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28 May 2001

Volume 78, Issue 22, pp. 3379-3553

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High-power AlGaInN flip-chip light-emitting diodes

J. J. Wierer, D. A. Steigerwald, M. R. Krames, J. J. O’Shea, M. J. Ludowise, G. Christenson, Y.-C. Shen, C. Lowery, P. S. Martin, S. Subramanya, W. Götz, N. F. Gardner, R. S. Kern, and S. A. Stockman

Appl. Phys. Lett. 78, 3379 (2001); http://dx.doi.org/10.1063/1.1374499 (3 pages) | Cited 162 times

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Data are presented on high-power AlGaInN flip-chip light-emitting diodes (FCLEDs). The FCLED is “flipped-over” or inverted compared to conventional AlGaInN light-emitting diodes (LEDs), and light is extracted through the transparent sapphire substrate. This avoids light absorption from the semitransparent metal contact in conventional epitaxial-up designs. The power FCLED has a large emitting area ( ∼ 0.70 mm2) and an optimized contacting scheme allowing high current (200–1000 mA, J ∼ 30–143 A/cm2) operation with low forward voltages ( ∼ 2.8 V at 200 mA), and therefore higher power conversion (“wall-plug”) efficiencies. The improved extraction efficiency of the FCLED provides 1.6 times more light compared to top-emitting power LEDs and ten times more light than conventional small-area ( ∼ 0.07 mm2) LEDs. FCLEDs in the blue wavelength regime ( ∼ 435 nm peak) exhibit ∼ 21% external quantum efficiency and ∼ 20% wall-plug efficiency at 200 mA and with record light output powers of 400 mW at 1.0 A. © 2001 American Institute of Physics.
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85.60.Jb Light-emitting devices
85.60.Bt Optoelectronic device characterization, design, and modeling
42.72.Bj Visible and ultraviolet sources
78.66.Fd III-V semiconductors

Potential applications of dark resonance to subpicosecond optical switches in hyper-terahertz repetition rates

Byoung S. Ham

Appl. Phys. Lett. 78, 3382 (2001); http://dx.doi.org/10.1063/1.1374227 (3 pages) | Cited 20 times

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Subpicosecond optical switching in hyper-terahertz repetition rates is numerically demonstrated using dark resonance based two-photon coherence swapping. The switching time and repetition rate demonstrated are one tenth the population relaxation time T1, and it is a breakthrough in the critical limitation of current technologies of optical switches. This demonstration implies potential applications of ultrafast optical switches to ultrahigh-capacity fiber-optic communications. © 2001 American Institute of Physics.
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42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.50.Hz Strong-field excitation of optical transitions in quantum systems; multiphoton processes; dynamic Stark shift

Biexciton emission from ZnO/Zn0.74Mg0.26O multiquantum wells

H. D. Sun, T. Makino, Y. Segawa, M. Kawasaki, A. Ohtomo, K. Tamura, and H. Koinuma

Appl. Phys. Lett. 78, 3385 (2001); http://dx.doi.org/10.1063/1.1375830 (3 pages) | Cited 35 times

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Luminescence due to the radiative recombination of localized biexcitons has been observed at low temperature (5 K) in ZnO/Zn0.74Mg0.26O multiquantum wells grown by laser-molecular-beam epilaxy on a lattice-matched ScAlMgO4 substrate (0001). The emission components due to the recombination of localized excitons and biexcitons and due to the exciton–exciton scattering were verified by examining their relative energy positions and intensity dependence on excitation power density. The excitation threshold for biexciton emission was significantly lower than that for exciton–exciton scattering. The binding energy of biexcitons in multi-quantum wells is largely enhanced by quantum confinement effect. © 2001 American Institute of Physics.
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78.66.Hf II-VI semiconductors
78.55.Et II-VI semiconductors
78.67.De Quantum wells
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.35.Lk Collective effects (Bose effects, phase space filling, and excitonic phase transitions)

Multipole-cancellation mechanism for high-Q cavities in the absence of a complete photonic band gap

Steven G. Johnson, Shanhui Fan, Attila Mekis, and J. D. Joannopoulos

Appl. Phys. Lett. 78, 3388 (2001); http://dx.doi.org/10.1063/1.1375838 (3 pages) | Cited 51 times

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We describe and demonstrate a new mechanism for low radiation losses in structures lacking a complete band gap, and show how resonant cavities with Q>103 can be achieved without sacrificing strong localization in 3d. This involves a forced cancellation in the lowest-order term(s) of the multipole far-field radiation expansion. We focus on the system of photonic-crystal slabs, one- to two-dimensionally periodic dielectric structures of finite height with vertical index guiding. Simulations and analytical results in 2d and 3d are presented. © 2001 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
42.50.-p Quantum optics

Temperature dependence of laser threshold in an InGaAsN vertical-cavity surface-emitting laser

H. C. Schneider, A. J. Fischer, W. W. Chow, and J. F. Klem

Appl. Phys. Lett. 78, 3391 (2001); http://dx.doi.org/10.1063/1.1374484 (3 pages) | Cited 14 times

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We present theoretical and experimental results for the temperature dependence of threshold current in an InGaAsN/GaAs vertical-cavity surface-emitting laser (VCSEL) operating at 1.3 μm under continuous-wave current injection. Using a microscopic many-body laser theory, good agreement with experimental data is obtained. The influence of radiative and nonradiative recombination processes on the threshold current–density is investigated theoretically. Also, comparison to a GaAs/AlGaAs VCSEL emitting at 850 nm is made. © 2001 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Virtual mesa and spoiler midinfrared angled-grating distributed feedback lasers fabricated by ion bombardment

R. E. Bartolo, W. W. Bewley, C. L. Felix, I. Vurgaftman, J. R. Lindle, J. R. Meyer, D. L. Knies, K. S. Grabowski, G. W. Turner, and M. J. Manfra

Appl. Phys. Lett. 78, 3394 (2001); http://dx.doi.org/10.1063/1.1377044 (3 pages) | Cited 4 times

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It is demonstrated that the suppression of parasitic Fabry–Perot-like lasing modes substantially enhances the beam quality and brightness of wide-stripe angled-grating distributed feedback lasers emitting in the midwave infrared. The direct facet-to-facet gain path is blocked by loss regions that are created by ion bombardment with 900 keV silicon ions. Both virtual mesa structures, in which loss regions bound both sides of the 300-μm-wide angled gain path, and spoiler structures, in which loss is induced only near the facets, decrease the etendue of the output by nearly an order of magnitude, and increase the brightness by up to a factor of 3. © 2001 American Institute of Physics.
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42.60.By Design of specific laser systems
42.55.Px Semiconductor lasers; laser diodes
42.79.Dj Gratings
42.86.+b Optical workshop techniques
61.82.Fk Semiconductors
61.80.Jh Ion radiation effects

Ultrafast dynamics of InAs/GaAs quantum-dot microdisk lasers

K. J. Luo, J. Y. Xu, H. Cao, Y. Ma, S. H. Chang, S. T. Ho, and G. S. Solomon

Appl. Phys. Lett. 78, 3397 (2001); http://dx.doi.org/10.1063/1.1376437 (3 pages) | Cited 14 times

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The dynamical response of InAs/GaAs quantum-dot microdisk lasers has been experimentally investigated using femtosecond optical pumping. Because surface recombination and carrier diffusion are suppressed in the quantum dots, the response speed of a quantum-dot microdisk laser is much faster than that of a quantum-well microdisk laser. A turn-on time as short as 7.8 ps has been achieved in a quantum-dot microdisk laser at 5 K. The temperature dependence of the dynamical response of the quantum-dot microdisk lasers has also been studied over a wide temperature range. At the same pumping level, the turn-on time of the laser decreases as the temperature increases from 5 to 120 K. Such behavior may be due to a faster carrier relaxation process at higher temperature. © 2001 American Institute of Physics.
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42.55.Sa Microcavity and microdisk lasers
78.67.Hc Quantum dots
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
78.47.-p Spectroscopy of solid state dynamics

Two-dimensional photonic crystals: Candidate for wave plates

Lie-Ming Li

Appl. Phys. Lett. 78, 3400 (2001); http://dx.doi.org/10.1063/1.1375839 (3 pages) | Cited 16 times

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We have numerically investigated the optical paths of S and P waves propagating through two-dimensional photonic crystals consisting of dielectric cylinders parallel to each other, where S waves and P waves specify electromagnetic waves with the electric field parallel to the cylinders and electromagnetic waves with the electric field perpendicular to the cylinders, respectively. It is found that the difference between the optical paths of S and P waves can be many times the path difference in the case of a conventional wave plate with the same thickness. Therefore, we propose that two-dimensional photonic crystals can be employed as thin wave plates that can be used as integrated optical and microwave components. © 2001 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
42.25.Bs Wave propagation, transmission and absorption
42.82.Gw Other integrated-optical elements and systems
42.79.Ci Filters, zone plates, and polarizers
84.40.-x Radiowave and microwave (including millimeter wave) technology

Ultrasonic monitoring of laser damage in fused silica

Louis P. Martin, Mary A. Norton, and Graham Thomas

Appl. Phys. Lett. 78, 3403 (2001); http://dx.doi.org/10.1063/1.1376431 (3 pages) | Cited 1 time

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The growth of a laser induced, surface damage site in a fused silica window was monitored by the ultrasonic pulse-echo technique. The laser damage was grown using 15 ns pulses of 1.053 μm wavelength light at a fluence of ∼25 J/cm2. The ultrasonic signal amplitude exhibited variations with the damage size which are attributable to the changing subsurface morphology of the damage site. The sensitivity to subsurface morphology makes the ultrasonic methodology a promising tool for monitoring laser damage in fused silica optics. This type of diagnostic capability may facilitate the safe deployment of large, high powered laser systems used in high energy and fusion research facilities. © 2001 American Institute of Physics.
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42.70.Ce Glasses, quartz
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.-d Radiation effects on specific materials
43.35.Yb Ultrasonic instrumentation and measurement techniques
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Microcavity-enhanced surface-emitted second-harmonic generation from 200 fs pulses at 1.5 μm

Todd G. Ulmer, Marc Hanna, Brian R. Washburn, Carl M. Verber, Stephen E. Ralph, and Anthony J. SpringThorpe

Appl. Phys. Lett. 78, 3406 (2001); http://dx.doi.org/10.1063/1.1376429 (3 pages) | Cited 1 time

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We present theoretical results for short-pulse surface-emitted second-harmonic generation and show that significant cavity enhancement is possible in the femtosecond regime. Experimentally, we demonstrate enhanced surface-emitted second-harmonic generation using 200 fs fundamental pulses near 1.5 μm by use of a 5λSH/2n vertical microcavity in [211]-oriented AlGaAs waveguides. The microcavity height is minimized by allowing the distributed Bragg reflectors that define the vertical cavity to also serve as cladding layers for the fundamental waveguide, thereby increasing the resonance width and hence the overlap with the second-harmonic spectrum. © 2001 American Institute of Physics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.65.Wi Nonlinear waveguides
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.79.Gn Optical waveguides and couplers
42.79.Nv Optical frequency converters

Recovery dynamics in proton-bombarded semiconductor saturable absorber mirrors

Juliet T. Gopinath, Erik R. Thoen, Elisabeth M. Koontz, Matthew E. Grein, Leslie A. Kolodziejski, Erich P. Ippen, and Joseph P. Donnelly

Appl. Phys. Lett. 78, 3409 (2001); http://dx.doi.org/10.1063/1.1376663 (3 pages) | Cited 9 times

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Reduction of device response time, resulting from the proton bombardment of InGaAs/InP-based semiconductor saturable absorbers, was studied experimentally using an ultrafast degenerate, cross- polarized pump-probe technique. Proton bombardment is shown to reduce device response times to ∼1 ps at low optical excitation densities. Under high excitation, the device dynamics are dominated by induced absorption. The extended recovery of highly excited carriers appears to be less sensitive to defects created by bombardment. Mode locking was demonstrated with the proton-bombarded samples in an erbium-doped fiber laser. © 2001 American Institute of Physics.
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42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
42.79.Bh Lenses, prisms and mirrors
61.82.Fk Semiconductors
61.80.Jh Ion radiation effects
42.60.Fc Modulation, tuning, and mode locking

Investigation of indium tin oxide/zinc oxide multilayer ohmic contacts to n-type GaN isotype conjunction

Ching-Ting Lee, Qing-Xuan Yu, Bang-Tai Tang, Hsin-Ying Lee, and Fu-Tsai Hwang

Appl. Phys. Lett. 78, 3412 (2001); http://dx.doi.org/10.1063/1.1376430 (3 pages) | Cited 18 times

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The ohmic performance of the ITO/ZnO multilayer deposited on n-type GaN layer was investigated. The best thermal annealing condition achieved for ohmic contact was 5 min at 500 °C, in hydrogen ambient. The measured specific contact resistance was 3×10−4 Ω cm2. Ohmic formation mechanisms would be attributed to the ITO/n-ZnO/n-GaN isotype conjunction and the reduction conduction band offset due to the quantum confinement effects in the thin ZnO layer. © 2001 American Institute of Physics.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
61.72.Cc Kinetics of defect formation and annealing
73.20.At Surface states, band structure, electron density of states
73.21.Cd Superlattices

High-sensitivity absorption measurement in water and glass samples using a mode-mismatched pump-probe thermal lens method

A. Marcano O., C. Loper, and N. Melikechi

Appl. Phys. Lett. 78, 3415 (2001); http://dx.doi.org/10.1063/1.1375835 (3 pages) | Cited 26 times

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We report on a mode-mismatched pump-probe thermal lens experiment performed to measure absorption coefficients as small as 10−8 cm−1 in liquid and solid samples. We take advantage of the large axial dimension of the thermal lens by focusing the pump beam in the presence of a collimated probe beam. We measure an absorption coefficient at 533 nm of (6.8±0.1)×10−4 cm−1 and of (3±0.3)×10−6 cm−1 for distilled water and BK7 optical glass, respectively. © 2001 American Institute of Physics.
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07.60.Rd Visible and ultraviolet spectrometers
78.20.N- Thermo-optic effects
78.20.nb Photothermal effects
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.70.Ce Glasses, quartz
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Low-voltage electron emission from “tipless” field emitter arrays

H. Busta, D. Furst, A. T. Rakhimov, V. A. Samorodov, B. V. Seleznev, N. V. Suetin, and A. Silzars

Appl. Phys. Lett. 78, 3418 (2001); http://dx.doi.org/10.1063/1.1376153 (3 pages) | Cited 9 times

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Electron emission is obtained from “tipless” gated n-silicon arrays (6460 gate holes) by depositing about 10 nm of nanocrystalline graphite (NCG) on top of the gates and into the gate holes by a glow-discharge technique at 900 °C. The polycrystalline silicon gate diameter is 1.8 μm and the gate-to-substrate distance is 0.85 μm. The interdielectric layer is SiO2. Turn-on voltages are about 40–60 V. The gate currents are about 50% of the total emission currents. From the emission site density of the NCG films and current fluctuation measurements, it is concluded that several emission sites are generated inside the gate holes at the NCG–Si interface that exhibit gate voltage (Vg) -induced field enhancement. The field at these emission sites is expressed by E = βVg. © 2001 American Institute of Physics.
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79.70.+q Field emission, ionization, evaporation, and desorption
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Suppression of phase separation in (AlAs)2 ML(InAs)2 ML superlattices using Al0.48In0.52As monolayer insertions

S. R. Lee, J. L. Reno, and D. M. Follstaedt

Appl. Phys. Lett. 78, 3421 (2001); http://dx.doi.org/10.1063/1.1374521 (3 pages) | Cited 2 times

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Al0.48In0.52As monolayers (ML) are inserted at the binary-compound interfaces of (AlAs)2 ML(InAs)2 ML short-period superlattices (SPSs) during growth on (001) InP. The insertion of Al0.48In0.52As interlayers greater than 2 ML thick tends to suppress the phase separation that normally occurs during molecular beam epitaxy of the SPS. The degree of suppression is a sensitive function of both the monolayer-scale thickness, and the intraperiod growth sequence, of the interlayers in the SPS. Given this sensitivity to monolayer-scale variations in the surface-region composition, we propose that cyclical phase transition of the reconstructed surface initiates SPS decomposition. © 2001 American Institute of Physics.
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68.65.Cd Superlattices
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

How the nonrandom distribution of nuclei affects the island density in thin-film growth

M. Fanfoni, M. Tomellini, and M. Volpe

Appl. Phys. Lett. 78, 3424 (2001); http://dx.doi.org/10.1063/1.1375007 (3 pages) | Cited 7 times

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We propose a scheme of rate equations for stable dimers that permits the description quite satisfactorily of the evolution of the number of islands in the entire range of surface coverage. The characteristic time for coalescence and the capture number are computed through a stochastic approach for both random and nonrandom arrangements of nuclei. Rate equations are applied to describe kinetic Monte Carlo simulations previously published, in the whole range of surface coverages. It is found that to reproduce the simulation, the effect of the nonrandomicity of the nuclei distribution must be taken into account. © 2001 American Institute of Physics.
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81.15.Aa Theory and models of film growth
68.55.A- Nucleation and growth

Evolution of the electron energy distribution and plasma parameters in a pulsed magnetron discharge

J. T. Gudmundsson, J. Alami, and U. Helmersson

Appl. Phys. Lett. 78, 3427 (2001); http://dx.doi.org/10.1063/1.1376150 (3 pages) | Cited 63 times

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We demonstrate the creation of high-density plasma in a pulsed magnetron discharge. A 2.4 MW pulse, 100 μs wide, with a repetition frequency of 50 Hz is applied to a planar magnetron discharge to study the temporal behavior of the plasma parameters: the electron energy distribution function, the electron density, and the average electron energy. The electron density in the vicinity of the substrate, 20 cm below the cathode target, peaks at 8×1017 m−3, 127 μs after initiating the pulse. Towards the end of the pulse two energy groups of electrons are present with a corresponding peak in average electron energy. With the disapperance of the high-energy electron group, the electron density peaks, and the electron energy distribution appears to be Maxwellian like. Following the electron density peak, the plasma becomes more Druyvesteyn like with a higher average electron energy. © 2001 American Institute of Physics.
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81.15.Cd Deposition by sputtering
68.55.-a Thin film structure and morphology

Identification of ternary boron–carbon–nitrogen hexagonal phases by x-ray absorption spectroscopy

R. Gago, I. Jiménez, J. M. Albella, and L. J. Terminello

Appl. Phys. Lett. 78, 3430 (2001); http://dx.doi.org/10.1063/1.1376428 (3 pages) | Cited 26 times

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Boron carbon nitride (BCN) films have been grown by B4C evaporation with concurrent N2+ ion assistance, and have been characterized by x-ray absorption near edge (XANES) spectroscopy. Upon the nitrogen insertion, the film structure evolves from BxC-like to h-BN-like. The hexagonal structure corresponds to a true ternary BCN compound that can be understood as h-BN with carbon incorporated in substitutional sites. The C(1s)XANES presents π∗ states characteristic of the BCN arrangement. The basal planes of the h-BCN phase are oriented perpendicular to the substrate, as derived from the angle dependence of the XANES signal. © 2001 American Institute of Physics.
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68.55.Nq Composition and phase identification
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.
78.70.Dm X-ray absorption spectra

Electrochemical tuning of electronic states in single-wall carbon nanotubes studied by in situ absorption spectroscopy and ac resistance

S. Kazaoui, N. Minami, N. Matsuda, H. Kataura, and Y. Achiba

Appl. Phys. Lett. 78, 3433 (2001); http://dx.doi.org/10.1063/1.1372208 (3 pages) | Cited 49 times

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Electrochemical doping of single-wall carbon nanotube (SWNT) films and concomitant changes in their electronic states were investigated by in situ measurements of optical absorption spectra as well as of ac resistance using a nonaqueous electrolyte solution. A systematic, consistent, and reversible variation of these properties induced by the shift in the electrode potential demonstrated the practicability of fine and continuous tuning of their electronic states. Analysis of the potential dependence of the absorbance at 0.68 eV enabled the estimation of average values of the electron affinity (4.8 eV) and the first ionization potential (5.4 eV) of semiconducting SWNTs. © 2001 American Institute of Physics.
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73.22.Dj Single particle states
73.63.Fg Nanotubes
78.67.Ch Nanotubes
78.30.Na Fullerenes and related materials
81.07.De Nanotubes
82.45.Mp Thin layers, films, monolayers, membranes
61.72.up Other materials
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Photoluminescence properties of the Eu3+ activator ion in the TiO2 host matrix

A. Conde-Gallardo, M. García-Rocha, I. Hernández-Calderón, and R. Palomino-Merino

Appl. Phys. Lett. 78, 3436 (2001); http://dx.doi.org/10.1063/1.1372338 (3 pages) | Cited 46 times

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Titania (TiO2) is employed as a host for the Eu3+ activator ion. Thin films were produced by the sol-gel method on silicon and corning glass substrates and, depending on the nature of the substrate, they present different crystalline structure. The films show an intense red photoluminescence associated with the 5D0→7F2 transition of the electronic structure of Eu3+. The photoluminescence presents better characteristics for the films deposited on silicon wafers. For above band gap excitation the emission from the TiO2 matrix is obscured by the luminescence of the Eu3+ ions. The peak energy position, the spectral shape, and the width are insensitive to changes of temperature in the 12–300 K range, making the TiO2:Eu3+ a very attractive system for technological applications. © 2001 American Institute of Physics.
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78.55.Hx Other solid inorganic materials
78.66.Li Other semiconductors
71.55.Ht Other nonmetals

Nanoanalysis of Co/Cu/NiFe thin films by tomographic atom probe

J. Schleiwies, G. Schmitz, S. Heitmann, and A. Hütten

Appl. Phys. Lett. 78, 3439 (2001); http://dx.doi.org/10.1063/1.1374999 (3 pages) | Cited 13 times

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Offering the possibility of improving data storage and magnetic sensoric, applications of giant magnetoresistance (GMR) in thin metallic films are of great interest. In order to study thermal reactions in such layered structures, atom probe tomography is used, which has been proven to perform a real three-dimensional analysis on the relevant length scale of several angstroms only. Co/Cu/Ni79Fe21 layered structures were deposited on tungsten substrate tips by ion beam sputtering and analyzed in the as-prepared state and after suitable heat treatments. After annealing at 250 °C for 30 min, Fe segregation at the Co/Cu interface inside the Co layer is clearly observed. This effect may be interpreted as an interface dusting potentially increasing the GMR. After annealing at 350 °C for 30 min, an additional Ni segregation inside Cu grain boundaries is observed. It is suggested that this segregation path forms the initial stage of pinhole formation and finally causes ferromagnetic bridges through the paramagnetic coupling layer. © 2001 American Institute of Physics.
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68.65.Ac Multilayers
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.47.De Giant magnetoresistance
68.35.Fx Diffusion; interface formation
68.35.Dv Composition, segregation; defects and impurities
68.37.Vj Field emission and field-ion microscopy

Separation of vacancy and interstitial depth profiles in ion-implanted silicon: Experimental observation

P. Pellegrino, P. Lévêque, J. Wong-Leung, C. Jagadish, and B. G. Svensson

Appl. Phys. Lett. 78, 3442 (2001); http://dx.doi.org/10.1063/1.1374960 (3 pages) | Cited 17 times

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An experimental concept of studying shifts between concentration-versus-depth profiles of vacancy and interstitial-type defects in ion-implanted silicon is demonstrated. This concept is based on deep level transient spectroscopy measurements where the filling pulse width is varied. The vacancy profile, represented by the vacancy-oxygen center, and the interstitial profile, represented by the substitutional carbon–interstitial carbon pair, are obtained at the same sample temperature and can be recorded with a high relative depth resolution. For 6 MeV 11B ions, the peak of the interstitial profile is displaced by ∼0.5 μm towards larger depths compared to that of the vacancy profile, which is primarily attributed to the preferential forward momentum of recoiling Si atoms. © 2001 American Institute of Physics.
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71.55.Cn Elemental semiconductors
61.72.uf Ge and Si
61.82.Fk Semiconductors
61.72.S- Impurities in crystals
61.80.Jh Ion radiation effects
61.72.J- Point defects and defect clusters

Electrical transients in the ion-beam-induced nitridation of silicon

Mladen Petravic and Prakash N. K. Deenapanray

Appl. Phys. Lett. 78, 3445 (2001); http://dx.doi.org/10.1063/1.1376661 (3 pages) | Cited 4 times

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We have studied the dynamics of the initial stages of silicon nitride formation on silicon surfaces under nitrogen beam bombardment in the secondary ion mass spectrometry apparatus. We have shown that the secondary ion signal exhibits damped oscillations below the critical impact angle for nitride formation. We have described this oscillatory response by a second-order differential equation and argued that it is initiated by some fluctuations in film thickness followed by the fluctuations in surface charging. © 2001 American Institute of Physics.
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81.65.Lp Surface hardening: nitridation, carburization, carbonitridation
61.82.Fk Semiconductors
81.05.Cy Elemental semiconductors
61.80.Jh Ion radiation effects
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Effects of interface roughness and phonon scattering on intersubband absorption linewidth in a GaAs quantum well

Takeya Unuma, Teruyuki Takahashi, Takeshi Noda, Masahiro Yoshita, Hiroyuki Sakaki, Motoyoshi Baba, and Hidefumi Akiyama

Appl. Phys. Lett. 78, 3448 (2001); http://dx.doi.org/10.1063/1.1376154 (3 pages) | Cited 24 times

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We experimentally and theoretically study the effects of interface roughness and phonon scattering on intersubband absorption linewidth in a modulation-doped GaAs/AlAs quantum well. Quantitative comparisons between experimental results and theoretical calculations make it clear that interface roughness scattering is the dominant scattering mechanism for absorption linewidth in the temperature range below 300 K. Even at room temperature, phonon scattering processes contribute little to linewidth, while polar-optical phonon scattering limits electron mobility. © 2001 American Institute of Physics.
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78.67.De Quantum wells
68.65.Fg Quantum wells
73.21.Fg Quantum wells
73.63.Hs Quantum wells
78.30.Fs III-V and II-VI semiconductors
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials

Electromigration in Cu interconnects with very different grain structures

C. S. Hau-Riege and C. V. Thompson

Appl. Phys. Lett. 78, 3451 (2001); http://dx.doi.org/10.1063/1.1355304 (3 pages) | Cited 46 times

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To determine the effects of grain structures on the rate of electromigration-induced failure of Cu interconnects, scanned laser annealing (SLA) has been used to produce Cu interconnects with very different grain structures. SLA, in which a moving hot-zone induces local grain growth, can be used to produce interconnects with fully bamboo grain structures that have bamboo grain lengths up to ten times the interconnect width. Electromigration experiments have been carried out on interconnects with very-long-grained bamboo structures, as well as on interconnects with polygranular structures in which the average grain size is less than the linewidth. Such differences are known to lead to orders of magnitude changes in lifetimes for Al-based interconnects. However, no significant differences in the failure rates were found for these Cu interconnects. This result supports earlier work that suggested that electromigration in Cu interconnects with now-standard liners and interlevel diffusion-barrier layers occurs by mechanisms that are faster than grain boundary self-diffusion. © 2001 American Institute of Physics.
Show PACS
85.40.Ls Metallization, contacts, interconnects; device isolation
85.40.Qx Microcircuit quality, noise, performance, and failure analysis
66.30.Qa Electromigration
61.72.Mm Grain and twin boundaries
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.Cc Kinetics of defect formation and annealing
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