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

17 Aug 1998

Volume 73, Issue 7, pp. 865-1010

Page 1 of 2 Pages Next Page | Jump to Page
back to top
RSS Feeds

Domain broadening in quasi-phase-matched nonlinear optical devices

G. Rosenman, Kh. Garb, A. Skliar, M. Oron, D. Eger, and M. Katz

Appl. Phys. Lett. 73, 865 (1998); http://dx.doi.org/10.1063/1.121969 (3 pages) | Cited 34 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Dominant factors influencing domain broadening in periodically poled ferroelectric domain structures for quasi-phase-matched nonlinear optical converters are studied. It is shown that fabricated patterned switching electrode gives rise to a high tangential field causing polarization inversion behind an isolated layer of the patterned electrode. The domain broadening depends on basic electron parameters of a ferroelectric crystal such as surface electron concentration and electron mobility. © 1998 American Institute of Physics.
Show PACS
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.Nv Optical frequency converters
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
42.86.+b Optical workshop techniques
77.22.Ej Polarization and depolarization
77.80.Dj Domain structure; hysteresis

Modeling the optical properties of hexagonal GaN

Aleksandra B. Djurišić and E. Herbert Li

Appl. Phys. Lett. 73, 868 (1998); http://dx.doi.org/10.1063/1.121970 (3 pages) | Cited 11 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An adjustable broadening function instead of the conventional Lorentzian one is incorporated in the dielectric function model for hexagonal GaN. One-electron contributions at E1 critical points and higher-state (m>1) exciton terms, which were incorrectly disregarded in the previous study, are taken into account. Model parameters were determined using the acceptance-probability-controlled simulated annealing. As a result, excellent agreement with experimental data for both real and imaginary parts in the range from 1.5 to 10 eV is obtained. Average discrepancy between experimental and calculated data for the real part of the index of refraction equals 2.75×10−4, and for the imaginary part is 1.66×10−3. © 1998 American Institute of Physics.
Show PACS
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
42.25.-p Wave optics
71.35.-y Excitons and related phenomena

Photon generation by silicon diodes in avalanche breakdown

N. Akil, S. E. Kerns, D. V. Kerns, A. Hoffmann, and J-P. Charles

Appl. Phys. Lett. 73, 871 (1998); http://dx.doi.org/10.1063/1.121971 (2 pages) | Cited 15 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Light emission from a p-n diode biased in controlled avalanche breakdown has been measured over the photon energy range 1.4–3.4 eV. Previously published models are compared with measured data to associate specific mechanisms with avalanche photon emission in silicon. A multimechanism model fitting the measured spectrum is presented. © 1998 American Institute of Physics.
Show PACS
85.60.Dw Photodiodes; phototransistors; photoresistors
85.30.De Semiconductor-device characterization, design, and modeling
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
77.22.Jp Dielectric breakdown and space-charge effects
72.20.Ht High-field and nonlinear effects

Ultrafast generation of blue light by efficient second-harmonic generation in periodically-poled bulk and waveguide potassium titanyl phosphate

Y. Wang, V. Petrov, Y. J. Ding, Y. Zheng, J. B. Khurgin, and W. P. Risk

Appl. Phys. Lett. 73, 873 (1998); http://dx.doi.org/10.1063/1.121972 (3 pages) | Cited 8 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated second-harmonic generation in short-period periodically-poled bulk and waveguide potassium titanyl phosphate crystals to generate blue light using subpicosecond laser pulses. For the bulk, the highest conversion efficiency is ≈ 5.5%, which is about two orders of magnitude larger than that achieved previously. For the waveguide, the highest conversion efficiency is ≈ 32%, which is about a factor of 4 higher than that obtained before. These measured values are in good agreement with our theoretical results. We have observed saturation of conversion efficiency, which sets a limit to the maximum efficiency that can be achieved. © 1998 American Institute of Physics.
Show PACS
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.79.Nv Optical frequency converters
78.47.-p Spectroscopy of solid state dynamics
42.65.Wi Nonlinear waveguides
42.79.Gn Optical waveguides and couplers

Coherent control of optical gain from electronic intersubband transitions in semiconductors

Xuedong Hu and Walter Pötz

Appl. Phys. Lett. 73, 876 (1998); http://dx.doi.org/10.1063/1.121973 (3 pages) | Cited 9 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study electronic transitions between a subband and a lower subband doublet which is driven by a coherent microwave (MW) field in a semiconductor double well structure. Within a microscopic three-band model, we show that variation of the MW phase allows manipulation of the optical gain provided the probe pulse duration is shorter than the period of the MW-field-generated interband polarization in the doublet. Moreover, we find that optical gain without inversion can be achieved in spite of subpicosecond dissipative mechanisms provided by electron-phonon coupling and electron tunneling into and out of the double well. © 1998 American Institute of Physics.
Show PACS
78.66.-w Optical properties of specific thin films
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
42.55.Px Semiconductor lasers; laser diodes
73.40.Gk Tunneling
71.38.-k Polarons and electron-phonon interactions

Energy transfer from a naphthalimide functionalized side chain polymer towards DCM used as a dopant molecule

C.-M. Bouché, P. Le Barny, H. Facoetti, and P. Robin

Appl. Phys. Lett. 73, 879 (1998); http://dx.doi.org/10.1063/1.122025 (3 pages) | Cited 2 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The influence of the introduction of a dopant molecule, namely DCM, in a matrix of a naphthalimide derived polymer (PNI) is studied by means of UV-visible absorption spectroscopy, photoluminescence emission and excitation spectrometry, and 2D photoluminescence spectrometry. We demonstrate that, contrary to previous observations on similar systems, energy transfer occurs between PNI and DCM. Moreover, photoluminescent (PL) and electroluminescent (EL) emissions are assigned to arise from the same excited state. © 1998 American Institute of Physics.
Show PACS
78.55.Kz Solid organic materials
42.70.Jk Polymers and organics
78.60.Fi Electroluminescence
78.40.Me Organic compounds and polymers
back to top
RSS Feeds

Transverse surface acoustic wave detection by scanning acoustic force microscopy

G. Behme, T. Hesjedal, E. Chilla, and H.-J. Fröhlich

Appl. Phys. Lett. 73, 882 (1998); http://dx.doi.org/10.1063/1.122026 (3 pages) | Cited 12 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a scanning acoustic force microscope (SAFM) for the study of surface acoustic wave (SAW) phenomena on the submicron lateral scale. Until now, SAWs with in-plane oscillation components could only be studied effectively via nonvanishing out-of-plane oscillation contributions. By operating the microscope in lateral force mode, where both bending and torsion of the cantilever are detected, additional amplitude-dependent signals are found, which are due to the interaction with purely in-plane polarized surface oscillations. To demonstrate the capabilities of this type of SAFM, Love waves were studied on the surface of layers deposited on ST-cut quartz with SAW propagation perpendicular to the crystal X-axis. The phase velocity of the wave as well as the amplitude of a standing wave field was measured and compared to calculated values. © 1998 American Institute of Physics.
Show PACS
68.35.Gy Mechanical properties; surface strains
43.58.Ls Acoustical lenses and microscopes
07.79.Lh Atomic force microscopes
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
62.30.+d Mechanical and elastic waves; vibrations
62.65.+k Acoustical properties of solids
back to top
RSS Feeds

Generation of intense excimer radiation from high-pressure hollow cathode discharges

Ahmed El-Habachi and Karl H. Schoenbach

Appl. Phys. Lett. 73, 885 (1998); http://dx.doi.org/10.1063/1.122027 (3 pages) | Cited 39 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
By reducing the diameter of the cathode opening in a hollow cathode discharge geometry to values on the order of 100 μm, we were able to operate these discharges in noble gases in a direct current mode up to atmospheric pressure. High-pressure discharges in xenon were found to be strong sources of excimer radiation. Highest intensities at a wavelength of 172 nm were obtained at a pressure of 400 Torr. At this pressure, the vacuum ultraviolet (VUV) radiant power of a single discharge operating at a forward voltage of 220 V and currents exceeding 2 mA reaches values between 6% and 9% of the input electrical power. The possibility to form arrays of these discharges allows the generation of flat panel VUV lamps with radiant emittances exceeding 50 W/cm2. © 1998 American Institute of Physics.
Show PACS
52.80.Hc Glow; corona
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
42.72.Bj Visible and ultraviolet sources
33.20.Ni Vacuum ultraviolet spectra

Experimental evidence for high-yield C74 production in an arc periphery plasma

R. Hatakeyama, T. Hirata, H. Ishida, and N. Sato

Appl. Phys. Lett. 73, 888 (1998); http://dx.doi.org/10.1063/1.122028 (3 pages) | Cited 4 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Spatial profiles and buffer-gas pressure dependences of fullerenes contained in primary carbon soots are measured in order to investigate production ratios of higher fullerenes to C60 in an arc-discharge fullerene generator. It is found that C74 is efficiently produced in the arc periphery-plasma region while C60 is mainly produced in the core-plasma region, being the most dominant higher fullerene under the condition of a higher helium-gas pressure (>100 Torr). © 1998 American Institute of Physics.
Show PACS
61.48.-c Structure of fullerenes and related hollow and planar molecular structures
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
81.05.ub Fullerenes and related materials
back to top
RSS Feeds

Effects of ion irradiation on the residual stresses in Cr thin films

A. Misra, S. Fayeulle, H. Kung, T. E. Mitchell, and M. Nastasi

Appl. Phys. Lett. 73, 891 (1998); http://dx.doi.org/10.1063/1.122029 (3 pages) | Cited 11 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Cr films sputtered onto {100} Si substrates at room temperature were found to be under residual tension, as revealed by wafer curvature measurements. A 150 nm thick Cr film was bombarded with 300 keV Ar ions after deposition. The intrinsic residual tensile stress increased slightly and then decreased with further increase in the ion dose. For ion doses >1×1015 ions/cm2, the stress in the film became compressive and increased with increasing dose. Transmission electron microscopy revealed that the grain boundaries in as-deposited Cr have columnar porosity. A Cr film, ion irradiated to a dose of 5×1015 ions/cm2, showed no grain boundary porosity. The changes in the residual stress during ion irradiation are explained by considering Ar incorporation in the film and the manner in which irradiation may change the interatomic distances and forces. © 1998 American Institute of Physics.
Show PACS
61.80.Jh Ion radiation effects
61.82.Bg Metals and alloys
68.60.Bs Mechanical and acoustical properties
81.15.Cd Deposition by sputtering
61.72.Mm Grain and twin boundaries

Combinatorial synthesis and evaluation of epitaxial ferroelectric device libraries

I. Takeuchi, H. Chang, C. Gao, P. G. Schultz, X.-D. Xiang, R. P. Sharma, M. J. Downes, and T. Venkatesan

Appl. Phys. Lett. 73, 894 (1998); http://dx.doi.org/10.1063/1.122030 (3 pages) | Cited 43 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Combinatorial libraries of parallel-plate capacitors, consisting of Pt and La0.5Sr0.5CoO3 electrodes and a doped BaxSr1−xTiO3 dielectric layer, have been fabricated and analyzed to systematically study the effects of dopants on device performance. Epitaxial heterostructure libraries with sharp interfaces were generated from amorphous layers on LaAlO3 substrates. Two hundred and forty different host/dopant combinations were synthesized on a 1/2 in. by 1/2 in. substrate, with 23 capacitors for each combination. Addition of 1.5 mol % W was found to increase the figure of merit (ϵ/Ileak) 220-fold and reduce the high-frequency (MHz and GHz) loss tangent by fourfold. © 1998 American Institute of Physics.
Show PACS
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
84.32.Tt Capacitors
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates

Improvement in performance of electrically tunable devices based on nonlinear dielectric SrTiO3 using a homoepitaxial LaAlO3 interlayer

Q. X. Jia, A. T. Findikoglu, D. Reagor, and P. Lu

Appl. Phys. Lett. 73, 897 (1998); http://dx.doi.org/10.1063/1.122031 (3 pages) | Cited 35 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Improved structural and dielectric properties of nonlinear dielectric SrTiO3 thin films on LaAlO3 substrates were accomplished by incorporating a homoepitaxial LaAlO3 interlayer between the substrate and the dielectric film. Using this interlayer, the quality factor of SrTiO3 films with high-temperature superconducting YBa2Cu3O7−x electrodes on LaAlO3 substrates was improved by more than 50% at 4.2 GHz and 4 K. This improvement, combined with no change in nonlinearity, led to greater than a 50% enhancement of the finesse factor (defined as the product of the quality factor and the fractional shift resonant frequency) for the coplanar waveguide microwave resonators. The reduced planar defect density in the SrTiO3 films was attributed to this improvement. © 1998 American Institute of Physics.
Show PACS
77.55.-g Dielectric thin films
68.35.Ct Interface structure and roughness
74.72.-h Cuprate superconductors
84.40.Az Waveguides, transmission lines, striplines
61.72.-y Defects and impurities in crystals; microstructure
68.55.-a Thin film structure and morphology
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Mechanism of low temperature C54 TiSi2 formation bypassing C49 TiSi2: Effect of Si microstructure and Mo impurities on the Ti–Si reaction path

J. A. Kittl, M. A. Gribelyuk, and S. B. Samavedam

Appl. Phys. Lett. 73, 900 (1998); http://dx.doi.org/10.1063/1.122032 (3 pages) | Cited 22 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
X-ray diffraction, high resolution transmission electron microscopy, and resistivity measurements were used to demonstrate a modification of the Ti/Si reaction path consisting of direct nucleation followed by diffusion limited growth of low resistivity C54 TiSi2 without nucleation of high resistivity C49 TiSi2, for the reaction of Ti with Mo doped polycrystalline or Mo doped amorphous Si by rapid thermal processing at 650 °C. We also report the mechanism of early C54 nucleation. We demonstrate that MoSi2 and an unidentified silicide phase lattice matched to C54 TiSi2, with spacings of 4.15 and 2.26 Å, nucleate along the Ti/Si interface at early stages of the reaction and act as templates on which C54 TiSi2 nucleates and grows epitaxially. In contrast, the conventional phase sequence, nucleation and growth of C49 TiSi2 preceding nucleation of C54 TiSi2, was observed for the Ti/Mo doped single crystal (100) Si reaction and for all samples without Mo. © 1998 American Institute of Physics.
Show PACS
68.35.Fx Diffusion; interface formation
81.05.Cy Elemental semiconductors
81.05.Gc Amorphous semiconductors
66.30.Ny Chemical interdiffusion; diffusion barriers
73.40.Ns Metal-nonmetal contacts

Ferroelectric characterization of highly (0001)-oriented YMnO3 thin films grown by chemical solution deposition

Woo-Chul Yi, Joon-Seon Choe, Chang-Rok Moon, Sook-Il Kwun, and Jong-Gul Yoon

Appl. Phys. Lett. 73, 903 (1998); http://dx.doi.org/10.1063/1.122443 (3 pages) | Cited 42 times

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
Highly (0001)-oriented thin films of YMnO3 were grown directly on Si substrates by chemical solution deposition. The crystallinity of the films was investigated by using x-ray diffraction: θ–2θ scan, rocking curve, and pole figure. Analysis of the x-ray photoelectron spectroscopy data and Rutherford backscattering spectroscopy spectrum showed that the films had a single phase of stoichiometric YMnO3. The ferroelectric properties of YMnO3 were investigated by measuring the temperature dependence of the capacitance–voltage characteristics in the metal/ferroelectric/semiconductor structure. Screening of the ferroelectricity of YMnO3 thin film at room temperature was discussed in conjunction with the charge effects. © 1998 American Institute of Physics.
Show PACS
77.55.-g Dielectric thin films
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.80.-e Ferroelectricity and antiferroelectricity
68.55.-a Thin film structure and morphology
79.60.Dp Adsorbed layers and thin films
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)

Coherent x-ray scattering from an optical grating

Binhua Lin, Mark L. Schlossman, Mati Meron, Scott M. Williams, Zhengqing Huang, and P. James Viccaro

Appl. Phys. Lett. 73, 906 (1998); http://dx.doi.org/10.1063/1.122033 (3 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
X-ray speckles due to scattering of partially (transverse) coherent x rays from an optical reflection grating are observed. The speckles indicate the presence of surface inhomogeneities of the grating that are otherwise undetectable with either visible laser light or transversely incoherent x-ray scattering. Qualitative analysis of the speckle patterns provide information on the surface morphology of the grating. The underlying order due to the periodicity of the grating enhances the detection of the speckles. © 1998 American Institute of Physics.
Show PACS
42.79.Dj Gratings
78.70.Ck X-ray scattering
68.35.B- Structure of clean surfaces (and surface reconstruction)

Recover the phases from intensity data of x-ray diffraction

Gu Xu

Appl. Phys. Lett. 73, 909 (1998); http://dx.doi.org/10.1063/1.122034 (3 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
For many years, people believed that in conventional x-ray crystallography one can only record the scattering intensities but not the phases. In order to study structures at the atomic scale, one has to use multibeam measurement or to rely on additional knowledge such as bonding length and to fit the intensity data by trial structure models. In this letter, however, we show that the phases are in fact hidden in the intensity data and can be recovered by studying the peak shoulders. To demonstrate, the x-ray diffraction data of aluminum powder were used to recover the phases and to reconstruct the electron density map. © 1998 American Institute of Physics.
Show PACS
61.05.C- X-ray diffraction and scattering
61.05.cf X-ray scattering (including small-angle scattering)
78.70.Ck X-ray scattering
61.05.cp X-ray diffraction

Wavelength dependence of 4-dimethylamino-4′-nitrostilbene polymer thin film photodegradation

Qiang Zhang, Michael Canva, and George Stegeman

Appl. Phys. Lett. 73, 912 (1998); http://dx.doi.org/10.1063/1.122035 (3 pages) | Cited 15 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The polymeric electro-optical stilbene material, 4-dimethylamino-4′-nitrostilbene (DANS), was illuminated at wavelengths ranging from the visible to near-infrared in order to quantify its photodegradation processes. Photodegradation due to one-photon and two-photon absorption was studied. The quantum efficiency of the chromophore degradation is found to be strongly wavelength and absorption mechanism dependent. This suggests that, in different regions of the spectrum, different excited states or different mechanisms are involved in the degradation process. In the near-infrared spectral region, operation lifetimes of electro-optic devices made from this chromophore are expected to be around only few hundreds hours, dramatically shorter than it was previously believed. © 1998 American Institute of Physics.
Show PACS
82.50.Bc Processes caused by infrared radiation
82.50.Hp Processes caused by visible and UV light
61.41.+e Polymers, elastomers, and plastics
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
82.35.-x Polymers: properties; reactions; polymerization

Influence of negative dc bias voltage on structural transformation of carbon nitride at 600 °C

Y. K. Yap, S. Kida, T. Aoyama, Y. Mori, and T. Sasaki

Appl. Phys. Lett. 73, 915 (1998); http://dx.doi.org/10.1063/1.122036 (3 pages) | Cited 39 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Carbon nitride (CN) thin films were prepared at 600 °C by rf plasma pulsed laser deposition. As we increased the magnitude of the negative dc bias voltage, the CN bonds were transformed from a mixture of sp2 C–N and sp3 C–N states into a CN phase predominated by tetrahedral CN bonds. A biasing threshold of this transformation occurred due to the annihilation of the graphite microstructure, which coincided with a threshold of significant nitrogen incorporation. We found that suppression of graphite supersaturation appeared to be important for the formation of the tetrahedral sp3 C–N bonds. The nitrogen content of these films is stable upon annealing at 800 °C in vacuum. © 1998 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
81.15.Fg Pulsed laser ablation deposition
64.70.K- Solid-solid transitions
81.40.Gh Other heat and thermomechanical treatments

Field emission from single-wall carbon nanotube films

Jean-Marc Bonard, Jean-Paul Salvetat, Thomas Stöckli, Walt A. de Heer, László Forró, and André Châtelain

Appl. Phys. Lett. 73, 918 (1998); http://dx.doi.org/10.1063/1.122037 (3 pages) | Cited 362 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the field emission properties of single-wall carbon nanotube films, with emphasis on current–versus–voltage (I–V) characteristics and current stability. The films are excellent field emitters, yielding current densities higher than 10 mA cm−2 with operating voltages that are far lower than for other film emitters, but show a significant degradation of their performances with time. The observed deviations from the Fowler-Nordheim behavior in the I–V characteristics point to the presence of a nonmetallic density of states at the tip of the nanotubes. © 1998 American Institute of Physics.
Show PACS
61.46.-w Structure of nanoscale materials
79.70.+q Field emission, ionization, evaporation, and desorption
71.20.Tx Fullerenes and related materials; intercalation compounds

Three-dimensional orientational control of molecules by slantwise photoirradiation

Kunihiro Ichimura, Shin’ya Morino, and Haruhisa Akiyama

Appl. Phys. Lett. 73, 921 (1998); http://dx.doi.org/10.1063/1.122038 (3 pages) | Cited 30 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
When a film of poly[2-(4-phenylazophenyloxy)ethyl methacrylate] is subjected to irradiation with nonpolarized 436 nm light for n-π∗ excitation at an oblique incident angle with respect to a film surface, dichroism is induced as a result of the reorientation of azobenzene chromophores. The orientational direction is determined reversibly by an incident plane of the light while azobenzene residues reorient in a direction parallel with the light propagation. This procedure is applicable to the generation of tilt angles of nematic liquid crystals assisted by obliquely photoirradiated films as a function of exposure doses, maintaining homogeneous alignment during photoirradiation. © 1998 American Institute of Physics.
Show PACS
61.41.+e Polymers, elastomers, and plastics
61.30.Eb Experimental determinations of smectic, nematic, cholesteric, and other structures
78.20.Fm Birefringence

X-ray diffraction analysis of SiGe/Si heterostructures on sapphire substrates

P. M. Mooney, J. A. Ott, J. O. Chu, and J. L. Jordan-Sweet

Appl. Phys. Lett. 73, 924 (1998); http://dx.doi.org/10.1063/1.122039 (3 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Si/Si1−xGex heterostructures on improved silicon-on-sapphire substrates were grown epitaxially by ultrahigh vacuum chemical vapor deposition for application as p-channel field effect transistors. High-resolution triple-axis x-ray diffraction was used to analyze these structures quantitatively and to evaluate their thermal stability. Outdiffusion of Ge from the strained Si1−xGex quantum well was observed after annealing at 850 °C. The amount of outdiffusion was comparable to that observed in Si1−xGex structures on bulk Si wafers. © 1998 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
85.30.Tv Field effect devices
68.60.Dv Thermal stability; thermal effects
61.72.Cc Kinetics of defect formation and annealing
back to top
RSS Feeds

Growth and field dependent dielectric properties of epitaxial Na0.5K0.5NbO3 thin films

Xin Wang, Ulf Helmersson, Sveinn Olafsson, Staffan Rudner, Lars-David Wernlund, and Spartak Gevorgian

Appl. Phys. Lett. 73, 927 (1998); http://dx.doi.org/10.1063/1.122040 (3 pages) | Cited 52 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Na0.5K0.5NbO3 thin films have been grown on LaAlO3(001) substrates using rf magnetron sputtering from a Na and K enriched target. X-ray diffraction showed that the films are epitaxial with mosaic broadening as narrow as 0.044°. Interdigital Au finger electrodes were photolithographically defined on the film surfaces. The dielectric properties of these interdigital capacitors were measured at 1 MHz from room temperature down to 50 K. The capacitor showed 35% tunability at room temperature and a loss tangent of 0.007 without dc bias applied. The loss decreased further with increasing dc bias. For lower temperatures, the capacitance exhibited a broad maximum at ∼ 200 K, which is possibly linked to a phase transformation of the Na0.5K0.5NbO3 film. © 1998 American Institute of Physics.
Show PACS
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
81.15.Cd Deposition by sputtering
77.22.Gm Dielectric loss and relaxation
84.32.Tt Capacitors
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Analysis of composition fluctuations on an atomic scale in Al0.25Ga0.75N by high-resolution transmission electron microscopy

B. Neubauer, A. Rosenauer, D. Gerthsen, O. Ambacher, and M. Stutzmann

Appl. Phys. Lett. 73, 930 (1998); http://dx.doi.org/10.1063/1.122041 (3 pages) | Cited 9 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Composition fluctuations in the Al0.25Ga0.75N layer of an AlGaN/GaN transistor structure grown by plasma induced molecular beam epitaxy on Al2O3(0001) at a growth temperature of 870 °C were studied by digital analysis of lattice images (DALI) of high-resolution transmission electron microscopy (HRTEM) cross-section images. DALI exploits the linear dependence of the lattice parameters on the Al content by applying Vegard’s law. Detecting the distances between intensity maxima positions in the micrograph which can be considered as a fingerprint of the local lattice parameters quantitatively derives composition profiles on an atomic scale. In the HRTEM cross-section image different areas were observed in the Al0.25Ga0.75N layer with either homogeneous or “striped” contrast. In the striped areas the analyses indicate a strong periodic decomposition with a period of 1 nm consisting of 1 ML Al0.8Ga0.2N and about 3 ML Al0.07Ga0.93N. The regions with homogeneous contrast do not exhibit significant composition fluctuations. © 1998 American Institute of Physics.
Show PACS
68.55.Nq Composition and phase identification
61.66.Bi Elemental solids
61.66.Dk Alloys
68.35.Ct Interface structure and roughness

Oxide thickness dependence of energy shifts in the Si 2p levels for the SiO2/Si structure, and its elimination by a palladium overlayer

Hikaru Kobayashi, Tomohiro Kubota, Hidefumi Kawa, Yoshihiro Nakato, and Masayoshi Nishiyama

Appl. Phys. Lett. 73, 933 (1998); http://dx.doi.org/10.1063/1.122042 (3 pages) | Cited 31 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The energy difference between the oxide and substrate Si 2p peaks for silicon oxide/Si structures increases with the oxide thickness. The dependence of the energy shift on the oxide thickness almost disappears with the deposition of a thin palladium overlayer, because of the avoidance of the surface charging effect due to photoemission and because of the nearly constant energy shift resulting from extra atomic relaxation. The true chemical shift of silicon oxide layers thicker than 2 nm is determined to be ∼ 3.8 eV. For the thickness dependence of the oxide Si 2p energy, the extra atomic relaxation and charging effect are dominant for oxide layers thinner than ∼ 2 nm and thicker than ∼ 4 nm, respectively. In the intermediate thickness region, both the effects are important. © 1998 American Institute of Physics.
Show PACS
79.60.Dp Adsorbed layers and thin films
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.20.At Surface states, band structure, electron density of states

Energetics of AlN thin films on the Al2O3(0001) surface

R. Di Felice and J. E. Northrup

Appl. Phys. Lett. 73, 936 (1998); http://dx.doi.org/10.1063/1.122044 (3 pages) | Cited 25 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present an ab initio study of the energetics and atomic structure of films consisting of approximately 1 bilayer of AlN on the c-plane sapphire surface. We show that these films are unstable with respect to three-dimensional islands, and we attribute this instability to both strain and chemical mismatch between the oxide and the nitride. The relative stability of the AlN films depends on the chemical potentials of Al and N. Films having (0001) polarity are expected to form under Al-rich conditions. Films with (0001) polarity appear to form only for undersaturation conditions of bulk AlN in the initial stages of growth. © 1998 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
81.05.Ea III-V semiconductors
65.20.-w Thermal properties of liquids
65.40.gd Entropy
Page 1 of 2 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close