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5 Nov 2001

Volume 79, Issue 19, pp. 3017-3198

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Photonic band-gap guidance in high-porosity luminescent porous silicon

P. Ferrand, D. Loi, and R. Romestain

Appl. Phys. Lett. 79, 3017 (2001); http://dx.doi.org/10.1063/1.1414302 (3 pages) | Cited 8 times

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We demonstrate a nanoporous silicon (nPS) multilayered structure, offering an efficient photonic band-gap (PBG) single-mode guidance in a high-porosity (i.e., low index) layer in the near-infrared. We show the good agreement between the calculated band structure and the measured spectral range of efficient guiding. We discuss the different kinds of guided modes that exist within the structure, and verify that only one PBG mode can be guided efficiently. Quantitative measurements of the losses are performed using the room-temperature photoluminescence of nPS. © 2001 American Institute of Physics.
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78.55.Ap Elemental semiconductors
78.55.Mb Porous materials
42.70.Qs Photonic bandgap materials
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters

Hybrid optical fiber-apertured cantilever near-field probe

Phan Ngoc Minh, Takahito Ono, Hisashi Watanabe, Seung Soup Lee, Yoichi Haga, and Masayoshi Esashi

Appl. Phys. Lett. 79, 3020 (2001); http://dx.doi.org/10.1063/1.1416475 (3 pages) | Cited 6 times

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In this letter, we propose a hybrid optical fiber-apertured cantilever probe for optical near-field applications. A thermal SiO2 cantilever beam with a SiO2 pyramidal tip was formed by Si micromachining technique and bonded with an optical fiber using a polyimide adhesive layer. A subwavelength aperture at the apex of the SiO2 tip was formed by etching the SiO2 in a buffered-HF solution. Optical near-field imaging in contact mode was observed with the fabricated probe. The probe could work in contact mode because the cantilever at the end of the fiber can flexibly move on the sample surface. By detecting the far-field light which is reflected-back by the tip of the cantilever, the vibration of the cantilever was observed using the probe itself. With the proposed structure, a hybrid fiber bundle-apertured cantilever array is feasible for application in parallel near-field processing or data storage. © 2001 American Institute of Physics.
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07.79.Fc Near-field scanning optical microscopes
42.81.Wg Other fiber-optical devices
07.10.Cm Micromechanical devices and systems
81.20.Wk Machining, milling
07.60.Vg Fiber-optic instruments
81.65.Cf Surface cleaning, etching, patterning

Programmable organic light-emitting devices

C.-C. Wu, C.-W. Chen, Y.-T. Lin, H.-L. Yu, J.-H. Hsu, and T.-Y. Luh

Appl. Phys. Lett. 79, 3023 (2001); http://dx.doi.org/10.1063/1.1414305 (3 pages) | Cited 10 times

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In this letter, we report a promising type of electrically programmable, i.e., reconfigurable, organic light-emitting devices (OLEDs) incorporating a thin carrier-blocking layer as the sacrificial fusing layer. In such devices, the carrier-blocking layer has a lower glass transition temperature than neighboring layers. By raising the internal temperature of the device above the transition temperature of the carrier-blocking layer with a large enough current, interdiffusion between organic layers could occur through such a layer. As a consequence, neighboring layers are fused and a new path for carrier transport is formed, bypassing the carrier-blocking property and altering the device characteristics. A device that emits blue light as fabricated but can be transformed into a green-emitting one is demonstrated. Such a type of device may be used for color pixels in OLED displays, user-programmable OLED applications, and nonvolatile memory devices.© 2001 American Institute of Physics.
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85.60.Jb Light-emitting devices
64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition
68.35.Fx Diffusion; interface formation

Conversion of infrared radiation into red emission in YVO4:Yb,Ho

W. Ryba-Romanowski, S. Golab, G. Dominiak-Dzik, P. Solarz, and T. Lukasiewicz

Appl. Phys. Lett. 79, 3026 (2001); http://dx.doi.org/10.1063/1.1415767 (3 pages) | Cited 18 times

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Upon continuous wave excitation around 1 μm, a YVO4 crystal codoped with ytterbium and holmium exhibits intense red emission originating in the 5F5 level and considerably weaker green emission originating in the 5S2 level of Ho3+. The ratio of the red to green emission intensities is 17:1 at 300 K. The dependence of the intensity of both emissions on the pump power is nearly the same but the mechanisms determined on the basis of short pulse excitation are found to be different. It is concluded that the green emission is excited by two consecutive energy transfers from Yb3+ to Ho3+, whereas excited state absorption is involved in the excitation of red emission. © 2001 American Institute of Physics.  
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
78.40.Ha Other nonmetallic inorganics
78.55.Hx Other solid inorganic materials
78.45.+h Stimulated emission

Optical spectroscopy of GaN microcavities with thicknesses controlled using a plasma etchback

R. W. Martin, P. R. Edwards, H.-S. Kim, K.-S. Kim, T. Kim, I. M. Watson, M. D. Dawson, Y. Cho, T. Sands, and N. W. Cheung

Appl. Phys. Lett. 79, 3029 (2001); http://dx.doi.org/10.1063/1.1415769 (3 pages) | Cited 17 times

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The effect of an etch-back step to control the cavity length within GaN-based microcavities formed between two dielectric Bragg mirrors was investigated using photoluminescence and reflectivity. The structures are fabricated using a combination of a laser lift-off technique to separate epitaxial III-N layers from their sapphire substrates and electron-beam evaporation to deposit silica/zirconia multilayer mirrors. The photoluminescence measurements reveal cavity modes from both etched and nonetched microcavities. Similar cavity finesses are measured for 2.0 and 0.8 μm GaN cavities fabricated from the same wafer, indicating that the etchback has had little effect on the microcavity quality. For InGaN quantum well samples the etchback is shown to allow controllable reduction of the cavity length. Two etch steps of 100 nm are demonstrated with an accuracy of approximately 5%. The etchback, achieved using inductively coupled plasma and wet chemical etching, allows removal of the low-quality GaN nucleation layer, control of the cavity length, and modification of the surface resulting from lift-off. © 2001 American Institute of Physics.
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81.65.Cf Surface cleaning, etching, patterning
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors

Nondegenerate monopole-mode two-dimensional photonic band gap laser

Hong-Gyu Park, Jeong-Ki Hwang, Joon Huh, Han-Youl Ryu, Yong-Hee Lee, and Jeong-Soo Kim

Appl. Phys. Lett. 79, 3032 (2001); http://dx.doi.org/10.1063/1.1416163 (3 pages) | Cited 54 times

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We propose and demonstrate photonic band gap lasing action from a nondegenerate monopole-mode, high-quality factor cavity. By optical pumping at room temperature, the monopole-mode laser is realized and identified from its mode shape, spectrum, and polarization. The monopole-mode laser shows nondegeneracy and genuine two-dimensional oscillation with incident threshold pump power less than 0.3 mW. This laser mode has a small modal volume of ∼ 4.5(λ/2nslab)3 and shows a quality factor of larger than 1900, estimated from the spectral linewidth below threshold. © 2001 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
42.50.Gy Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption
42.55.Rz Doped-insulator lasers and other solid state lasers

Efficient coupling of surface plasmon polaritons to radiation using a bi-grating

P. T. Worthing and W. L. Barnes

Appl. Phys. Lett. 79, 3035 (2001); http://dx.doi.org/10.1063/1.1414294 (3 pages) | Cited 48 times

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A nanostructured surface in the form of a bi-grating is shown to efficiently couple surface plasmon polaritons to free-space radiation in the visible part of the spectrum. Coupling was achieved for all propagation directions of the surface mode and the efficiency found to be independent of the propagation direction, taking a mean value of 60% for the structure examined. The consequences of the findings for emissive devices that make use of surface plasmons are discussed. © 2001 American Institute of Physics.
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73.22.Lp Collective excitations
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
42.79.Dj Gratings
78.40.-q Absorption and reflection spectra: visible and ultraviolet

Thermal characteristics of optical gain for GaInNAs quantum wells at 1.3 μm

Chang Kyu Kim and Yong Hee Lee

Appl. Phys. Lett. 79, 3038 (2001); http://dx.doi.org/10.1063/1.1418022 (3 pages) | Cited 16 times

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The gain characteristics of 1.3-μm-wavelength GaInNAs, InGaAlAs, and InGaAsP single-quantum-well structures are studied and compared. Among these quantum wells, GaInNAs offers the lowest carrier density over a wide range of temperature (300–400 K) for applications that require high gain because of the highest differential gain. It is due to the large electron effective mass originating from the nitrogen incorporation. The change in threshold carrier density with temperature is smallest for GaInNAs because of the large conduction band offset and the large differences in the band gap energy between the well and the barrier. The interaction with the temperature-independent nitrogen states makes the shift of gain with temperature slowest as well. For these reasons, the threshold current of GaInNAs is expected to be more temperature independent than those of other materials.© 2001 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.67.De Quantum wells
73.21.Fg Quantum wells
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Measurement of ion temperatures in a large-diameter electron cyclotron resonance plasma

Mayuko Koga, Takenori Yoshizawa, Yoko Ueda, Yoshinobu Kawai, and Akira Yonesu

Appl. Phys. Lett. 79, 3041 (2001); http://dx.doi.org/10.1063/1.1416154 (3 pages) | Cited 7 times

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The ion temperature in a large-diameter electron cyclotron resonance plasma is measured using high-resolution optical emission spectroscopy, and the correlation between the ion temperature and fluctuations observed near the chamber wall is investigated. Furthermore, the effect of multicusped fields on the ion temperature is examined. The ion temperature and the amplitude of ion saturation current fluctuations are found to decrease when multicusped fields are applied. The ion temperature and fluctuations increase with increasing incident microwave powers from 2.0 to 2.5 kW, indicating that the ion temperature is correlated with the fluctuation amplitude. The measurement of the ion saturation current fluctuation and floating potential fluctuation suggests that the fluctuations are excited by flute instability. © 2001 American Institute of Physics.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.-b Plasma properties
52.35.Py Macroinstabilities (hydromagnetic, e.g., kink, fire-hose, mirror, ballooning, tearing, trapped-particle, flute, Rayleigh-Taylor, etc.)
52.50.Sw Plasma heating by microwaves; ECR, LH, collisional heating
52.25.Gj Fluctuation and chaos phenomena

Quasi-direct current plasma immersion ion implantation

Xuchu Zeng, Ricky K. Y. Fu, Dixon T. K. Kwok, and Paul K. Chu

Appl. Phys. Lett. 79, 3044 (2001); http://dx.doi.org/10.1063/1.1415404 (3 pages) | Cited 9 times

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Quasi-dc (direct current) plasma immersion ion implantation (PIII) is demonstrated in the long-pulse mode. To prevent plasma extinction as a result of the sheath reaching the vacuum chamber wall in long-pulse experiments, a grounded grid is used to partition the chamber into two halves. The pulse width can be readily increased to 500 μs that is more than 10 times longer than that in typical low-pressure PIII experiments for monoenergetic implantation (ion mean free path≫sheath thickness). The electron saturation current measured by the Langmuir probe indicates that the grounded grid indeed stops the propagation of the plasma sheath. After the plasma sheath reaches the grounded grid, the pulse current drops to a smaller value indicative of the quasi-dc PIII mode. The plasma recovery time is found to be 800 μs thereby limiting the maximum pulsing frequency to below 1 kHz, and the preferred pulse duration window is between 100 and 500 μs. The secondary ion mass spectrometry profiles show that low energy ions are reduced using long pulses. This operation mode thus offers the unique advantage of a smaller low-energy ion component, that is, more monoenergetic ion distribution, and less surface damage compared to conventional short-pulse PIII. When compared to dc-PIII, this mode retains the discharge characteristics and works well for insulators. © 2001 American Institute of Physics.
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52.77.Dq Plasma-based ion implantation and deposition
61.72.up Other materials
52.40.Kh Plasma sheaths
52.70.Ds Electric and magnetic measurements
52.70.Nc Particle measurements
85.40.Ry Impurity doping, diffusion and ion implantation technology
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Green emission from cerium hydroxide layers formed in Si/In/CeO2/Si structures

Chong-Geol Kim

Appl. Phys. Lett. 79, 3047 (2001); http://dx.doi.org/10.1063/1.1416161 (3 pages) | Cited 5 times

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Green photoluminescence (PL) was observed from the Si/In/CeO2 on Si substrates at room temperature. Indium was very thinly deposited on CeO2 at 400 °C. X-ray photoelectron spectroscopy indicated the formation of a cerium hydroxide in the indium-included Si/CeO2 structure. The reacting CeO2 with In became the defective CeO2−x, and then the defective CeO2−x was changed to Ce(OH)4 in poor vacuums and air. The green PL was due to Ce(OH)4. The luminescence disappeared by high-temperature annealing. Another PL peak appeared from the sample annealed at 1000 °C. © 2001 American Institute of Physics.
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78.66.Nk Insulators
61.72.Cc Kinetics of defect formation and annealing
79.60.Jv Interfaces; heterostructures; nanostructures
78.55.Hx Other solid inorganic materials

Micromodification of silicon dioxide in a variable pressure/environmental scanning electron microscope

Marion A. Stevens-Kalceff

Appl. Phys. Lett. 79, 3050 (2001); http://dx.doi.org/10.1063/1.1415773 (3 pages) | Cited 8 times

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Electron irradiation in the ionized gaseous environment of a variable pressure/environmental scanning electron microscope induces modifications of poorly conducting specimens. In particular it is shown, using nondestructive depth-resolved cathodoluminescence microanalysis, that environmental ions can penetrate into the bulk of the irradiated specimen and modify the local microstructure of the irradiated specimen. The observed modifications are attributed to electric fields associated with trapped electrons and environmental ions. These effects can be controlled by varying the environmental gas and/or electron beam parameters. © 2001 American Institute of Physics.
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61.80.Fe Electron and positron radiation effects
78.60.Hk Cathodoluminescence, ionoluminescence
68.35.B- Structure of clean surfaces (and surface reconstruction)

Superhard, conductive coatings for atomic force microscopy cantilevers

C. Ronning, O. Wondratschek, M. Büttner, H. Hofsäss, J. Zimmermann, P. Leiderer, and J. Boneberg

Appl. Phys. Lett. 79, 3053 (2001); http://dx.doi.org/10.1063/1.1415354 (3 pages) | Cited 3 times

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Boron carbide thin films were grown by mass selected ion beam deposition using low energy 11B+ and 12C+ ions at room temperature. The amorphous films exhibit any desired stoichiometry controlled by the ion charge ratio B+/C+. Films with a stoichiometry of B4C showed the optimal combination of a high mechanical strength and a low electrical resistivity for the coating of atomic force microscopy (AFM) silicon cantilevers. The properties of such AFM tips were evaluated and simultaneous topography and Kelvin mode AFM measurements with high lateral resolution were performed on the systems (i) Au nanoparticles on a p-WS2 surface and (ii) conducting/superconducting YBa2Cu3O7−x. © 2001 American Institute of Physics.
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07.79.Lh Atomic force microscopes
68.37.Ps Atomic force microscopy (AFM)
81.15.Jj Ion and electron beam-assisted deposition; ion plating
68.60.Bs Mechanical and acoustical properties
68.55.A- Nucleation and growth
68.55.Nq Composition and phase identification

Observation of 4H–SiC to 3C–SiC polytypic transformation during oxidation

Robert S. Okojie, Ming Xhang, Pirouz Pirouz, Sergey Tumakha, Gregg Jessen, and Leonard J. Brillson

Appl. Phys. Lett. 79, 3056 (2001); http://dx.doi.org/10.1063/1.1415347 (3 pages) | Cited 55 times

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We have observed the formation of single and multiple stacking faults that sometimes give rise to 3C–SiC bands in a highly doped n-type 4H–SiC epilayer following dry thermal oxidation. Transmission electron microscopy following oxidation revealed single stacking faults and bands of 3C–SiC in a 4H–SiC matrix within the 4H–SiC epilayer. These bands, parallel to the (0001) basal plane, were not detected in unoxidized control samples. In addition to the 3.22 eV peak of 4H–SiC, Cathodoluminescence spectroscopy at 300 K after oxidation revealed a spectral peak at 2.5 eV photon energy that was not present in the sample prior to oxidation. The polytypic transformation is tentatively attributed to the motion of Shockley partial dislocations on parallel (0001) slip planes. The generation and motion of these partials may have been induced by stresses caused either by the heavy doping of the epilayer or nucleation from defect. © 2001 American Institute of Physics.
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81.65.Mq Oxidation
61.72.Nn Stacking faults and other planar or extended defects
64.70.K- Solid-solid transitions
81.05.Hd Other semiconductors
78.60.Hk Cathodoluminescence, ionoluminescence
62.20.-x Mechanical properties of solids
61.72.Lk Linear defects: dislocations, disclinations

Effect of Sb as a surfactant during the lateral epitaxial overgrowth of GaN by metalorganic vapor phase epitaxy

L. Zhang, H. F. Tang, and T. F. Kuech

Appl. Phys. Lett. 79, 3059 (2001); http://dx.doi.org/10.1063/1.1415774 (3 pages) | Cited 14 times

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Antimony (Sb), an isoelectronic impurity, has been studied as a surfactant during the lateral epitaxial overgrowth (LEO) of gallium nitride (GaN) by metalorganic vapor phase epitaxy (MOVPE). The presence of Sb in the gas phase was found to alter both the LEO growth rates and the predominant facet formations. Vertical facets to the LEO growth appear with the addition of Sb under conditions that normally produce triangular or sloped sidewalls over a range of growth temperatures. While Sb alters the growth facets, only a small amount of Sb was incorporated into the GaN, suggesting that Sb acts as a surfactant during the GaN MOVPE growth. Sb addition produces surface conditions characteristic of a Ga-rich surface stoichiometry indicating both a possible change in the reactivity of NH3 and/or enhanced surface diffusion of Ga adatom species. © 2001 American Institute of Physics.
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81.05.Ea III-V semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Metalorganic vapor phase epitaxy growth of crack-free AlN on GaN and its application to high-mobility AlN/GaN superlattices

Shigeo Yamaguchi, Masayoshi Kosaki, Yasuyukihiro Watanabe, Yohei Yukawa, Shugo Nitta, Hiroshi Amano, and Isamu Akasaki

Appl. Phys. Lett. 79, 3062 (2001); http://dx.doi.org/10.1063/1.1416169 (3 pages) | Cited 12 times

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We have succeeded in growing crack-free AlN of even 0.5 μm thickness on GaN by metalorganic vapor phase epitaxy. A (0001) sapphire substrate was used. Crack-free AlN was grown on GaN at 1000 °C with N2 carrier gas. An AlN layer was grown on GaN of 2 μm thickness grown at 1050 °C, following the low-temperature deposition of an AlN buffer layer of 30 nm. No cracks were observed in the microphotographs of AlN on GaN grown using N2. X-ray diffraction analysis revealed that AlN/GaN superlattices (SLs) were coherently grown on GaN, and satellite peaks up to the third order were observed. The structure of AlN/GaN SLs on GaN showed a maximum electron mobility of 1580 cm2/V s at room temperature and a nominal sheet carrier density of 8.4×1012 cm−2. © 2001 American Institute of Physics.
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68.65.Cd Superlattices
81.05.Ea III-V semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase
73.61.Ey III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
73.50.Dn Low-field transport and mobility; piezoresistance

Enabling electron diffraction as a tool for determining substrate temperature and surface morphology

V. P. LaBella, D. W. Bullock, C. Emery, Z. Ding, and P. M. Thibado

Appl. Phys. Lett. 79, 3065 (2001); http://dx.doi.org/10.1063/1.1416477 (3 pages) | Cited 12 times

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The reconstruction transitions for the GaAs(001) surface have been identified as a function of the band gap-derived substrate temperature and As4 beam equivalent pressure. Surface morphology measurements using in situ scanning tunneling microscopy reveal that the surface spontaneously forms a random distribution of two-dimensional islands. The onset of island formation is coincident with the reflected high-energy electron diffraction pattern changing from the β to α subphase of the (2×4) reconstruction. An electron diffraction-based method for determining the substrate temperature and engineering the surface morphology with a desired amount of roughness is presented. © 2001 American Institute of Physics.
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61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)
68.35.B- Structure of clean surfaces (and surface reconstruction)

Lattice location of phosphorus in n-type homoepitaxial diamond films grown by chemical-vapor deposition

Masataka Hasegawa, Tokuyuki Teraji, and Satoshi Koizumi

Appl. Phys. Lett. 79, 3068 (2001); http://dx.doi.org/10.1063/1.1417514 (3 pages) | Cited 20 times

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The lattice location of phosphorus dopant atoms in n-type homoepitaxial diamond {111} films grown by chemical-vapor deposition has been investigated by Rutherford backscattering spectrometry and particle-induced x-ray emission under ion-channeling conditions. It is found that phosphorus dopant atoms occupy the substitutional sites almost completely in the host diamond lattice. The substitutional fraction of phosphorus was more than 0.9 for 〈011〉 and 〈111〉 directions. Present observation implies that the deep ground-state energy level of phosphorus in diamond, which is at 0.6 eV below the bottom of the conduction band, is attributed to the relaxation of surrounding carbon atoms. © 2001 American Institute of Physics.
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61.72.S- Impurities in crystals
61.85.+p Channeling phenomena (blocking, energy loss, etc.)
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis
71.55.Cn Elemental semiconductors
61.72.up Other materials

Three-dimensional phase field microelasticity theory and modeling of multiple cracks and voids

Y. M. Jin, Y. U. Wang, and A. G. Khachaturyan

Appl. Phys. Lett. 79, 3071 (2001); http://dx.doi.org/10.1063/1.1418260 (3 pages) | Cited 15 times

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It is proved that the stress-free strain distribution minimizing the strain energy of the homogeneous modulus body fully determines the elasticity of the discontinuous body. This result is used as a basis for the proposed three-dimensional phase field microelasticity theory and model of a discontinuous body with cracks and voids in elastically anisotropic crystal under applied stress. The elastic equilibrium and spontaneous evolution of these defects are described by the Ginzburg–Landau kinetic equation. Examples of computations of elastic equilibrium and evolutions of systems with cracks and/or voids are considered. © 2001 American Institute of Physics.
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46.25.Cc Theoretical studies
62.20.D- Elasticity
46.50.+a Fracture mechanics, fatigue and cracks
62.20.M- Structural failure of materials
61.72.Qq Microscopic defects (voids, inclusions, etc.)
61.72.Bb Theories and models of crystal defects
46.15.Cc Variational and optimizational methods

Electrical characterization of 1.8 MeV proton-bombarded ZnO

F. D. Auret, S. A. Goodman, M. Hayes, M. J. Legodi, H. A. van Laarhoven, and D. C. Look

Appl. Phys. Lett. 79, 3074 (2001); http://dx.doi.org/10.1063/1.1415050 (3 pages) | Cited 131 times

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We report on the electrical characterization of single-crystal ZnO and Au Schottky contacts formed thereon before and after bombarding them with 1.8 MeV protons. From capacitance–voltage measurements, we found that ZnO is remarkably resistant to high-energy proton bombardment and that each incident proton removes about two orders of magnitude less carriers than in GaN. Deep level transient spectroscopy indicates a similar effect: the two electron traps detected are introduced in extremely low rates. One possible interpretation of these results is that the primary radiation-induced defects in ZnO may be unstable at room temperature and anneal out without leaving harmful defects that are responsible for carrier compensation. © 2001 American Institute of Physics.
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71.55.Gs II-VI semiconductors
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
73.30.+y Surface double layers, Schottky barriers, and work functions
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Reflection high-energy electron diffraction studies of epitaxial oxide seed-layer growth on rolling-assisted biaxially textured substrate Ni(001): The role of surface structure and chemistry

C. Cantoni, D. K. Christen, R. Feenstra, A. Goyal, G. W. Ownby, D. M. Zehner, and D. P. Norton

Appl. Phys. Lett. 79, 3077 (2001); http://dx.doi.org/10.1063/1.1407857 (3 pages) | Cited 21 times

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We present a study of the {100}〈100〉 biaxially textured Ni(001) surface and seed-layer growth using in situ reflection high-energy electron diffraction and Auger electron spectroscopy. Our observations are consistent with formation of a c(2×2) two-dimensional superstructure due to the surface segregation of sulfur contained in the metal. We show that this superstructure can have a dramatic effect on the heteroepitaxial growth of oxide seed layers. In particular, the surface superstructure promotes the (200) epitaxial oxide growth of Y2O3-stabilized ZrO2, which is necessary for the development of high-Jc superconducting films for coated conductors. © 2001 American Institute of Physics.
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68.35.B- Structure of clean surfaces (and surface reconstruction)
68.35.Dv Composition, segregation; defects and impurities
68.55.-a Thin film structure and morphology
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Fingerprints of two distinct defects causing light-induced photoconductivity degradation in hydrogenated amorphous silicon

Stephan Heck and Howard M. Branz

Appl. Phys. Lett. 79, 3080 (2001); http://dx.doi.org/10.1063/1.1413719 (3 pages) | Cited 7 times

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We find distinct experimental fingerprints of two metastable defects created during illumination of hydrogenated amorphous silicon. The well-studied threefold-coordinated silicon dangling bond defect has an anneal activation energy near 1.1 eV and dominates annealing experiments above about 110 °C. The second defect created by illumination is the “primary recombination” (pr) center, which causes most of the light-induced photoconductivity decrease and dominates annealing experiments below about 110 °C. Because the pr centers are created in linear proportion to the dangling bond defects, they are difficult to distinguish during degradation. However, we observe clear fingerprints of the pr center during their low T annealing: (1) an anneal activation energy of 0.85 eV; (2) a sharp increase in photoconductivity; and (3) a surprising increase in hν ⩽ 1.1 eV optical absorption. © 2001 American Institute of Physics.
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73.50.Pz Photoconduction and photovoltaic effects
71.55.Jv Disordered structures; amorphous and glassy solids
73.61.Jc Amorphous semiconductors; glasses
61.43.Dq Amorphous semiconductors, metals, and alloys
73.61.Cw Elemental semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Growth of well-aligned carbon nanotube arrays on silicon substrates using porous alumina film as a nanotemplate

Wenchong Hu, Dawei Gong, Zhi Chen, Liming Yuan, Kozo Saito, Craig A. Grimes, and Padmakar Kichambare

Appl. Phys. Lett. 79, 3083 (2001); http://dx.doi.org/10.1063/1.1415406 (3 pages) | Cited 52 times

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Aligned, open-tipped carbon nanotube arrays of high density and uniformity were synthesized via a flame method on silicon substrates using a nanoporous template of anodized aluminum oxide from which the nanotubes were grown. The diameter and length of the nanotubes are controlled by the geometry of the aluminum oxide template. These results show the feasibility of integration between carbon nanotube arrays and silicon microelectronics. © 2001 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
81.07.De Nanotubes
85.35.Kt Nanotube devices
81.16.Be Chemical synthesis methods
85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology

Carrier density imaging of lateral epitaxially overgrown GaN using scanning confocal Raman microscopy

Manyalibo J. Matthews, J. W. P. Hsu, Shulin Gu, and T. F. Kuech

Appl. Phys. Lett. 79, 3086 (2001); http://dx.doi.org/10.1063/1.1415421 (3 pages) | Cited 7 times

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GaN thin films, grown by the lateral epitaxial overgrowth (LEO) method, are studied by scanning confocal Raman microscopy. By measuring changes in coupled longitudinal-optical phonon–plasmon frequencies and using a standard harmonic oscillator dielectric function, detailed images of carrier density could be formed. Carrier concentrations are extremely high ( ∼ 1020 cm−3) immediately above SiOx mask layers and decrease abruptly when the SiOx mask are not directly exposed to the growth surface, implying that SiOx masks are the source of dopants. Images of intergrated E1 longitudinal-optical phonon intensities could be compared with free-carrier images and showed a clear anticorrelation throughout the LEO structure.© 2001 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.30.Fs III-V and II-VI semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.61.Ey III-V semiconductors
81.05.Ea III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
63.20.kk Phonon interactions with other quasiparticles

Formation of nonradiative defects in molecular beam epitaxial GaNxAs1−x studied by optically detected magnetic resonance

N. Q. Thinh, I. A. Buyanova, W. M. Chen, H. P. Xin, and C. W. Tu

Appl. Phys. Lett. 79, 3089 (2001); http://dx.doi.org/10.1063/1.1416155 (3 pages) | Cited 36 times

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The formation of two nonradiative defects (i.e., an AsGa-related complex and an unknown deep-level defect with g = 2.03) in GaNxAs1−x epilayers and GaAs/GaNxAs1−x multiple-quantum-well structures, grown by molecular beam epitaxy, is studied by the optically detected magnetic resonance technique. It is shown that contributions by these defects in competing carrier recombination strongly vary with the nitrogen composition. An increase in the growth temperature or postgrowth rapid thermal annealing significantly reduces the influence of the nonradiative defects studied, and is accompanied by a remarkable improvement in the optical properties of the structures. © 2001 American Institute of Physics.
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76.70.Hb Optically detected magnetic resonance (ODMR)
73.20.Hb Impurity and defect levels; energy states of adsorbed species
71.55.Eq III-V semiconductors
73.21.Fg Quantum wells
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.72.Cc Kinetics of defect formation and annealing
61.82.Fk Semiconductors
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