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25 Jan 1999

Volume 74, Issue 4, pp. 483-629

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Radiative and nonradiative recombination processes in ultraviolet light-emitting diode composed of an In0.02Ga0.98N active layer

Yukio Narukawa, Shin Saijou, Yoichi Kawakami, Shigeo Fujita, Takashi Mukai, and Shuji Nakamura

Appl. Phys. Lett. 74, 558 (1999); http://dx.doi.org/10.1063/1.123144 (3 pages) | Cited 46 times

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Radiative and nonradiative recombination processes have been studied in ultraviolet In0.02Ga0.98N light-emitting diodes (LEDs), by employing photoinduced voltage, electroreflectance, and time-resolved photoluminescence spectroscopy. It was found that excitons in the In0.02Ga0.98N active layer are weakly localized at low temperature, and delocalized above about 70 K, showing a three-dimensional feature in the temperature dependence of the radiative lifetime. The external quantum efficiency (ηext) of this LED is about ten times higher than the LED whose active layer is composed of GaN. Improvement of the ηext value by the addition of a small amount of In to the active layer is attributed to the suppression of the density of the nonradiative recombination center (NRC), as well as possibly to where the origin of the NRC is changed. © 1999 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
78.20.Jq Electro-optical effects
78.47.-p Spectroscopy of solid state dynamics
71.35.Cc Intrinsic properties of excitons; optical absorption spectra
73.20.Fz Weak or Anderson localization

Schottky energy barriers and charge injection in metal/Alq/metal structures

I. H. Campbell and D. L. Smith

Appl. Phys. Lett. 74, 561 (1999); http://dx.doi.org/10.1063/1.123145 (3 pages) | Cited 49 times

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We present internal photoemission, photocurrent versus bias voltage, and current–voltage measurements of metal/tris-(8-hydroxyquinoline) aluminum [Alq]/metal structures. Internal photoemission and photocurrent versus bias measurements were used to determine metal/Alq Schottky energy barriers for a range of contact metals with work functions from 2.7 eV (Sm) to 5.6 eV (Pt). The electron Schottky barrier for low work-function metals (<about 3.6 eV) is pinned at about 0.6 eV. For metals with higher work functions (> about 3.6 eV) the ideal Schottky model is generally accurate. A previously established device model was used to describe the current–voltage characteristics using the measured Schottky barriers. The results imply comparable electron and hole mobilities of about 2×10−5 cm2/V s at an electric field of 106 V/cm. © 1999 American Institute of Physics.
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73.40.Sx Metal-semiconductor-metal structures
73.50.Pz Photoconduction and photovoltaic effects
73.30.+y Surface double layers, Schottky barriers, and work functions

Controlled tuning of the radiative lifetime in InAs self-assembled quantum dots through vertical ordering

M. Colocci, A. Vinattieri, L. Lippi, F. Bogani, M. Rosa-Clot, S. Taddei, A. Bosacchi, S. Franchi, and P. Frigeri

Appl. Phys. Lett. 74, 564 (1999); http://dx.doi.org/10.1063/1.123146 (3 pages) | Cited 44 times

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Multilayer structures of InAs quantum dots have been studied by means of photoluminescence techniques. A strong increase of the radiative lifetime with increasing number of stacked dot layers has been observed at low temperatures. Moreover, a strong temperature dependence of the radiative lifetime, which is not present in the single layer samples, has been found in the multistacked structures. The observed effects are nicely explained as a consequence of the electronic coupling between electrons and holes induced by vertical ordering. © 1999 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Spontaneous self-embedding of three-dimensional SiGe islands

E. Mateeva, P. Sutter, and M. G. Lagally

Appl. Phys. Lett. 74, 567 (1999); http://dx.doi.org/10.1063/1.123147 (3 pages) | Cited 16 times

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It is shown that, under appropriate conditions, high-Ge-concentration coherent three-dimensional SiGe islands grown on Si(100) self-embed in a matrix of a low-Ge-concentration alloy. The process may be more generally useful for preserving the shape of self-assembled “quantum dot” islands during embedding in a matrix material. © 1999 American Institute of Physics.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.05.Hd Other semiconductors
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Lateral epitaxial overgrowth of GaN films on sapphire and silicon substrates

P. Kung, D. Walker, M. Hamilton, J. Diaz, and M. Razeghi

Appl. Phys. Lett. 74, 570 (1999); http://dx.doi.org/10.1063/1.123148 (3 pages) | Cited 25 times

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We report the lateral epitaxial overgrowth of GaN films on (00.1) Al2O3 and (111) Si substrates by metalorganic chemical vapor deposition. The lateral epitaxial overgrowth on Si substrates was possible after achieving quasimonocrystalline GaN template films on (111) Si substrates. X-ray diffraction, photoluminescence, scanning electron microscopy, and atomic force microscopy were used to assess the quality of the lateral epitaxial overgrown films. Lateral growth rates more than five times as high as vertical growth rates were achieved for both lateral epitaxial overgrowths of GaN on sapphire and silicon substrates. © 1999 American Institute of Physics.
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81.05.Ea III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.35.B- Structure of clean surfaces (and surface reconstruction)
78.66.Fd III-V semiconductors

Piezoelectric polarization associated with dislocations in wurtzite GaN

Changchun Shi, Peter M. Asbeck, and Edward T. Yu

Appl. Phys. Lett. 74, 573 (1999); http://dx.doi.org/10.1063/1.123149 (3 pages) | Cited 29 times

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The piezoelectric polarization and its associated charge density are calculated for edge, screw, and mixed dislocations oriented parallel to the c axis in wurtzite GaN. It is shown that the polarization field generated by screw components of dislocations is divergence free, and thus does not generate electric fields. Edge dislocations produce polarization fields that have nonzero divergence only at interfaces. These characteristics minimize the electrical and optical effects of the dislocations mediated by the piezoelectric effect. © 1999 American Institute of Physics.
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77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.22.Ej Polarization and depolarization
77.65.-j Piezoelectricity and electromechanical effects
61.72.Lk Linear defects: dislocations, disclinations

Electrically active defect centers induced by Ga+ focused ion beam irradiation of GaAs(100)

S. J. Brown, P. D. Rose, G. A. C. Jones, E. H. Linfield, and D. A. Ritchie

Appl. Phys. Lett. 74, 576 (1999); http://dx.doi.org/10.1063/1.123150 (3 pages) | Cited 6 times

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The electronic nature of defect centers induced by 30 keV Ga+ focused ion beam irradiation of GaAs(100) has been studied in situ by scanning tunneling spectroscopy (STS). The defect centers were identified as electron traps lying below the surface state conduction band, each with an active area of approximately 20 nm2. An areal ion beam dose of 1×1013 cm−2 was sufficiently low that no significant surface sputtering was observed by topographic imaging which suggests that the features observed by STS are not related to gross physical damage. Spatial STS measurements also allow a lateral profile of a focused ion beam patterned line to be determined accurately, thereby setting a resolution limit on the direct write technique for nanoscale lithography. © 1999 American Institute of Physics.
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71.55.Eq III-V semiconductors
73.20.Hb Impurity and defect levels; energy states of adsorbed species
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy
85.40.Hp Lithography, masks and pattern transfer
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices

Issues on the molecular-beam epitaxial growth of p-SiGe inverted-modulation-doped structures

M. A. Sadeghzadeh, C. P. Parry, P. J. Phillips, E. H. C. Parker, and T. E. Whall

Appl. Phys. Lett. 74, 579 (1999); http://dx.doi.org/10.1063/1.123151 (3 pages) | Cited 4 times

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The influence of boron segregation and silicon cap-layer thickness on two-dimensional hole gases (2-DHGs) has been investigated in Si/Si0.8Ge0.2/Si inverted-modulation-doped heterostructures grown by solid-source molecular-beam epitaxy. Boron segregation, which is significant in structures with small spacer layers, can be suppressed by growth interruption after the boron doping. How growth interruption affected the electrical properties of the 2-DHG and the boron doping profile as measured by secondary ion mass spectroscopy are reported. We report also on the role played by the unpassivated silicon cap, and compare carrier transport at the normal and inverted interfaces. © 1999 American Institute of Physics.
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81.05.Hd Other semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
73.61.Le Other inorganic semiconductors
61.72.up Other materials
61.72.S- Impurities in crystals
64.75.-g Phase equilibria
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Issues in general quantum transport with complex potentials

D. K. Ferry and J. R. Barker

Appl. Phys. Lett. 74, 582 (1999); http://dx.doi.org/10.1063/1.123152 (3 pages) | Cited 7 times

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Complex potentials have been used previously to simulate dissipative processes in quantum simulations of transport and scattering. A general formulation is presented which shows how such non-Hermitian terms can lead to changes in the dynamics of transport operators, and to the decay of hydrodynamic quantities such as phase, energy, and momentum. © 1999 American Institute of Physics.
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72.10.Bg General formulation of transport theory

An embedded quantum wire model of dielectric breakdown

D. Z.-Y. Ting

Appl. Phys. Lett. 74, 585 (1999); http://dx.doi.org/10.1063/1.123153 (3 pages) | Cited 9 times

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The reverse gate bias current–voltage characteristics of n+ polycrystalline-Si/SiO2/p-Si tunnel structures containing nanoscale quantum wires embedded in ultrathin oxide layers are analyzed using a three-dimensional quantum mechanical scattering calculation. By varying wire geometry, our model can qualitatively reproduce experimental current–voltage characteristics for ultrathin oxides having undergone soft breakdown or breakdown. We find that low-bias current densities can be greatly enhanced by resonant tunneling, and that this mechanism is highly temperature dependent. We demonstrate that funneling of wave functions into quantum wires results in highly efficient localized conduction paths which contributes to dramatic current increases in the direct tunneling regime. We also explain how quantum wires which extend partially into the oxide layer from the SiO2/p-Si interface can be used to model soft breakdown current–voltage characteristics. © 1999 American Institute of Physics.
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73.40.Ty Semiconductor-insulator-semiconductor structures
73.40.Gk Tunneling
77.22.Jp Dielectric breakdown and space-charge effects
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Fabrication of nanomagnet arrays by shadow deposition on self-organized semiconductor substrates

C. Teichert, J. Barthel, H. P. Oepen, and J. Kirschner

Appl. Phys. Lett. 74, 588 (1999); http://dx.doi.org/10.1063/1.123154 (3 pages) | Cited 19 times

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It is demonstrated how large-scale arrays of nanomagnets can be efficiently fabricated by shadow deposition onto faceted surfaces of self-organized Si1−xGex films. By pulsed laser deposition of Co in a grazing incidence geometry, we succeeded to cover just one selected type of facets resulting in isolated Co patches with an areal density of about 0.25×1012/in.2. These uniformly oriented nanomagnets have a parallelogram-shaped base with about 25 nm×35 nm edge lengths. Magneto-optic Kerr effect measurements reveal a clear in-plane anisotropy of the nanomagnets. © 1999 American Institute of Physics.
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75.50.Kj Amorphous and quasicrystalline magnetic materials
81.07.-b Nanoscale materials and structures: fabrication and characterization
75.70.Ak Magnetic properties of monolayers and thin films
81.15.Fg Pulsed laser ablation deposition
75.50.Cc Other ferromagnetic metals and alloys
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Gw Magnetic anisotropy
78.20.Ls Magneto-optical effects

Isomagnetic reversal in sintered NdFeB

D. C. Crew, P. G. McCormick, and R. Street

Appl. Phys. Lett. 74, 591 (1999); http://dx.doi.org/10.1063/1.123155 (3 pages) | Cited 7 times

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Measurements of reversible and irreversible magnetization have been used to examine the reversal process on the initial magnetization curve in sintered NdFeB. It is found that the reversal process involves equal and opposite changes of irreversible and reversible magnetization, described here as isomagnetic reversal, resulting in no net change in magnetization during reversal. This result is consistent with the observation that magnetic viscosity is negligible on the initial magnetization curve. © 1999 American Institute of Physics.
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75.50.Ww Permanent magnets
75.50.Bb Fe and its alloys
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Improvement in spin-wave resonance characteristics of epitaxial barium-ferrite thin films by using an aluminum-doped strontium-ferrite buffer layer

S. R. Shinde, S. E. Lofland, C. S. Ganpule, S. M. Bhagat, S. B. Ogale, R. Ramesh, and T. Venkatesan

Appl. Phys. Lett. 74, 594 (1999); http://dx.doi.org/10.1063/1.123156 (3 pages) | Cited 10 times

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We report on the effects of using SrFe7Al5O19 as a buffer layer for growth of high-quality epitaxial barium-ferrite thin films on sapphire substrates. X-ray diffraction studies reveal that the buffer layer causes the interfacial strains in the barium-ferrite films to relax. As a result, the ferromagnetic resonance linewidth decreases even in the as-deposited case. However, the more striking result is the drastic reduction in the linewidth that occurs when the barium-ferrite film is deposited on the buffer layer and subsequently annealed at 1000 °C for 2 h, allowing the observation of a large number of spin-wave resonances (up to the 15th mode), indicating an improvement in both the surface and interface characteristics. © 1999 American Institute of Physics.
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76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
75.50.Gg Ferrimagnetics
75.70.Ak Magnetic properties of monolayers and thin films
68.60.Bs Mechanical and acoustical properties

Microstructure and magnetic properties of Sm2(Fe, Si)17Cx/α-Fe nanocomposite magnets prepared under high pressure

X. Y. Zhang, J. W. Zhang, W. K. Wang, W. Yu, J. H. Zhao, and Y. F. Xu

Appl. Phys. Lett. 74, 597 (1999); http://dx.doi.org/10.1063/1.123157 (3 pages) | Cited 19 times

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We present microstructure and magnetic properties of Sm2(Fe, Si)17Cx/α-Fe nanocomposite magnets prepared under a pressure of 4 GPa at a temperature of 923 K. A high-pressure experiment was carried out in a belt-type pressure apparatus. Analyses of x-ray diffraction and transmission electron microscopy show that the nanocomposite magnets have a grain size of 6–8 nm, which provides a strong exchange coupling between hard and soft magnetic phases. As a result, the magnets have, compared with nanocomposite magnets prepared under normal pressure, a significant increase in both coercivity, from 132 to 500 kA/m, and remanent magnetization, from 0.68 to 0.83Ms. © 1999 American Institute of Physics.
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75.50.Ww Permanent magnets
75.50.Vv High coercivity materials
61.72.-y Defects and impurities in crystals; microstructure
61.46.-w Structure of nanoscale materials
75.50.Kj Amorphous and quasicrystalline magnetic materials
81.07.-b Nanoscale materials and structures: fabrication and characterization
62.50.-p High-pressure effects in solids and liquids
75.30.Et Exchange and superexchange interactions
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Bb Fe and its alloys

Electrical noise in hysteretic ferromagnet–insulator–ferromagnet tunnel junctions

E. R. Nowak, M. B. Weissman, and S. S. P. Parkin

Appl. Phys. Lett. 74, 600 (1999); http://dx.doi.org/10.1063/1.123158 (3 pages) | Cited 8 times

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Low frequency noise has been measured in magnetic tunnel junctions that have Al2O3 tunnel barriers and magnetoresistance values up to 35% at 295 K. Fluctuations in voltage were found to cross over from Johnson noise to shot noise at low bias voltages, in quantitative agreement with theories of noise in quantum ballistic systems. 1/f resistance noise, where f is frequency, predominates at larger biases and is proportional to the mean current squared. This noise is attributed to trapping processes and it depends sensitively on the relative position of the oxide edge and the ferromagnet–Al interface. © 1999 American Institute of Physics.
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73.40.Rw Metal-insulator-metal structures
73.50.Td Noise processes and phenomena
73.40.Gk Tunneling
75.45.+j Macroscopic quantum phenomena in magnetic systems
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
75.70.-i Magnetic properties of thin films, surfaces, and interfaces
75.50.Bb Fe and its alloys
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BaBi4Ti4O15 ferroelectric thin films grown by pulsed laser deposition

K. M. Satyalakshmi, M. Alexe, A. Pignolet, N. D. Zakharov, C. Harnagea, S. Senz, and D. Hesse

Appl. Phys. Lett. 74, 603 (1999); http://dx.doi.org/10.1063/1.123159 (3 pages) | Cited 35 times

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BaBi4Ti4O15 (BBiT) is an n = 4 member of the Bi-layer-structured ferroelectric oxide family (Aurivillius phases). BBiT thin films with preferred orientations have been grown on epitaxial conducting LaNiO3 electrodes on (001) SrTiO3 by pulsed laser deposition. Cross-section electron microscopy analysis reveals that the films consist of ct-axis oriented regions and mixed at- and ct-axis oriented regions. The mixed at- and ct-axis oriented regions show high surface roughness due to the rectangular crystallites protruding out of the surface, whereas the ct-axis oriented regions show a smooth surface morphology. In the mixed at- and ct-axis oriented regions, the BBiT films exhibit saturated ferroelectric hysteresis loops with remnant polarization Pr of 2 μC/cm2 and coercive field Ec of 60 kV/cm and no polarization fatigue up to 108 cycles. The regions having ct-axis orientation with a smooth surface morphology exhibit a linear P–E curve. The results show that the ferroelectric properties of a planar capacitor consisting of BBiT depend on the crystalline orientation of the film. © 1999 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
81.15.Fg Pulsed laser ablation deposition
77.80.Dj Domain structure; hysteresis
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.55.-a Thin film structure and morphology
77.22.Ej Polarization and depolarization

Low dielectric constant Parylene-F-like films for intermetal dielectric applications

Bengi Hanyaloglu, Atilla Aydinli, Michael Oye, and Eray S. Aydi

Appl. Phys. Lett. 74, 606 (1999); http://dx.doi.org/10.1063/1.123160 (3 pages) | Cited 7 times

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We report on the dielectric properties and thermal stability of thin polymer films that are suitable candidates for replacing silicon dioxide as the intermetal dielectric material in integrated circuits. Parylene-F-like films, (–CF2–C6H4–CF2–)n, were produced by plasma deposition from a mixture of Ar and 1,4-bis(trifluoromethyl)benzene (CF3–C6H4–CF3) discharges and characterized using infrared absorption spectroscopy, spectroscopic ellipsometry, and capacitance measurements. The dielectric constant and the magnitude of the electronic and ionic contributions to the dielectric constant were determined through capacitance measurements and Kramers–Kronig analysis of the infrared absorption data. The film’s dielectric constant ranges between 2 and 2.6 depending on the deposition conditions and the largest contribution to the dielectric constant is electronic. The films deposited at 300 °C are stable above 400 °C and further optimization could push this limit to as high as 500 °C. © 1999 American Institute of Physics.
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77.55.-g Dielectric thin films
68.60.Dv Thermal stability; thermal effects
85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology
78.35.+c Brillouin and Rayleigh scattering; other light scattering
78.66.Qn Polymers; organic compounds
77.22.Ch Permittivity (dielectric function)
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Enhanced hole injection in a bilayer vacuum-deposited organic light-emitting device using a p-type doped silicon anode

X. Zhou, J. He, L. S. Liao, M. Lu, Z. H. Xiong, X. M. Ding, X. Y. Hou, F. G. Tao, C. E. Zhou, and S. T. Lee

Appl. Phys. Lett. 74, 609 (1999); http://dx.doi.org/10.1063/1.123161 (3 pages) | Cited 45 times

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We report the fabrication of a vacuum-deposited light-emitting device which emits light from its top surface through an Al cathode using p-type doped silicon as the anode material. Enhanced hole injection is clearly demonstrated from the p-Si anode as compared to the indium–tin–oxide (ITO) anode. The mechanisms of hole injection from both the p-Si and ITO anodes into the organic layer are investigated and a possible model based on anode surface band bending is proposed. During the operation of the organic light-emitting device, the surface band bending of the anode plays a very important role in modifying the interfacial barrier height between the anode and the organic layer. © 1999 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.66.Qn Polymers; organic compounds
78.60.Fi Electroluminescence
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
73.20.-r Electron states at surfaces and interfaces

65 GHz InGaAs/InAlGaAs/InP waveguide-integrated photodetectors for the 1.3–1.55 μm wavelength regime

St. Kollakowski, A. Strittmatter, E. Dröge, E. H. Böttcher, D. Bimberg, O. Reimann, and K. Janiak

Appl. Phys. Lett. 74, 612 (1999); http://dx.doi.org/10.1063/1.123181 (3 pages) | Cited 8 times

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We report on ultrafast waveguide-integrated metal-semiconductor-metal photodetectors based on low pressure metal organic chemical vapor deposition grown semiinsulating InP/InGaAs/InAlGaAs/InP layers. The vertically coupled detectors have an internal coupling efficiency of >90% at 1.3 and 1.55 μm wavelength for detector lengths of 30 μm. A 3 dB bandwidth of 65 GHz at 1.55 μm wavelength is achieved by employing 0.3 μm feature-size finger electrodes and an active layer thickness of 150 nm. Furthermore, we present results on high-performance devices with a buried waveguide structure fabricated by regrowth of InP:Fe. © 1999 American Institute of Physics.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
42.82.Et Waveguides, couplers, and arrays
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
81.05.Ea III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

A thin-film diamond phototransistor

Stuart P. Lansley, Hui Jin Looi, Yanyang Wang, Michael D. Whitfield, and Richard B. Jackman

Appl. Phys. Lett. 74, 615 (1999); http://dx.doi.org/10.1063/1.123182 (3 pages) | Cited 9 times

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A phototransistor fabricated from thin-film diamond is reported. Polycrystalline diamond grown by chemical vapor deposition, which is p-type by virtue of near-surface hydrogen, has been used to realize optically activated metal–semiconductor field-effect transistors (FETs). Devices with thin (30 nm) Al Schottky gates and Au source and drain contacts operate as effective enhancement-mode metal–semiconductor field-effect transistors at room temperature; illumination of an electrically isolated gate leads to increased channel current, although saturation is still evident. At deep UV wavelengths (<220 nm), a photodetector gain of around 4 has been measured; the mechanism of operation has been identified as photodiode-like turn-on followed by FET amplification. © 1999 American Institute of Physics.
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85.60.Dw Photodiodes; phototransistors; photoresistors
85.60.Gz Photodetectors (including infrared and CCD detectors)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.05.ub Fullerenes and related materials
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Microscopic observation of weak electric fields

W. Laï, A. Degiovanni, and R. Morin

Appl. Phys. Lett. 74, 618 (1999); http://dx.doi.org/10.1063/1.123183 (3 pages) | Cited 11 times

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Weak electric fields in vacuum around conductors like small metallic wires or tips are observed using a low-energy electron point projection microscope operating in interferential mode. Observations are made at room temperature with a sensitivity of a few hundred millivolts per micrometer and submicrometer spatial resolution. © 1999 American Institute of Physics.
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84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
07.78.+s Electron, positron, and ion microscopes; electron diffractometers

Grain boundary barrier breakdown in niobium donor doped strontium titanate using in situ electron holography

Kevin D. Johnson and Vinayak P. Dravid

Appl. Phys. Lett. 74, 621 (1999); http://dx.doi.org/10.1063/1.123184 (3 pages) | Cited 22 times

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The electrical activity of numerous electroceramics originates with space charge potential across internal interfaces. Space charge formation and the resultant potential barrier at interfaces are believed to be responsible for many interesting and useful properties of electroceramics, ranging from nonlinear current–voltage characteristics to enhanced dielectric properties. Direct current electrical measurements of individual grain boundaries in Nb donor doped SrTiO3 bicrystals reveal a highly resistive and nonlinear behavior compared to single crystals. The origin of this nonlinear resistance has been examined with electron holography, observing both static and dynamic attributes of the internal potential. In the static case with no applied current, the grain boundary potential barrier height was measured to be about 0.45 V. During the application of a high current, this potential barrier was suppressed, presenting the first direct real space evidence for breakdown of an internal grain boundary barrier. © 1999 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
61.72.Mm Grain and twin boundaries
77.22.Jp Dielectric breakdown and space-charge effects
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
72.20.Ht High-field and nonlinear effects
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Comment on “The larger polar Kerr rotation of Fe–Si alloy films and their magnetic properties” [Appl. Phys. Lett. 72, 1383 (1998)]

R. Krishnan

Appl. Phys. Lett. 74, 624 (1999); http://dx.doi.org/10.1063/1.123187 (1 page)

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78.20.Ls Magneto-optical effects
75.50.Bb Fe and its alloys
75.70.Ak Magnetic properties of monolayers and thin films
75.50.Kj Amorphous and quasicrystalline magnetic materials
78.66.Bz Metals and metallic alloys
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Addendum: “Midinfrared vertical-cavity surface-emitting laser” [Appl. Phys. Lett. 71, 3483 (1997)]

W. W. Bewley, C. L. Felix, I. Vurgaftman, L. J. Olafsen, E. H. Aifer, and J. R. Meyer

Appl. Phys. Lett. 74, 625 (1999); http://dx.doi.org/10.1063/1.123185 (3 pages) | Cited 2 times

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A number of issues related to pulsed-power determinations for midinfrared semiconductor lasers are reexamined. Especially useful is a Green’s function approach to incorporating the temporal dependence of the detector sensitivity. A method for extracting the external differential efficiency when the threshold is “soft” is also presented. © 1999 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Rn Relaxation oscillations and long pulse operation
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Errata: “Midinfrared vertical-cavity surface-emitting laser” [Appl. Phys. Lett. 71, 3483 (1997)] “High-temperature type-II superlattice diode laser at λ=2.9 μm” [Appl. Phys. Lett. 71, 3607 (1997)] “Near-room-temperature midinfrared interband cascade laser” [Appl. Phys. Lett. 72, 2370 (1998)]

C. L. Felix, W. W. Bewley, I. Vurgaftman, J. R. Meyer, L. Goldberg, E. H. Aifer, L. J. Olafsen, D. H. Chow, E. Selvig, C.-H. Lin, S. J. Murry, D. Zhang, and S. S. Pei

Appl. Phys. Lett. 74, 628 (1999); http://dx.doi.org/10.1063/1.123188 (2 pages) | Cited 1 time

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Abstract Unavailable
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
78.66.Fd III-V semiconductors
99.10.Cd Errata
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