APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

13 May 2002

Volume 80, Issue 19, pp. 3467-3650

Page 2 of 3 Pages Previous Page Next Page | Jump to Page
back to top
RSS Feeds

Crack-free thick AlGaN grown on sapphire using AlN/AlGaN superlattices for strain management

J. P. Zhang, H. M. Wang, M. E. Gaevski, C. Q. Chen, Q. Fareed, J. W. Yang, G. Simin, and M. Asif Khan

Appl. Phys. Lett. 80, 3542 (2002); http://dx.doi.org/10.1063/1.1477620 (3 pages) | Cited 57 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on an AlN/AlGaN superlattice approach to grow high-Al-content thick n+-AlGaN layers over c-plane sapphire substrates. Insertion of a set of AlN/AlGaN superlattices is shown to significantly reduce the biaxial tensile strain, thereby resulting in 3-μm-thick, crack-free Al0.2Ga0.8N layers. These high-quality, low-sheet-resistive layers are of key importance to avoid current crowding in quaternary AlInGaN multiple-quantum-well deep-ultraviolet light-emitting diodes over sapphire substrates. © 2002 American Institute of Physics.
Show PACS
81.07.St Quantum wells
81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.60.Bs Mechanical and acoustical properties
73.61.Ey III-V semiconductors
68.55.-a Thin film structure and morphology
85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
72.20.Ee Mobility edges; hopping transport
72.20.My Galvanomagnetic and other magnetotransport effects
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

In-doped SrTiO3 ceramic thin films

Shouyu Dai, Huibin Lu, Fan Chen, Zhenghao Chen, Z. Y. Ren, and D. H. L. Ng

Appl. Phys. Lett. 80, 3545 (2002); http://dx.doi.org/10.1063/1.1478148 (3 pages) | Cited 15 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the characterization of the ceramic SrIn0.1Ti0.9O3 thin film grown by laser molecular-beam epitaxy. The lattice constant is determined to be 0.3948 nm, slightly larger than that of the SrTiO3 substrate. Hall measurement confirms that this film is a p-type semiconductor either below 92 K or above 158 K. X-ray photoemission spectroscopy study shows that the width of the valence band of the p-type SrIn0.1Ti0.9O3 film is narrower than that of the n-type SrNb0.1Ti0.9O3 film. There is a 0.35 eV difference in the Fermi energy level of the two films. The electronic state of the surface layer of the SrIn0.1Ti0.9O3 film is found to be different from that of its interior. © 2002 American Institute of Physics.
Show PACS
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
81.15.Fg Pulsed laser ablation deposition
73.61.Le Other inorganic semiconductors
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
79.60.Bm Clean metal, semiconductor, and insulator surfaces
68.55.-a Thin film structure and morphology

Electrical transport properties of individual gallium nitride nanowires synthesized by chemical-vapor-deposition

Jae-Ryoung Kim, Hye Mi So, Jong Wan Park, Ju-Jin Kim, Jinhee Kim, Cheol Jin Lee, and Seung Chul Lyu

Appl. Phys. Lett. 80, 3548 (2002); http://dx.doi.org/10.1063/1.1478158 (3 pages) | Cited 71 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have synthesized high-quality gallium nitride (GaN) nanowires by a chemical-vapor-deposition method and studied the electrical transport properties. The electrical measurements on individual GaN nanowires show a pronounced n-type field effect due to nitrogen vacancies in the whole measured temperature ranges. The n-type gate response and the temperature dependence of the current–voltage characteristics could be understood by the band bending at the interface of the metal electrode and GaN wire. The estimated electron mobility from the gate modulation characteristics is about 2.15 cm2/V s at room temperature, suggesting the diffusive nature of electron transport in the nanowires. © 2002 American Institute of Physics.
Show PACS
73.63.Bd Nanocrystalline materials
81.05.Ea III-V semiconductors
81.07.Bc Nanocrystalline materials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
61.72.J- Point defects and defect clusters
61.46.-w Structure of nanoscale materials

Direct measurement of the polarization charge in AlGaN/GaN heterostructures using capacitance–voltage carrier profiling

E. J. Miller, E. T. Yu, C. Poblenz, C. Elsass, and J. S. Speck

Appl. Phys. Lett. 80, 3551 (2002); http://dx.doi.org/10.1063/1.1477275 (3 pages) | Cited 22 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The polarization charge at AlxGa1−xN/GaN heterostructure interfaces arising from differences in spontaneous polarization between AlxGa1−xN and GaN and the presence of piezoelectric polarization in strained layers has been directly measured using capacitance–voltage carrier profiling in GaN/AlxGa1−xN/GaN heterostructures with varying Al composition grown by molecular-beam epitaxy. The measured polarization charge densities (2.36±0.30×1012 e/cm2, 6.79±0.48×1012 e/cm2, and 6.92±0.74×1012 e/cm2 for 5%, 12%, and 16% AlxGa1−xN/GaN interfaces, respectively) reveal substantial bowing in the polarization charge as a function of Al composition, and are in reasonable agreement with those calculated using a model that accounts for the nonlinearity of the spontaneous and piezoelectric polarizations as functions of Al composition. Our results yield an explicit expression for polarization charge as a function of Al composition at an AlxGa1−xN/GaN interface. © 2002 American Institute of Physics.
Show PACS
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
77.65.Ly Strain-induced piezoelectric fields
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.22.Ej Polarization and depolarization
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Abnormal dependence of contact resistivity on hole concentration in nonalloyed ohmic contacts to p-GaN

Joon Seop Kwak, Ok-Hyun Nam, and Yongjo Park

Appl. Phys. Lett. 80, 3554 (2002); http://dx.doi.org/10.1063/1.1478154 (3 pages) | Cited 30 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The dependence of contact resistivity on hole concentration has been investigated for nonalloyed Pd contacts to p-GaN. The hole concentration was varied by changing the Mg concentration, [Mg], in p-GaN. The p-GaN having the [Mg] of 4.5×1019 cm−3 showed the hole concentration of 2.2×1017 cm−3, where contact resistivity was measured as 8.9×10−2 Ω cm2. When the [Mg] increased to 1.0×1020 cm−3, the hole concentration was significantly reduced to 2.0×1016 cm−3. Nevertheless, the Pd contacts on the p-GaN displayed contact resistivity as low as 5.5×10−4 Ω cm2. The abnormal dependence of contact resistivity on hole concentration may be explained by predominant current flow at the Pd/p-GaN interface through a deep level defect band, rather than the valence band. © 2002 American Institute of Physics.
Show PACS
73.40.Ns Metal-nonmetal contacts
73.40.Cg Contact resistance, contact potential
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.61.Ey III-V semiconductors
73.61.At Metal and metallic alloys

Hall mobility enhancement caused by annealing of Si0.2Ge0.8/Si0.7Ge0.3/Si(001) p-type modulation-doped heterostructures

M. Myronov, P. J. Phillips, T. E. Whall, and E. H. C. Parker

Appl. Phys. Lett. 80, 3557 (2002); http://dx.doi.org/10.1063/1.1478779 (3 pages) | Cited 6 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effect of post-growth furnace thermal annealing (FTA) on the Hall mobility and sheet carrier density measured at 9–300 K in the Si0.2Ge0.8/Si0.7Ge0.3/Si(001) p-type modulation-doped heterostructures was studied. FTA treatments in the temperature range of 600–900 °C for 30 min were performed on similar heterostructures but with two Si0.2Ge0.8 channel thicknesses. The annealing at 600 °C is seen to have a negligible effect on the Hall mobility as well as on the sheet carrier density. Increases in the annealing temperature resulted in pronounced successive increases of the mobility. For both samples the maximum Hall mobility was observed after FTA at 750 °C. Further increases of the annealing temperature resulted in a decrease in mobility. The sheet carrier density showed the opposite behavior with an increase in annealing temperature. The mechanism causing this behavior is discussed. Structural characterization of as-grown and annealed samples was done by cross-sectional transmission electron microscopy. © 2002 American Institute of Physics.
Show PACS
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
81.05.Hd Other semiconductors
72.20.My Galvanomagnetic and other magnetotransport effects
72.20.Fr Low-field transport and mobility; piezoresistance
81.05.Cy Elemental semiconductors
72.20.Ee Mobility edges; hopping transport
61.72.Cc Kinetics of defect formation and annealing
68.37.Lp Transmission electron microscopy (TEM)

Dislocation-free formation of relaxed SiGe-on-insulator layers

T. Tezuka, N. Sugiyama, S. Takagi, and T. Kawakubo

Appl. Phys. Lett. 80, 3560 (2002); http://dx.doi.org/10.1063/1.1479457 (3 pages) | Cited 15 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate the fabrication of dislocation-free strain-relaxed SiGe-on-insulator (SGOI) layers as virtual substrates for strained Si-on-insulator (SOI) metal–oxide–semiconductor field-effect transistors (MOSFETs) by forming SiGe-mesa structures and successive oxidation. A pseudomorphic Si0.9Ge0.1 layer on a SOI layer was etched to form mesa structures. After the oxidation of the mesas, thin (<100 nm) Si0.85Ge0.15 mesa structures were formed on the buried oxide layer. It was found that the mesas with a diameter smaller than 3 μm were almost completely relaxed after oxidation at 1200 °C, without generating any threading dislocations and crosshatch patterns, which generally exist in the relaxed SiGe layers on bulk Si substrates. The formation of SGOI mesas before oxidation has the potential to provide ideal SGOI virtual substrates for strained SOI MOSFETs. © 2002 American Institute of Physics.
Show PACS
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
81.65.Mq Oxidation
85.30.Tv Field effect devices
back to top
RSS Feeds

In situ growth of superconducting MgB2 thin films with preferential orientation by molecular-beam epitaxy

W. Jo, J-U. Huh, T. Ohnishi, A. F. Marshall, M. R. Beasley, and R. H. Hammond

Appl. Phys. Lett. 80, 3563 (2002); http://dx.doi.org/10.1063/1.1478151 (3 pages) | Cited 66 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the synthesis of superconducting MgB2 thin films grown in situ by molecular-beam epitaxy. Mg-rich fluxes are deposited with B flux by electron-beam evaporation onto c-plane sapphire substrates. The films exhibit c-axis oriented peaks of MgB2, and a full width at half maximum of 3° in their rocking curves. In-plane alignment of MgB2 shows 12-fold symmetry, which is observed by the selected area diffraction pattern in transmission electron microscopy. The MgB2 films show a superconducting transition at 34.5 K with ΔTc<1 K. Even though the residual resistivity of the films is quite high (∼60 μΩ cm), the normal-state resistivity has a very similar temperature dependence but is five times larger than that of a single crystal, implying that conduction through the whole sample is imperfectly connected or inhomogeneous. Upper critical fields are obtained from measurement of the field dependence of the resistivity. It is estimated that the upper critical field at 20 K is more than 15 T, which is one of the largest values ever reported. © 2002 American Institute of Physics.
Show PACS
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.A- Nucleation and growth
74.72.-h Cuprate superconductors
74.78.-w Superconducting films and low-dimensional structures
68.55.-a Thin film structure and morphology
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
68.37.Lp Transmission electron microscopy (TEM)
74.25.Op Mixed states, critical fields, and surface sheaths
74.25.F- Transport properties
74.10.+v Occurrence, potential candidates
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition

Strong reduction of thermally activated flux jump rate in superconducting thin films by nanodot-induced pinning centers

A. Crisan, P. Badica, S. Fujiwara, J. C. Nie, A. Sundaresan, Y. Tanaka, and H. Ihara

Appl. Phys. Lett. 80, 3566 (2002); http://dx.doi.org/10.1063/1.1478782 (3 pages) | Cited 15 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
From frequency-dependent ac susceptibility studies of (Cu,T1)BaSrCa2Cu3Oy superconducting thin films, with and without nanodot-induced artificial pinning centers, we estimated the activation energy of flux jumps. The result was that, in the film with nanodots, the pinning potential is several times higher, leading to a probability of thermally activated flux jumps several orders of magnitude lower than in the film without artificial pinning centers. We suggest that our no cost straightforward method for creating extended defects can be successfully employed for the reduction of thermal noise in superconducting electronic devices. © 2002 American Institute of Physics.
Show PACS
74.72.-h Cuprate superconductors
74.78.-w Superconducting films and low-dimensional structures
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
61.72.Nn Stacking faults and other planar or extended defects
74.25.Ha Magnetic properties including vortex structures and related phenomena
68.65.Hb Quantum dots (patterned in quantum wells)

Properties of superconducting MgB2 single crystal grown by a modified flux method

Yong Chan Cho, Sang Eon Park, Se-Young Jeong, Chae-Ryong Cho, Bong Jun Kim, Young Cheol Kim, and Hwa Shik Youn

Appl. Phys. Lett. 80, 3569 (2002); http://dx.doi.org/10.1063/1.1479198 (3 pages) | Cited 2 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the growth of MgB2 single crystals with a large thickness of about 100 μm and a clear hexagonal prismatic morphology. On the low-field magnetization curve M(T), a superconducting transition was observed at 39 K. Using the x-ray diffractometer equipped with a microprobe, we obtained Laue patterns of MgB2 single crystal from a piece of the grown crystal and investigated the impurities introduced during the growing process using Auger electron spectroscopy. © 2002 American Institute of Physics.
Show PACS
74.72.-h Cuprate superconductors
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
74.25.Ha Magnetic properties including vortex structures and related phenomena
81.10.Fq Growth from melts; zone melting and refining
74.10.+v Occurrence, potential candidates
79.20.Fv Electron impact: Auger emission
back to top
RSS Feeds

High-piezoelectric behavior of c-axis-oriented lead zirconate titanate thin films with composition near the morphotropic phase boundary

Desheng Fu, Hisao Suzuki, Takeshi Ogawa, and Kenji Ishikawa

Appl. Phys. Lett. 80, 3572 (2002); http://dx.doi.org/10.1063/1.1477619 (3 pages) | Cited 19 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The piezoelectric responses of c-axis-oriented Pb(Zr0.53Ti0.47)O3 (PZT) thin films have been studied by measuring the stress-induced charge with an accurate charge integrator. These measurements reveal that the c-axis-oriented PZT films have high values of d33, which are several times those of ceramic materials. The intrinsic d33 values of poled films are about 680 and 800 pC/N for the c-axis-oriented films on Si and MgO single-crystal substrates, respectively. It shows that the thin-film deposition technique opens an approach for exploring the potential superior properties of PZT near the morphotropic phase boundary. © 2002 American Institute of Physics.
Show PACS
77.65.Bn Piezoelectric and electrostrictive constants
77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
77.80.B- Phase transitions and Curie point
68.55.-a Thin film structure and morphology
77.22.Ej Polarization and depolarization

Water absorption and interface reactivity of yttrium oxide gate dielectrics on silicon

D. Niu, R. W. Ashcraft, and G. N. Parsons

Appl. Phys. Lett. 80, 3575 (2002); http://dx.doi.org/10.1063/1.1477268 (3 pages) | Cited 28 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High dielectric constant insulators deposited at low temperatures rapidly absorb water during exposure to the atmosphere, and the resulting OH leads to detrimental interface reactions. We report the effect of atmospheric exposure on ultrathin yttrium oxide, and details of silicon substrate reactions during postdeposition anneals. Infrared absorption analysis indicates significant absorption of water vapor during atmospheric exposure, even for very short times (<15 min). X-ray photoelectron spectroscopy demonstrates that after OH absorption, a thermally activated interface reaction proceeds with an activation energy of 0.33 eV, consistent with substrate reaction with OH present in the film. The OH absorption rate is reduced for annealed films or when capping layers are deposited in situ. Similar oxidation processes are expected to occur in other high-k materials of interest, where the rate of OH absorption will depend on the deposition process and material thermal history. © 2002 American Institute of Physics.
Show PACS
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
81.65.Mq Oxidation
77.55.-g Dielectric thin films
78.30.Hv Other nonmetallic inorganics
79.60.Dp Adsorbed layers and thin films
79.60.Jv Interfaces; heterostructures; nanostructures
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics

Enhanced dielectric properties of low-temperature sintered SrBi2Nb2O9/Ag composites

Can Wang, Q. F. Fang, and Z. G. Zhu

Appl. Phys. Lett. 80, 3578 (2002); http://dx.doi.org/10.1063/1.1477616 (3 pages) | Cited 13 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Strontium bismuth niobate (SBN) matrix composites containing Ag particles were prepared by the conventional solid-state reaction method. With the addition of Ag particles to the SBN matrix, the single-phase layered perovskite structure of the matrix was preserved and the sintering temperature of the system was lowered about 200 °C compared with monolithic SBN. The SBN/Ag composites showed a significant increase of the dielectric constant and the loss tangent of SBN/Ag composites decreased in certain Ag content. With increasing Ag content, a gradual increase of the dielectric constant was observed in the temperature range from room temperature to 600 °C. The Curie temperature was found to decrease from 439 °C for the monolithic SBN to 435 °C for the composite with 3.5 vol % Ag, and then with increasing Ag content, the Curie temperature gradually increased to 445 °C for the composite with 14 vol % Ag. The results show that the SBN/Ag composites have enhanced dielectric properties and an improved processing condition, which could be further exploited in capacitor applications. © 2002 American Institute of Physics.
Show PACS
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.22.Ch Permittivity (dielectric function)
77.22.Gm Dielectric loss and relaxation
77.80.B- Phase transitions and Curie point
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)

Large nonlinear dielectric properties of artificial BaTiO3/SrTiO3 superlattices

Juho Kim, Youngnam Kim, Young Sung Kim, Jaichan Lee, Leejun Kim, and Donggeun Jung

Appl. Phys. Lett. 80, 3581 (2002); http://dx.doi.org/10.1063/1.1477934 (3 pages) | Cited 76 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
BaTiO3(BTO)/SrTiO3(STO) artificial superlattices have been made on MgO (100) substrates. The periodicity of the BTO/STO layers in the superlattice was varied from one-unit cell to 125-unit cell thickness. The dielectric constant and its nonlinearity (or voltage tunability) showed similar behavior as the periodicity was varied. The voltage tunability of the superlattice increased with decreasing stacking periodicity of the BTO/STO within the critical thickness. Similarly, the lattice distortion, i.e., the ratio of the lattice parameter along surface normal to parallel, of the BTO and STO layers increased with decreasing the periodicity. Remarkable enhancement of the voltage tunability has been achieved. The superlattice exhibited large voltage tunability (94%, the highest value to date) at the periodicity of BTO2-unit cell/STO2-unit cell at which the maximum lattice distortion of each layer was obtained. This suggests that the nonlinear dielectric property of the superlattice is closely related with the lattice distortion of the individual layers. © 2002 American Institute of Physics.
Show PACS
77.55.-g Dielectric thin films
68.65.Cd Superlattices
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.80.-e Ferroelectricity and antiferroelectricity
77.22.Ch Permittivity (dielectric function)
77.22.Ej Polarization and depolarization

Evolution of Rayleigh constant in fatigued lead zirconate titanate capacitors

J. L. Sun, J. Chen, X. J. Meng, J. Yu, L. X. Bo, S. L. Guo, and J. H. Chu

Appl. Phys. Lett. 80, 3584 (2002); http://dx.doi.org/10.1063/1.1478781 (3 pages) | Cited 7 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The capacitance of Pt/PbZr0.5Ti0.5O3/Pt capacitors versus the strength of applied ac electric field E has been measured for samples that fatigued at different square pulse switching cycles. Based on the in-series capacitor model, the variation of interface capacitance and bulk ferroelectric capacitance at different stages of fatigue were treated separately. A simplified method was derived to calculate the initial dielectric constant and Rayleigh constant for the bulk ferroelectric film from the ac electric field dependence of the sample capacitance. It was found that the initial dielectric constant and Rayleigh constant for the bulk ferroelectric film changed a little when the number of cycles is less than 3×106, whereas it decreased remarkably when the number of cycles is greater than 3×106. The suppression of polarization was attributed to pinning of the domain walls at the electrode/ferroelectric interface. © 2002 American Institute of Physics.
Show PACS
77.22.Ch Permittivity (dielectric function)
84.32.Tt Capacitors
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
77.80.Dj Domain structure; hysteresis
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
77.55.-g Dielectric thin films

Water-induced degradation in lead zirconate titanate piezoelectric ceramics

W. P. Chen, H. L. W. Chan, F. C. H. Yiu, K. M. W. Ng, and P. C. K. Liu

Appl. Phys. Lett. 80, 3587 (2002); http://dx.doi.org/10.1063/1.1479205 (3 pages) | Cited 17 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Water-induced degradation in lead zirconate titanate (PZT) piezoelectric ceramics was studied by a comparison experiment. In one treatment, PZT rings were immersed in a 0.01 M NaOH solution for long periods of time; in the other treatment, PZT rings were placed in a 0.01 M NaOH solution and hydrogen was evolved onto their silver electrodes by the electrolysis of water. No degradation occurred to samples immersed in the NaOH solution; but for the samples that were also treated by electrolysis of water, serious degradation occurred as their mechanical quality factor decreased dramatically and their dielectric loss increased considerably. I–V measurement showed that the resistance decreased greatly in the degraded samples, which could be explained by the formation of charge carriers due to the reduction reaction of atomic hydrogen from the electrolysis of water. It was proposed that the reduction reaction of atomic hydrogen at ambient temperature is an important origin for the degradation of piezoelectric ceramic devices. © 2002 American Institute of Physics.
Show PACS
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
81.65.-b Surface treatments
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
77.65.-j Piezoelectricity and electromechanical effects
77.22.Gm Dielectric loss and relaxation
77.22.Ej Polarization and depolarization

Raman characterization of boron carbonitride nanotubes

C. Y. Zhi, X. D. Bai, and E. G. Wang

Appl. Phys. Lett. 80, 3590 (2002); http://dx.doi.org/10.1063/1.1479207 (3 pages) | Cited 27 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A systematic Raman study of boron carbonitride (BCN) nanotubes, synthesized by bias-assisted hot filament chemical vapor deposition, is reported. Raman spectra up to the fourth order are observed from the BCN nanotubes. Comparing with pure carbon nanotubes, the Raman bands in BCN nanotubes are broadened and the relative intensity of the D mode with respect to the G mode varies with increasing B and N atomic concentrations. The underlying mechanism has been studied on the basis of the microstructures obtained by high-resolution transmission electron microscopy. © 2002 American Institute of Physics.
Show PACS
61.46.-w Structure of nanoscale materials
78.67.Ch Nanotubes
78.30.Na Fullerenes and related materials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Correlation between internal stress and ferroelectric fatigue in Bi4−xLaxTi3O12 thin films

Jung-Kun Lee, Chang-Hoon Kim, Hee-Sang Suh, and Kug-Sun Hong

Appl. Phys. Lett. 80, 3593 (2002); http://dx.doi.org/10.1063/1.1477272 (3 pages) | Cited 62 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
La-substituted bismuth titanate [Bi4−xLaxTi3O12(BLT)] films were synthesized using pulsed-laser deposition and ferroelectric fatigue phenomenon was investigated. The internal strain present in the films, which was analyzed through the evaluation of the x-ray diffraction peak, was partially responsible for the fatigue in BLT films. When x ≥ 0.75, the change in the internal strain was saturated and there was no significant degradation of switching charge, at least up to 1010 cycles. It revealed that the internal strain, as well as chemical stability of oxygen ions, contributed to the ferroelectric fatigue of the BLT films. The origin of the internal strain is discussed in terms of the lattice mismatch between bulk materials and thin films. © 2002 American Institute of Physics.
Show PACS
77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
68.60.Bs Mechanical and acoustical properties
77.22.Ej Polarization and depolarization
77.80.-e Ferroelectricity and antiferroelectricity

Sensitivity in extracting static dielectric constants from multiple film stacks

A. H. Mueller, N. A. Suvorova, and E. A. Irene

Appl. Phys. Lett. 80, 3596 (2002); http://dx.doi.org/10.1063/1.1478159 (3 pages) | Cited 1 time

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This study points out that there is a hyperbolic relationship between the static dielectric constants (Ks) in a dielectric film stack. It is shown using experimental data that this relationship renders K values that are extracted from capacitance–voltage measurements very sensitive to the other input values such as dielectric constants and film thicknesses. Errors as large as 100% and larger can be made in K from small changes in the input parameters. Thus there is a requirement for accurate film thicknesses and a specific knowledge of the nature of interface film(s) and dielectric properties are necessary for accurate K determinations. © 2002 American Institute of Physics.
Show PACS
77.55.-g Dielectric thin films
77.22.Ch Permittivity (dielectric function)
77.84.-s Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials

Low-temperature integration of lead-based ferroelectric capacitors on Si with diffusion barrier layer

B. T. Liu, K. Maki, S. Aggarwal, B. Nagaraj, V. Nagarajan, L. Salamanca-Riba, R. Ramesh, A. M. Dhote, and O. Auciello

Appl. Phys. Lett. 80, 3599 (2002); http://dx.doi.org/10.1063/1.1477281 (3 pages) | Cited 20 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ferroelectric lead zirconate titanate thin films have been integrated on silicon substrates using Ti–Al-based conducting diffusion barriers produced by sputter deposition. The microstructure of the Ti–Al barrier layer was systematically altered through changes in the sputtering conditions, specifically the power density and deposition pressure. We find that the crystallinity of the Ti–Al film strongly correlates with sputtering power density and ambient i.e., it is amorphous at low power density and/or high deposition pressure, and polycrystalline at high power density and/or low deposition pressure. Electron energy loss spectroscopy studies demonstrate that the amorphous Ti–Al (a-Ti–Al) films contain a higher concentration of dissolved oxygen than crystalline Ti–Al. A low temperature sol–gel process has been used to prepare Pb(Zr,Ti)O3 PZT films at 450 °C on conducting Si wafers with a-Ti–Al conducting barrier layer and La–Sr–Co–O top and bottom electrodes. The excellent ferroelectric properties obtained with the a-Ti–Al barrier provide a promising approach for integration of PZT-based capacitors with silicon transistor technology for the fabrication of nonvolatile ferroelectric memories. © 2002 American Institute of Physics.
Show PACS
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
84.32.Tt Capacitors
85.50.Gk Non-volatile ferroelectric memories
77.55.-g Dielectric thin films
77.80.-e Ferroelectricity and antiferroelectricity
81.15.Cd Deposition by sputtering
85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology
81.10.Dn Growth from solutions
81.10.Fq Growth from melts; zone melting and refining
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
79.20.Uv Electron energy loss spectroscopy
back to top
RSS Feeds

Electron field emission from boron-nitride nanofilms

Takashi Sugino, Chiharu Kimura, and Tomohide Yamamoto

Appl. Phys. Lett. 80, 3602 (2002); http://dx.doi.org/10.1063/1.1477622 (3 pages) | Cited 46 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Hexagonal polycrystalline boron-nitride (BN) films are synthesized on Si substrates by plasma-assisted chemical-vapor deposition. In the case of BN films thicker than 20 nm, the turn-on electric field of the electron emission decreases with increasing surface roughness. On the other hand, in the case of BN film as thin as 8–10 nm, it is found that the turn-on electric field is reduced to 8.3 V/μm in spite of the surface of the BN nanofilm being flat, as well as the Si substrate. The Fowler–Nordheim (FN) plot of the field-emission characteristics of the BN nanofilm indicates a straight line, suggesting the presence of FN tunneling. This finding means that introduction of the BN nanofilm leads to a significant reduction in the effective potential barrier height. © 2002 American Institute of Physics.
Show PACS
79.70.+q Field emission, ionization, evaporation, and desorption
68.55.-a Thin film structure and morphology
68.35.B- Structure of clean surfaces (and surface reconstruction)
73.20.At Surface states, band structure, electron density of states
68.37.Ps Atomic force microscopy (AFM)

Photoluminescence properties of Eu3+-doped ZnS nanocrystals prepared in a water/methanol solution

S. C. Qu, W. H. Zhou, F. Q. Liu, N. F. Chen, Z. G. Wang, H. Y. Pan, and D. P. Yu

Appl. Phys. Lett. 80, 3605 (2002); http://dx.doi.org/10.1063/1.1478152 (3 pages) | Cited 38 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Monodispersed ZnS and Eu3+-doped ZnS nanocrystals have been prepared through the co-precipitation reaction of inorganic precursors ZnCl2, EuCl3, and Na2S in a water/methanol binary solution. The mean particle sizes are about 3–5 nm. The structures of the as-prepared ZnS nanoparticles are cubic (zinc blende) as demonstrated by an x-ray powder diffraction. Photoluminescence studies showed a stable room temperature emission in the visible spectrum region for all the samples, with a broadening in the emission band and, in particular, a partially overlapped twin peak in the Eu3+-doped ZnS nanocrystals. The experimental results also indicated that Eu3+-doped ZnS nanocrystals, prepared by controlling synthetic conditions, were stable. © 2002 American Institute of Physics.
Show PACS
78.55.Et II-VI semiconductors
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
61.46.-w Structure of nanoscale materials
61.72.uj III-V and II-VI semiconductors
81.07.Bc Nanocrystalline materials
81.10.Dn Growth from solutions

Cerium-ion-doped yttrium aluminum garnet nanophosphors prepared through sol-gel pyrolysis for luminescent lighting

Chung-Hsin Lu and R. Jagannathan

Appl. Phys. Lett. 80, 3608 (2002); http://dx.doi.org/10.1063/1.1475772 (3 pages) | Cited 39 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Luminescent Y3Al5O12: Ce3+ [yttrium aluminum garnet (YAG):Ce3+] nanoceramics (5–50 nm) have been prepared through a facile sol-gel pyrolysis route. A blueshift of about 720 cm−1 in the reflectance spectra near the absorption edge can be observed for YAG:Ce3+ nanoparticles (having an average particle size around 5 nm) with respect to the submicron powders (∼0.9 μm). Furthermore, the scope of application for this important luminescent system can be extended by isostructural substitution with heavier cations such as Ba2+. This substitution giving rise to an oxygen-vacancy defect complex, that exhibits certain size-sensitive exciton-impurity energy-transfer property in YAG:Ce3+ nanoparticles. © 2002 American Institute of Physics.
Show PACS
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
81.10.Dn Growth from solutions
81.10.Fq Growth from melts; zone melting and refining
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
61.46.-w Structure of nanoscale materials
75.50.Gg Ferrimagnetics
78.55.Hx Other solid inorganic materials
61.72.Yx Interaction between different crystal defects; gettering effect
71.35.-y Excitons and related phenomena

Synthesis of boron nitride nanowires

K. F. Huo, Z. Hu, F. Chen, J. J. Fu, Y. Chen, B. H. Liu, J. Ding, Z. L. Dong, and T. White

Appl. Phys. Lett. 80, 3611 (2002); http://dx.doi.org/10.1063/1.1479213 (3 pages) | Cited 29 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A chemical method has been developed for synthesizing boron nitride nanowires through the reaction of a mixture gas of nitrogen (N2) and ammonia (NH3) over nanoscale α-FeB particles at 1100 °C. Boron content in the product comes from the α-FeB catalyst itself. Transmission electron microscopic image indicates an abundant quantity of BN nanowires with diameter about 20 nm and length up to several tens of microns. The product has also been characterized by high-resolution electron microscopy and electron energy loss spectrometer. The perfectly straight lattice fringes with an interlayer spacing of about 0.333 nm corresponding to d0002 spacing of h-BN indicate that the BN nanowires are well crystallized. Also, a growth mechanism has been speculated. © 2002 American Institute of Physics.
Show PACS
68.65.La Quantum wires (patterned in quantum wells)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
79.20.Uv Electron energy loss spectroscopy
68.37.Lp Transmission electron microscopy (TEM)
61.46.-w Structure of nanoscale materials

Nanoembossing of thermoplastic polymers for microfluidic applications

V. Studer, A. Pépin, and Y. Chen

Appl. Phys. Lett. 80, 3614 (2002); http://dx.doi.org/10.1063/1.1479202 (3 pages) | Cited 35 times

Online Publication Date: 7 May 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a method for the fabrication of plastic microfluidic devices based on nanoembossing and thermal bonding. By nanoembossing of thermoplastic polymer pellets, both microfluidic deep channels and high resolution features can be formed using a silicon mold fabricated by electron beam lithography and reactive ion etching. By thermal bonding with another plastic sheet, the fabricated microfluidic devices can be sealed without clogging. Observation of pressure driven and electrokinetic flows through high density pillar arrays indicates the feasibility of nanofluidic analysis using plastic devices. © 2002 American Institute of Physics.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
81.16.Nd Micro- and nanolithography
47.85.Np Fluidics
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.65.Cf Surface cleaning, etching, patterning
81.10.Fq Growth from melts; zone melting and refining
Page 2 of 3 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close