowires. Selected-area electron diffraction studies showed that the crystalline boron nanowires belong to a rhombohedral structure (β-boron), with lattice parameters of a = 10.95 Å and c = 23.82 Å. Electron energy-loss spectroscopy was used to characterize the chemical composition of the boron nanowires. © 2003 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
81.07.Vb Quantum wires
81.40.Gh Other heat and thermomechanical treatments
79.20.Uv Electron energy loss spectroscopy
68.37.Lp Transmission electron microscopy (TEM)

Carbon-nanotube-based nonvolatile memory with oxide–nitride–oxide film and nanoscale channel

Won Bong Choi, Soodoo Chae, Eunju Bae, Jo-Won Lee, Byoung-Ho Cheong, Jae-Ryoung Kim, and Ju-Jin Kim

Appl. Phys. Lett. 82, 275 (2003); http://dx.doi.org/10.1063/1.1536713 (3 pages) | Cited 34 times

Online Publication Date: 6 January 2003

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We have fabricated a single-wall carbon-nanotube (CNT)-based nonvolatile memory device using SiO2–Si3N4–SiO2 (ONO) layers as a storage node. The memory device is composed of a top gate structure with a channel width of a few nanometers and the ONO layer embedded between CNT and gate electrode. When the bias voltage between the CNT and gate electrode increases to 4 V, charges are tunneled out from CNT surfaces and captured to the traps in the ONO layers. Stored charges on the trap sites make the threshold voltage shift of 60 mV and is independent of charging time, suggesting that the ONO has traps with a quasiquantized energy state. The quantized state is related to the localized high electric field associated with CNT channel. The CNT-field-effect transistor with an ONO storage node could be used for an ultrahigh-density nonvolatile memory. © 2003 American Institute of Physics.  
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85.35.Kt Nanotube devices
73.63.Fg Nanotubes
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Self-organized growth of single crystals of nanopores

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

Appl. Phys. Lett. 82, 278 (2003); http://dx.doi.org/10.1063/1.1537868 (3 pages) | Cited 37 times

Online Publication Date: 6 January 2003

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Self-organized single crystalline two-dimensional hexagonal arrays of pores in InP semiconductor compound are reported. We show that the self-arrangement of pores can be obtained on n-type substrates with (100) and (111) orientations. The long-range order in pore distribution evidenced in (100)InP samples proves to be favored by the so-called nucleation layer exhibiting branching pores oriented along 〈111〉 directions. The combination of long-range order with self-induced diameter oscillations is shown to be promising for nonlithographic growth of three-dimensional pore crystals. © 2003 American Institute of Physics.
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81.16.Dn Self-assembly
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.05.Ea III-V semiconductors
81.05.Rm Porous materials; granular materials
61.46.-w Structure of nanoscale materials
68.55.A- Nucleation and growth

Formation mechanism of TiO2 nanotubes

B. D. Yao, Y. F. Chan, X. Y. Zhang, W. F. Zhang, Z. Y. Yang, and N. Wang

Appl. Phys. Lett. 82, 281 (2003); http://dx.doi.org/10.1063/1.1537518 (3 pages) | Cited 177 times

Online Publication Date: 6 January 2003

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Transmission electron microscopic observation showed that TiO2 nanotubes synthesized via a simple hydrothermal chemical process formed a crystalline structure with open-ended and multiwall morphologies. Unlike multiwalled carbon nanotubes, the TiO2 nanotube walls were not seamless. During alkali treatment, crystalline TiO2 raw material underwent delamination in the alkali solution to produce single-layer TiO2 sheets. TiO2 nanotubes were formed by rolling up the single-layer TiO2 sheets with a rolling-up vector of [001] and attracting other sheets to surround the tubes. © 2003 American Institute of Physics.
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81.07.De Nanotubes
61.46.-w Structure of nanoscale materials
68.37.Lp Transmission electron microscopy (TEM)
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Inverted top-emitting organic light-emitting diodes using sputter-deposited anodes

T. Dobbertin, M. Kroeger, D. Heithecker, D. Schneider, D. Metzdorf, H. Neuner, E. Becker, H.-H. Johannes, and W. Kowalsky

Appl. Phys. Lett. 82, 284 (2003); http://dx.doi.org/10.1063/1.1535743 (3 pages) | Cited 57 times

Online Publication Date: 6 January 2003

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We demonstrate vacuum-sublimed topside-emitting inverted organic light-emitting diodes (IOLEDs) employing low-power radio-frequency magnetron sputter-deposited indium tin oxide (ITO) anodes. The device introduces a two-step sputtering sequence to reduce damage incurred by the sputtering process, paired with a buffer- and hole-transporting material Pentacene. Systematic optimization of the organic growth sequence focused on device performance characterized by current and luminous efficiencies, suggest the incorporation of rather thick Pentacene layers. The optimized thickness is obtained as a trade-off between light absorption and protective properties of Pentacene. The optically and electrically undoped organic multilayer devices capped with 90-nm ITO exhibit high current efficiencies of 3.9 cd/A at a raised luminance level of 1.500 cd/m2, combined with luminous efficiencies of 0.7 lm/W. The inverted configuration allows for integration of organic light-emitting diodes (OLEDs) with preferentially used n-channel field-effect transistors for driver backplanes in active matrix OLED displays. © 2003 American Institute of Physics.
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85.60.Jb Light-emitting devices
85.60.Pg Display systems
81.15.Cd Deposition by sputtering
42.79.Kr Display devices, liquid-crystal devices

Understanding shunting behavior in hot-wire-deposited amorphous silicon solar cells

M. K. van Veen and R. E. I. Schropp

Appl. Phys. Lett. 82, 287 (2003); http://dx.doi.org/10.1063/1.1536710 (3 pages) | Cited 3 times

Online Publication Date: 6 January 2003

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Amorphous silicon solar cells, in which the absorbing layer is deposited using the hot-wire chemical vapor deposition (CVD) technique, have potential advantages over solar cells made with the standard plasma enhanced CVD technique. Although it is possible to make high-quality solar cells, many cells occasionally show shunting behavior and better control over the variation in cell performance must be obtained. In this letter, we prove that this behavior is directly correlated with the filament age, and we present different methods for avoiding shunted cells and for improving the reproducibility of cell performance. © 2003 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.05.Gc Amorphous semiconductors
84.60.Jt Photoelectric conversion
68.55.-a Thin film structure and morphology
73.61.Jc Amorphous semiconductors; glasses

AlN/diamond heterojunction diodes

C. R. Miskys, J. A. Garrido, C. E. Nebel, M. Hermann, O. Ambacher, M. Eickhoff, and M. Stutzmann

Appl. Phys. Lett. 82, 290 (2003); http://dx.doi.org/10.1063/1.1532545 (3 pages) | Cited 30 times

Online Publication Date: 6 January 2003

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An aluminum nitride/diamond p–n heterojunction has been realized by plasma-induced molecular-beam epitaxy growth of AlN on (100) diamond. The epitaxial nature of this heterojunction has been confirmed by high-resolution x-ray diffraction. The silicon-doped AlN film (n-type) on the natural boron-doped (p-type) diamond substrate formed a heterobipolar diode with good rectifying properties and surprisingly efficient light emission in the spectral range from 2.7 to 4.8 eV under forward bias. Results concerning the structural, electrical, and optical characterization of the AlN/diamond heterojunction are reported in this letter. © 2003 American Institute of Physics.
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85.60.Jb Light-emitting devices
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
85.30.Kk Junction diodes

Capacitively coupled hot-electron nanobolometer as far-infrared photon counter

Dragoş-Victor Anghel and Leonid Kuzmin

Appl. Phys. Lett. 82, 293 (2003); http://dx.doi.org/10.1063/1.1536728 (3 pages) | Cited 7 times

Online Publication Date: 6 January 2003

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We show theoretically that hot-electron nanobolometers consisting of a small piece of normal metal, capacitively coupled to a superconducting antenna through a pair of normal metal–insulator–superconductor (NIS) tunnel junctions may be used as far-infrared photon counters. To make the device most effective at high counting rates, we suggest the use of the bolometer in the simplest configuration, when the NIS tunnel junctions are used as both an electron cooler and thermometer. The absorbtion of the photon in the normal metal produces a pulse in the electron temperature, which is measured by the NIS junctions. The counter may resolve photons up to 0.3–0.4 mm wavelength and has a typical re-equilibration time constant of about 20 ns. © 2003 American Institute of Physics.
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85.25.Pb Superconducting infrared, submillimeter and millimeter wave detectors
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.25.Cp Josephson devices
74.25.N- Response to electromagnetic fields

Damage coefficient in high-temperature particle- and γ-irradiated silicon p–i–n diodes

H. Ohyama, K. Takakura, K. Hayama, Satoshi Kuboyama, Yasushi Deguchi, Sumio Matsuda, E. Simoen, and C. Claeys

Appl. Phys. Lett. 82, 296 (2003); http://dx.doi.org/10.1063/1.1536715 (3 pages) | Cited 1 time

Online Publication Date: 6 January 2003

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The impact of high-temperature neutron, electron, and γ-irradiations on the dark current of silicon p–i–n junctions is described in terms of a damage coefficient KI. It is shown that this KI is thermally activated and reduces for increasing irradiation temperature. The same activation energy is retrieved when studying the isochronal annealing behavior of a set of room-temperature irradiated diodes. This leads to a simple method to predict the high-temperature KI from only room-temperature irradiations combined with a thermal annealing study. © 2003 American Institute of Physics.
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85.30.Kk Junction diodes
61.82.Fk Semiconductors
61.80.Ed γ-ray effects
61.80.Hg Neutron radiation effects
61.80.Fe Electron and positron radiation effects
85.30.De Semiconductor-device characterization, design, and modeling
61.72.Cc Kinetics of defect formation and annealing

Increased efficiency in vertically segregated thin-film conjugated polymer blends for light-emitting diodes

N. Corcoran, A. C. Arias, J. S. Kim, J. D. MacKenzie, and R. H. Friend

Appl. Phys. Lett. 82, 299 (2003); http://dx.doi.org/10.1063/1.1537049 (3 pages) | Cited 50 times

Online Publication Date: 6 January 2003

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The effect of film morphology on the performance of conjugated polymer-blend light-emitting diodes (LEDs) has been investigated. Vertically segregated structures have been fabricated by varying the spinning conditions and solvents used so that phase separation normal to the substrate is induced. External quantum efficiencies show that LEDs made with vertically segregated structures are between 25% and 100% more efficient than laterally segregated LEDs, depending on the scale of lateral phase separation. © 2003 American Institute of Physics.
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85.60.Jb Light-emitting devices
68.55.-a Thin film structure and morphology
64.75.-g Phase equilibria

A general relation between the ranges of stability of electrostatic actuators under charge or voltage control

Ofir Bochobza-Degani, David Elata, and Yael Nemirovsky

Appl. Phys. Lett. 82, 302 (2003); http://dx.doi.org/10.1063/1.1536251 (3 pages) | Cited 8 times

Online Publication Date: 6 January 2003

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Pull-in instability is a crucial effect in electrostatically-actuated microelectromechanical devices. This phenomenon was recently shown to occur under both voltage and charge control. So far, for all known cases, it has been shown that, under charge excitation, electrostatic actuators have a larger range of stability than under voltage excitation. No counter-examples are known, and whether this is a general rule for electrostatic actuators is an open question. In this work, a general proof is presented that shows this is indeed a fundamental rule for general electrostatic actuators. © 2003 American Institute of Physics.
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85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
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