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29 Jul 2002

Volume 81, Issue 5, pp. 789-944

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Optical waveguides fabricated by pulsed-laser deposition of SiO2 films with different refractive indices

M. Okoshi, M. Kuramatsu, and N. Inoue

Appl. Phys. Lett. 81, 789 (2002); http://dx.doi.org/10.1063/1.1496134 (3 pages)

Online Publication Date: 22 July 2002

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We deposited pure SiO2 films with different refractive indices by pulsed-laser deposition with silicone targets. The refractive index of the films could be controlled by the deposition rate. Lowering of the deposition rate helped to make a dense film, showing higher refractive index. A 0.4-μm-thick SiO2 cladding film deposited at 0.1 nm/pulse was first formed on the whole surface of a Si wafer, and then a 1-μm-thick SiO2 core film at 0.05 nm/pulse was fabricated in a line on the sample. The sample functioned as an optical waveguide for a 633 nm line of He–Ne laser. © 2002 American Institute of Physics.
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42.82.Cr Fabrication techniques; lithography, pattern transfer
42.79.Gn Optical waveguides and couplers
42.82.Et Waveguides, couplers, and arrays
81.15.Fg Pulsed laser ablation deposition
42.79.Wc Optical coatings
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Europium complex as a highly efficient red emitter in electroluminescent devices

Pei-Pei Sun, Jiun-Pey Duan, Huai-Ting Shih, and Chien-Hong Cheng

Appl. Phys. Lett. 81, 792 (2002); http://dx.doi.org/10.1063/1.1497714 (3 pages) | Cited 66 times

Online Publication Date: 22 July 2002

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Several devices using a europium complex Eu(TTA)3(DPPz)(TTA = 2-thenoyltrifluoroacetonate, DPPz = dipyrido[3,2-a:2′,3′-c]phenazine) as dopant emitter were fabricated. The performances of these devices are among the best reported for devices incorporating a europium complex as a red emitter. One such device with structure TPD (50 nm)/Eu:CBP (4.5%, 30 nm)/BCP (30 nm)/Alq (25 nm) exhibits an external quantum efficiency 2.1%, current efficiency 4.4 cd/A, power efficiency 2.1 lm/W, and brightness 1670 cd/m2. © 2002 American Institute of Physics.
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78.60.Fi Electroluminescence
85.60.Jb Light-emitting devices

Polymeric multimode waveguide based electro-optic modulator with a vertically configured dumping planar waveguide

Xuejun Lu, Chiou-hung Jang, Dechang An, Qingjun Zhou, Lin Sun, Xuping Zhang, Ray T. Chen, and Dan Dawson

Appl. Phys. Lett. 81, 795 (2002); http://dx.doi.org/10.1063/1.1497186 (3 pages) | Cited 3 times

Online Publication Date: 22 July 2002

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An electro-optic modulator based on a polymeric multimode waveguide coupler was developed. A guiding multimode waveguide with a vertically configured dumping planar waveguide was employed in the design to increase the device packing density. A modulation depth of 91% at 1330 nm was experimentally achieved. This device shows that the multimode optical waveguide with the vertically configured dumping planar waveguide is promising in electro-optic modulator designs. This modulator can be used in multimode optical interconnection systems such as data communications and fiber sensor networks. © 2002 American Institute of Physics.
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42.82.Gw Other integrated-optical elements and systems
42.79.Hp Optical processors, correlators, and modulators
42.79.Gn Optical waveguides and couplers
42.70.Jk Polymers and organics

Design of one-dimensional random surfaces with specified scattering properties

E. R. Méndez, E. E. García-Guerrero, T. A. Leskova, A. A. Maradudin, J. Muñoz-López, and I. Simonsen

Appl. Phys. Lett. 81, 798 (2002); http://dx.doi.org/10.1063/1.1495900 (3 pages) | Cited 9 times

Online Publication Date: 22 July 2002

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We propose a method for designing a one-dimensional random perfectly conducting surface which, when illuminated by a plane wave, scatters it with a prescribed angular distribution of intensity. The method is applied to the design of a surface that scatters light uniformly within a specified range of scattering angles, and produces no scattering outside this range. It is tested by computer simulations, and a procedure for fabricating such surfaces on photoresist is described. © 2002 American Institute of Physics.
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42.25.Fx Diffraction and scattering

Top-emission ultraviolet light-emitting diodes with peak emission at 280 nm

A. Yasan, R. McClintock, K. Mayes, S. R. Darvish, P. Kung, and M. Razeghi

Appl. Phys. Lett. 81, 801 (2002); http://dx.doi.org/10.1063/1.1497709 (2 pages) | Cited 43 times

Online Publication Date: 22 July 2002

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We demonstrate light emission at 280 nm from UV light-emitting diodes consisting of AlInGaN/AlInGaN multiple quantum wells. Turn-on voltage of the devices is ∼5 V with a differential resistance of ∼40 Ω. The peak emission wavelength redshifts ∼1 nm at high injection currents. © 2002 American Institute of Physics.
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85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Electric-field tuning of the Rabi splitting in a superlattice-embedded microcavity

J. H. Dickerson, J. K. Son, E. E. Mendez, and A. A. Allerman

Appl. Phys. Lett. 81, 803 (2002); http://dx.doi.org/10.1063/1.1495901 (3 pages) | Cited 1 time

Online Publication Date: 22 July 2002

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We have demonstrated comprehensive electric field tuning of the Rabi splitting between the excitonic and photonic modes of a superlattice-embedded microcavity. Using photocurrent spectroscopy to measure the coupling between the modes, we have tuned the microcavity to the maximum possible splitting. We have observed a marked increase in the splitting from 4.5 to 11.5 meV, due to the electric-field enhancement of the superlattice exciton’s oscillator strength and the oscillator strength’s subsequent decrease due to the quantum confined Stark effect. As well, we have determined the oscillator strength for the exciton, finding good agreement with theoretical and experimental values. © 2002 American Institute of Physics.
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78.20.Jq Electro-optical effects
78.67.-n Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
73.21.Cd Superlattices
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.35.-y Excitons and related phenomena

Organic single-layer electroluminescent devices fabricated on CuOx-coated indium tin oxide substrate

Wenping Hu and Michio Matsumura

Appl. Phys. Lett. 81, 806 (2002); http://dx.doi.org/10.1063/1.1497441 (2 pages) | Cited 18 times

Online Publication Date: 22 July 2002

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Organic single-layer devices were fabricated by depositing tris(8-quinolinato)aluminum (ALQ) layer on CuOx-coated indium tin oxide (ITO) substrates. These organic single-layer devices showed luminance as high as 2500 cd/m2, and the luminance-current efficiency reached 1.2 cd/A, which was higher than that of single-layer devices fabricated on conventional ITO substrates by eight times. The improvement in the electroluminescent properties of these devices was attributed to the enhanced hole injection from the CuOx-coated ITO into the ALQ layer. © 2002 American Institute of Physics.
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85.60.Jb Light-emitting devices

Lasing from semiconductor microring on the end of an optical fiber

B. Corbett, P. Lambkin, G. H. Wu, J. Houlihan, and G. Huyet

Appl. Phys. Lett. 81, 808 (2002); http://dx.doi.org/10.1063/1.1496496 (3 pages) | Cited 3 times

Online Publication Date: 22 July 2002

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Isolated InGaAsP microrings with an outer diameter of 5.8 μm, a width of 1 μm, and a thickness of 0.41 μm were fabricated by epitaxial separation. Individual devices were bonded to multimode optical fiber using Van der Waals forces and optically pumped through the fiber. Lasing around 1505 nm was measured under pulsed and cw pumping at room temperature. The threshold pump power for pulsed operation was estimated to be 38 and 80 μW for cw operation. Multiple radial and azimuthal modes were present due to strong, three-dimensional confinement. Under strong pulsed pumping thermal effects caused the emission wavelength to chirp. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.55.Sa Microcavity and microdisk lasers
42.60.Fc Modulation, tuning, and mode locking

Enhanced fundamental and self-frequency-doubling laser emission efficiency in 4F3/2 directly pumped Nd-activated nonlinear crystals: The case of GdCa4O(BO3)3

V. Lupei, G. Aka, and D. Vivien

Appl. Phys. Lett. 81, 811 (2002); http://dx.doi.org/10.1063/1.1494119 (3 pages) | Cited 10 times

Online Publication Date: 22 July 2002

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The possibilities of improvement of laser emission characteristics and reduction of heat generation by direct pumping at 887 nm into the emitting level 4F3/2 of Nd3+ in the self-frequency-doubling crystal Nd–GdCOB [GdCa4O(BO3)3] are discussed. Enhanced laser emission performances at fundamental 1060 nm, and especially at the self-frequency-doubled 530 nm wavelengths as compared to the traditional 811 nm pumping into the 4F5/2 level, are demonstrated. © 2002 American Institute of Physics.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
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Role of trace impurities in large-volume noble gas atmospheric-pressure glow discharges

Xiaohui Yuan and Laxminarayan L. Raja

Appl. Phys. Lett. 81, 814 (2002); http://dx.doi.org/10.1063/1.1497445 (3 pages) | Cited 28 times

Online Publication Date: 22 July 2002

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A computational study of capacitively coupled atmospheric-pressure glow discharges in high-purity helium is presented, and the role of trace impurities in such noble gas plasmas is established. Trace impurities result in generation of significant amounts of charged species through Penning ionization and charge exchange reactions. The altered charged species balance in the plasma causes a large change in the discharge impedance when compared to a completely pure noble gas discharge. Peak electron temperatures of the order of 50 000 K and electron densities of order 1011 cm−3 are predicted. Significant electron generation is observed inside the sheath region due to the highly collisional nature of the plasma. This study underscores the importance of modeling the effect of even trace amounts of impurities in noble gas atmospheric-pressure glow discharges. © 2002 American Institute of Physics.
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52.80.Hc Glow; corona
52.25.Vy Impurities in plasmas
52.40.Kh Plasma sheaths
52.20.Hv Atomic, molecular, ion, and heavy-particle collisions
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Optical properties of strain-balanced SiGe planar microcavities with Ge dots on Si substrates

K. Kawaguchi, M. Morooka, K. Konishi, S. Koh, and Y. Shiraki

Appl. Phys. Lett. 81, 817 (2002); http://dx.doi.org/10.1063/1.1496142 (3 pages) | Cited 12 times

Online Publication Date: 22 July 2002

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SiGe microcavities with Ge dots were fabricated by employing strain-balanced SiGe/Si Bragg reflectors, and it was observed that photoluminescence from Ge dots embedded in the microcavity structure was significantly modulated due to the cavity effect. The characteristic luminescence of the microcavity was observed up to 200 K, and the thermal activation energy of the luminescence was largely improved compared with that of cavities with quantum wells. © 2002 American Institute of Physics.
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78.67.Hc Quantum dots
81.07.Ta Quantum dots
78.55.Hx Other solid inorganic materials
78.55.Ap Elemental semiconductors
68.60.Bs Mechanical and acoustical properties
68.65.Hb Quantum dots (patterned in quantum wells)
42.55.Sa Microcavity and microdisk lasers
81.05.Cy Elemental semiconductors
81.05.Hd Other semiconductors
78.66.Db Elemental semiconductors and insulators

Enhanced growth of CoSi2 on epitaxial Si0.7Ge0.3 with a sacrificial amorphous Si interlayer

W. W. Wu, T. F. Chiang, S. L. Cheng, S. W. Lee, L. J. Chen, Y. H. Peng, and H. H. Cheng

Appl. Phys. Lett. 81, 820 (2002); http://dx.doi.org/10.1063/1.1494103 (3 pages) | Cited 9 times

Online Publication Date: 22 July 2002

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Enhanced growth of CoSi2 on epitaxial Si0.7Ge0.3 has been achieved with an interposing amorphous-Si (a-Si) layer. The a-Si layer was used as a sacrificial layer to prevent Ge segregation, decrease the growth temperature, as well as maintain the interface flatness and morphological stability in forming CoSi2 on Si0.7Ge0.3 grown by molecular beam eptiaxy. The process promises to be applicable to the fabrication of high-speed Si–Ge devices. © 2002 American Institute of Physics.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
85.40.Ls Metallization, contacts, interconnects; device isolation
68.55.A- Nucleation and growth
68.37.Lp Transmission electron microscopy (TEM)
81.05.Gc Amorphous semiconductors
81.05.Cy Elemental semiconductors
81.05.Hd Other semiconductors
73.40.Ns Metal-nonmetal contacts
68.35.Dv Composition, segregation; defects and impurities
68.35.Ct Interface structure and roughness
61.72.Cc Kinetics of defect formation and annealing
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Tensile elongation (110%) observed in ultrafine-grained Zn at room temperature

X. Zhang, H. Wang, R. O. Scattergood, J. Narayan, C. C. Koch, A. V. Sergueeva, and A. K. Mukherjee

Appl. Phys. Lett. 81, 823 (2002); http://dx.doi.org/10.1063/1.1494866 (3 pages) | Cited 32 times

Online Publication Date: 22 July 2002

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Tensile tests were performed for Zn at room temperature, which show elongations of 110%–20% for average grain sizes of 240–23 nm, respectively. The ductility of ultrafine-grained and nanocrystalline Zn was found to decrease with grain size refinement. The deformation mechanisms in ultrafine-grained Zn are believed to be a mixture of grain boundary sliding of small nanograins and intra-grain dislocation creep within the large grains. © 2002 American Institute of Physics.
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81.40.Lm Deformation, plasticity, and creep
81.70.Bt Mechanical testing, impact tests, static and dynamic loads
62.25.-g Mechanical properties of nanoscale systems
62.20.F- Deformation and plasticity
61.46.-w Structure of nanoscale materials
81.07.Bc Nanocrystalline materials
81.40.Gh Other heat and thermomechanical treatments
62.20.Hg Creep

Dependence of boron cluster dissolution on the annealing ambient

Ljubo Radic, Aaron D. Lilak, and Mark E. Law

Appl. Phys. Lett. 81, 826 (2002); http://dx.doi.org/10.1063/1.1496505 (3 pages) | Cited 8 times

Online Publication Date: 22 July 2002

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Boron is introduced into silicon via implantation to form p-type layers. This process creates damage in the crystal that upon annealing causes enhanced diffusion and clustering of the boron layer. Reactivation of the boron is not a well-understood process. In this letter we experimentally investigate the effect of the annealing ambient on boron reactivation kinetics. An oxidizing ambient which injects silicon interstitials is compared to an inert ambient. Contrary to published theory, an excess of interstitials does not accelerate the reactivation process. © 2002 American Institute of Physics.
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66.30.J- Diffusion of impurities
64.75.-g Phase equilibria
61.72.Cc Kinetics of defect formation and annealing
61.80.Jh Ion radiation effects
61.72.uf Ge and Si
61.82.Fk Semiconductors
61.72.J- Point defects and defect clusters
61.72.S- Impurities in crystals
66.30.Lw Diffusion of other defects

Short Bragg mirrors with adiabatic modal conversion

D. Peyrade, E. Silberstein, Ph. Lalanne, A. Talneau, and Y. Chen

Appl. Phys. Lett. 81, 829 (2002); http://dx.doi.org/10.1063/1.1497722 (3 pages) | Cited 24 times

Online Publication Date: 22 July 2002

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A silicon-on-insulator waveguide-based microcavity with short tapers has been realized by incorporating two identical eight-groove tapers at the two reflector extremities. The microstructure has an overall length of 14 μm and consists of two first-order Bragg mirrors with narrow slits (90 nm) and of four series of slits with progressively varying widths (tapers). A comparison with a nontapered cavity evidences the beneficial effect of the taper, a lowering of the radiation losses. © 2002 American Institute of Physics.
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42.82.Gw Other integrated-optical elements and systems
42.79.Bh Lenses, prisms and mirrors
42.79.Gn Optical waveguides and couplers

Femtosecond laser induced crystallization and permanent relief grating structures in amorphous inorganic (In2O3+1 wt % TiO2) films

Shigeru Katayama, Naoto Tsutsumi, Toshitaka Nakamura, Mika Horiike, and Kazuyuki Hirao

Appl. Phys. Lett. 81, 832 (2002); http://dx.doi.org/10.1063/1.1497713 (3 pages) | Cited 4 times

Online Publication Date: 22 July 2002

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This letter presents an investigation of crystalline relief grating structures induced by irradiation of near-infrared femtosecond laser pulses on an amorphous inorganic (In2O3+1 wt % TiO2) film. The shapes of crystallized relief structures were sensitive to the scanning rate and the focused point height of irradiation, and the optimized irradiation condition gave cone-shaped cross section structures. Selective wet etching on unirradiated amorphous regions using a 3% hydrochloric acid solution could make sharper relief grating structures of crystalline regions. Diffraction efficiency of the relief grating structures with Au coating was measured, and it was confirmed that first-order diffraction, efficiencies were approximately 40% and 20% for etched and nonetched samples, respectively. © 2002 American Institute of Physics.
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42.62.-b Laser applications
42.79.Dj Gratings
68.35.Rh Phase transitions and critical phenomena
79.20.Ds Laser-beam impact phenomena
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
81.65.Cf Surface cleaning, etching, patterning
61.72.Cc Kinetics of defect formation and annealing

Magnetron sputtered epitaxial single-phase Ti3SiC2 thin films

J.-P. Palmquist, U. Jansson, T. Seppänen, P. O. Å. Persson, J. Birch, L. Hultman, and P. Isberg

Appl. Phys. Lett. 81, 835 (2002); http://dx.doi.org/10.1063/1.1494865 (3 pages) | Cited 58 times

Online Publication Date: 22 July 2002

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We report on the synthesis and characterization of epitaxial single-crystalline Ti3SiC2 films (Mn+1AXn-phase). Two original deposition techniques are described, (i) magnetron sputtering from Ti3SiC2 compound target and (ii) sputtering from individual titanium and silicon targets with co-evaporated C60 as carbon source. Epitaxial Ti3SiC2 films of single-crystal quality were grown at 900 °C with both techniques. Epitaxial TiC(111) deposited in situ on MgO(111) by Ti sputtering using C60 as carbon source was used to nucleate the Ti3SiC2 films. The epitaxial relationship was found to be Ti3SiC2(0001)//TiC(111)//MgO(111) with the in-plane orientation Ti3SiC2[100]//TiC[101]//MgO[101]. © 2002 American Institute of Physics.
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81.15.Cd Deposition by sputtering
81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.55.-a Thin film structure and morphology

Photonic crystals of shape-anisotropic colloidal particles

Krassimir P. Velikov, Teun van Dillen, Albert Polman, and Alfons van Blaaderen

Appl. Phys. Lett. 81, 838 (2002); http://dx.doi.org/10.1063/1.1497197 (3 pages) | Cited 36 times

Online Publication Date: 22 July 2002

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Spherical silica (SiO2), zinc sulfide (ZnS), and core-shell particles of these materials undergo substantial anisotropic plastic deformation under high-energy ion irradiation. Individual particles can be turned into oblate or prolate ellipsoids with exact control over the aspect ratio. In this letter, we report on the fabrication and optical characterization of thin three-dimensional photonic crystals of spherical particles, which have been anisotropically deformed into spheroidal oblates by means of ion irradiation. As a result of the collective deformation process, both the unit cell symmetry and the particle form factor have been changed leading to appreciable tunability in the optical properties of the photonic crystal. © 2002 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
82.70.Dd Colloids
62.20.F- Deformation and plasticity
61.80.Jh Ion radiation effects

Effect of thickness variation in high-efficiency InGaN/GaN light-emitting diodes

J. Narayan, H. Wang, Jinlin Ye, Schang-Jing Hon, Kenneth Fox, Jyh Chia Chen, H. K. Choi, and John C. C. Fan

Appl. Phys. Lett. 81, 841 (2002); http://dx.doi.org/10.1063/1.1496145 (3 pages) | Cited 13 times

Online Publication Date: 22 July 2002

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InxGa(1−x)N/GaN multiquantum-well light-emitting diodes (LEDs) having periodic thickness variations (TVs) in InxGa(1−x)N active layers exhibit substantially higher optical efficiency than LEDs with uniform InxGa(1−x)N layers. In these nanostructured LEDs, the thickness variation of the active layers is found to be more important than the In composition fluctuation in quantum confinement of excitons (carriers). Detailed scanning transmission electron microscopy-atomic number Z contrast analysis, where image contrast is proportional to Z2 (Z being the atomic number), was carried out to investigate the variation in thickness as well as the spatial distribution of In. In the nanostructured LEDs, there are short-range thickness variations (SR-TVs) (3–4 nm) and long-range thickness variations (LR-TVs) (50–100 nm) in InxGa(1−x)N layers. It is envisaged that LR-TV is key to quantum confinement of the carriers and enhancement of the optical efficiency. We propose that the LR-TV is caused by two-dimensional strain in the InxGa(1−x)N layer below its critical thickness. The SR-TV may be caused by In composition fluctuation. © 2002 American Institute of Physics.
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85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.67.De Quantum wells
68.65.Fg Quantum wells
81.05.Ea III-V semiconductors
73.21.Fg Quantum wells
81.07.St Quantum wells
68.37.Lp Transmission electron microscopy (TEM)
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
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Determination of free hole concentration in ferromagnetic Ga1−xMnxAs using electrochemical capacitance–voltage profiling

K. M. Yu, W. Walukiewicz, T. Wojtowicz, W. L. Lim, X. Liu, Y. Sasaki, M. Dobrowolska, and J. K. Furdyna

Appl. Phys. Lett. 81, 844 (2002); http://dx.doi.org/10.1063/1.1496143 (3 pages) | Cited 30 times

Online Publication Date: 22 July 2002

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We demonstrate that electrochemical capacitance–voltage profiling can be used to determine the free hole concentration in heavily p-type doped low-temperature-grown GaAs films. This provides a simple and reliable method for measuring the hole concentration in ferromagnetic Ga1−xMnxAs semiconductor alloys. The method overcomes the complications that arise from the anomalous Hall effect term which affects standard transport studies of carrier concentration in conducting ferromagnetic materials. Specifically, we find that the maximum Curie temperature of about 111 K found for our Ga0.91Mn0.09As samples corresponds to a hole concentration of 1021 cm−3. © 2002 American Institute of Physics.
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72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
81.05.Ea III-V semiconductors
82.80.Fk Electrochemical methods
75.50.Pp Magnetic semiconductors
75.50.Dd Nonmetallic ferromagnetic materials

Ultrahigh room-temperature hole Hall and effective mobility in Si0.3Ge0.7/Ge/Si0.3Ge0.7 heterostructures

T. Irisawa, S. Tokumitsu, T. Hattori, K. Nakagawa, S. Koh, and Y. Shiraki

Appl. Phys. Lett. 81, 847 (2002); http://dx.doi.org/10.1063/1.1497725 (3 pages) | Cited 36 times

Online Publication Date: 22 July 2002

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We have obtained ultrahigh room-temperature (RT) hole Hall and effective mobility in Si0.3Ge0.7/Ge/Si0.3Ge0.7 heterostructures with very small parallel conduction. Reducing parallel conduction was achieved by employing Sb doping in Si0.3Ge0.7 buffer layers, which drastically increased RT hole Hall mobility up to 2100 cm2/V s in the strained Ge channel modulation-doped structures and improved device characteristics of the p-type metal–oxide–semiconductor field-effect transistors with the strained Ge channel. The peak effective mobility reached to 2700 cm2/V s at RT, which was much higher than the bulk Ge drift mobility. © 2002 American Institute of Physics.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.20.Ee Mobility edges; hopping transport
72.20.Fr Low-field transport and mobility; piezoresistance
85.30.Tv Field effect devices
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.50.Dn Low-field transport and mobility; piezoresistance
85.30.De Semiconductor-device characterization, design, and modeling

Pure-carbon ring transistor: Role of topology and structure

Gianaurelio Cuniberti, Juyeon Yi, and Markus Porto

Appl. Phys. Lett. 81, 850 (2002); http://dx.doi.org/10.1063/1.1497195 (3 pages) | Cited 19 times

Online Publication Date: 22 July 2002

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We report results on the rectification properties of a carbon nanotube (CNT) ring transistor, contacted by CNT leads, whose novel features have been recently communicated by H. Watanabe, C. Manabe, T. Shigematsu, and M. Shimizu [Appl. Phys. Lett. 78, 2928 (2001)]. This letter contains results which are validated by the experimental observations. Moreover, we report on additional features of the transmission of this ring device which are associated with the possibility of breaking the lead inversion symmetry. The linear conductance displays a chessboardlike behavior alternated with anomalous zero lines which should be directly observable in experiments. We are also able to discriminate the structural properties showing up in our results (quasione-dimensional confinement) from pure topological effects (ring configuration), thus helping to gain physical intuition on the rich ring phenomenology. © 2002 American Institute of Physics.
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85.35.Kt Nanotube devices
85.65.+h Molecular electronic devices
81.07.Nb Molecular nanostructures
73.63.Fg Nanotubes
73.40.Ei Rectification
81.07.De Nanotubes

Stress-induced electron emission from nanocomposite amorphous carbon thin films

C. H. Poa, R. G. Lacerda, D. C. Cox, S. R. P. Silva, and F. C. Marques

Appl. Phys. Lett. 81, 853 (2002); http://dx.doi.org/10.1063/1.1497442 (3 pages) | Cited 11 times

Online Publication Date: 22 July 2002

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Traditionally, the emission of electrons from materials have been explained using either the Fowler–Nordheim emission mechanism where high electric fields are used to extract electrons from surfaces or using conventional thermal emission where high currents are used to “boil” off electrons to vacuum. In this letter, we propose an alternative mechanism for electron emission from highly compressive thin films based on stress-induced “band structure” modification of nano-ordered sp2 regions in the thin films. Experimental results are recorded which show that the localized compressive stress governs electron emission in the amorphous carbon thin films studied here rather than the surface nanostructures/features or the diamond-like sp3 hybridized bond component. This analysis is in agreement with the concept of an internal or nongeometric field enhancement from sp2 nanostructures giving rise to high dielectric inhomogeneity within the carbon thin film. The results presented could be extended to explain the anomalous field emission behavior of carbon nanotubes. © 2002 American Institute of Physics.
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79.90.+b Other topics in electron and ion emission by liquids and solids and impact phenomena (restricted to new topics in section 79)

Spatial dependence of ultrafast carrier recombination centers of phosphorus-implanted and annealed silicon wafers

Andreas Othonos and Constantinos Christofides

Appl. Phys. Lett. 81, 856 (2002); http://dx.doi.org/10.1063/1.1497723 (3 pages) | Cited 2 times

Online Publication Date: 22 July 2002

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In this letter, the spatial dependence of the carrier recombination centers induced in phosphorus-implanted and annealed silicon wafers have been examined. Ultrafast time-resolved reflectivity measurements of a set of phosphorus-implanted annealed silicon wafers (1016 P+/cm2) as a function of position on the wafer have been carried out, and an x–y map of the carrier lifetime for each of the samples has been obtained. Measurements reveal distinct features of the distribution of carrier recombination centers for the nonannealed and annealed samples between 350 °C and 1100 °C in an area of 36×36 μm2 with resolution better than 3 μm. The presence of islands of clusters in ion-implanted and annealed samples is also discussed in this letter. © 2002 American Institute of Physics.
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61.72.S- Impurities in crystals
81.05.Cy Elemental semiconductors
61.72.uf Ge and Si
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
71.55.Cn Elemental semiconductors
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
85.40.Ry Impurity doping, diffusion and ion implantation technology
61.72.Cc Kinetics of defect formation and annealing
78.47.-p Spectroscopy of solid state dynamics
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
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Degradation of LaMnO3−y surface layer in LaMnO3−y/metal interface

A. Plecenik, K. Fröhlich, J. P. Espinós, J. P. Holgado, A. Halabica, M. Pripko, and A. Gilabert

Appl. Phys. Lett. 81, 859 (2002); http://dx.doi.org/10.1063/1.1497439 (3 pages) | Cited 16 times

Online Publication Date: 22 July 2002

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We report electrical measurements showing the degradation processes of LaMnO3−y (LaMnO) in LaMnO/normal metal interface in both point contact and planar-type junctions. The time evolution of the junction resistance is characterized by the appearance of a second maximum in the resistance versus temperature dependence (R–T) that occurs at a temperature lower than that for the metal–insulator transition in the bulk. These effects are explained in terms of the formation of a depleted interface layer in LaMnO caused by an out-diffusion of oxygen from the manganite surface to the normal metal. This was confirmed by XPS measurements. Similar results on LaSrMnO3−y/metal interfaces were also obtained. © 2002 American Institute of Physics.
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68.35.Fx Diffusion; interface formation
71.30.+h Metal-insulator transitions and other electronic transitions
73.40.Ns Metal-nonmetal contacts
79.60.Jv Interfaces; heterostructures; nanostructures
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