jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

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

1 Nov 2000

Volume 88, Issue 9, pp. 4933-5501

Return to All Sections
back to top
RSS Feeds

Noise characterization of sputtered amorphous carbon films

N. A. Hastas, C. A. Dimitriadis, Y. Panayiotatos, D. H. Tassis, P. Patsalas, and S. Logothetidis

J. Appl. Phys. 88, 5482 (2000); http://dx.doi.org/10.1063/1.1317234 (3 pages) | Cited 11 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Low-frequency noise measurements have been carried out at room temperature in amorphous carbon (α-C) thin films with the current I as the parameter. The α-C films, rich in sp2 bonds, were prepared by rf magnetron sputtering at room temperature. Hall measurements performed at room temperature show that the α-C films are p-type semiconductors with a hole concentration of about 2.8×1018 cm−3. In α-C film grown on oxidized silicon wafer, the current shows an ohmic behavior for low applied voltages, while the conduction mechanism is dominated by the Poole–Frenkel effect for high applied voltages. In the linear voltage region, the power spectral density of the current fluctuations exhibits 1/fγ (with γ<1) behavior and is proportional to I2. Using a noise model based on trapping–detrapping of holes of the valence band and the gap states of exponential energy distribution, the noise data can provide an assessment of the distribution of traps within the band gap of the α-C material. © 2000 American Institute of Physics.
Show PACS
73.61.Jc Amorphous semiconductors; glasses
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.50.Fq High-field and nonlinear effects
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.50.Td Noise processes and phenomena

X-ray photoelectron spectroscopy indication of decomposition species in the residue of shocked polytetrafluoroethylene powder

W. H. Holt, W. Mock, and F. Santiago

J. Appl. Phys. 88, 5485 (2000); http://dx.doi.org/10.1063/1.1314870 (2 pages) | Cited 3 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Forty-eight percent porous polytetrafluoroethylene (PTFE) powder placed inside a steel closed container has been impact shock loaded with a gas gun and soft recovered. The initial stress in the powder is calculated to be 7.2 kbar. The residue in the container showed dark regions where the originally white powder had decomposed to form black soot. X-ray photoelectron spectroscopy (XPS) was used to analyze in situ a portion of a dark region. The resulting spectrum showed a large amorphous carbon peak that was not observed in the unshocked powder spectrum. In addition, the shocked material showed several peaks containing hydrogen and/or oxygen, suggesting reactions of dissociation products with ambient air and/or water vapor in the polymer pores or possibly with residual water in the polymer. (The residual gas analyzer in the XPS system detected water vapor in the unshocked specimen.) Both spectra showed peaks corresponding to the PTFE linear polymer chain F–C–F. © 2000 American Institute of Physics.
Show PACS
82.40.Fp Shock wave initiated reactions, high-pressure chemistry
82.35.-x Polymers: properties; reactions; polymerization
61.41.+e Polymers, elastomers, and plastics
79.60.-i Photoemission and photoelectron spectra
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
62.50.-p High-pressure effects in solids and liquids
81.05.Rm Porous materials; granular materials
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials

How accurate are Stoney’s equation and recent modifications

Claude A. Klein

J. Appl. Phys. 88, 5487 (2000); http://dx.doi.org/10.1063/1.1313776 (3 pages) | Cited 100 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Stoney’s equation has been—and still is—extensively used to evaluate the macrostress acting in a coating deposited on a thick substrate. In principle, the formula applies only in the “thin-film approximation,” that is, for coatings much thinner than the substrate. The main purpose of this communication is to demonstrate that, based on a general theory of elastic interactions in multilayer laminates, the correct formula for the stress can be expressed in terms of Stoney’s equation and a correction factor equal to (1+γ δ3)/(1+δ), where γ designates the ratio of the biaxial moduli and δ is the ratio of the layer thicknesses. In this light, it is shown that (a) Stoney’s equation does not cause serious errors for thickness ratios δ⩽0.1; (b) Atkinson’s recently proposed modification, which does not require information on the coating’s modulus, yields much improved results for thickness ratios up to δ≃0.4; and (c) Brenner–Senderoff-type expressions can be very misleading and should be avoided. © 2000 American Institute of Physics.
Show PACS
68.60.Bs Mechanical and acoustical properties
62.20.D- Elasticity
81.40.Jj Elasticity and anelasticity, stress-strain relations

Ultrahigh transparency of Ni/Au ohmic contacts to surface-treated p-type GaN

Ja-Soon Jang, Seong-Ju Park, and Tae-Yeon Seong

J. Appl. Phys. 88, 5490 (2000); http://dx.doi.org/10.1063/1.1312832 (3 pages) | Cited 10 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on ultrahigh-transparency and low-resistance Ni/Au ohmic contacts to surface-treated p-GaN:Mg (3.6×1017 cm−3). It is shown that annealing at 500 °C for 1 min in a N2 ambient improves ohmic contact properties. Specific contact resistance is measured to be 5.0(±1.0)×10−3 and 2.5(±1.0)×10−3 Ω cm2 for the as-deposited and annealed samples, respectively. It is also shown that the light transmittance is 90.3(±0.6) and 97.3(±0.8) % (at 470 nm) for the as-deposited and annealed contacts, respectively. Furthermore, the surface of the annealed contact is found to be fairly smooth with a root-mean-square roughness of 0.84 nm. These results are compared with those previously reported for the Ni/Au contacts. © 2000 American Institute of Physics.
Show PACS
73.40.Ns Metal-nonmetal contacts
85.40.Ls Metallization, contacts, interconnects; device isolation
78.66.Bz Metals and metallic alloys
81.65.Cf Surface cleaning, etching, patterning
73.40.Cg Contact resistance, contact potential
61.72.Cc Kinetics of defect formation and annealing
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
68.35.B- Structure of clean surfaces (and surface reconstruction)

Polycrystallization and surface erosion of amorphous GaN during elevated temperature ion bombardment

S. O. Kucheyev, J. S. Williams, C. Jagadish, J. Zou, and G. Li

J. Appl. Phys. 88, 5493 (2000); http://dx.doi.org/10.1063/1.1318361 (3 pages) | Cited 10 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effects of elevated-temperature ion bombardment of wurtzite GaN films preamorphized by ion implantation are studied by Rutherford backscattering/channeling spectrometry and transmission electron microscopy. Amorphous layers annealed in vacuum at 500 °C exhibit polycrystallization. Bombardment of amorphous layers with 2 MeV 63Cu+ ions at elevated temperatures leads to anomalous erosion of GaN (with a sputtering yield of ∼102 at 500 °C), rather than to ion-beam-induced epitaxial crystallization. Temperature dependence of the erosion rate suggests that such a large sputtering yield results from a two-step process of (i) thermally- and ion- beam-induced material decomposition and (ii) ion beam erosion of a highly N-deficient near-surface layer of GaN. This study shows that amorphization during ion implantation should be avoided due to the present inability to epitaxially recrystallize amorphous layers in GaN. © 2000 American Institute of Physics.
Show PACS
61.43.Dq Amorphous semiconductors, metals, and alloys
61.82.Fk Semiconductors
81.05.Ea III-V semiconductors
61.80.Jh Ion radiation effects
61.85.+p Channeling phenomena (blocking, energy loss, etc.)
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Hugoniot data for iron

J. M. Brown, J. N. Fritz, and R. S. Hixson

J. Appl. Phys. 88, 5496 (2000); http://dx.doi.org/10.1063/1.1319320 (3 pages) | Cited 28 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A definitive set of the Los Alamos Hugoniot data for iron in a pressure regime extending to 442 GPa is given. Earlier standards data, obtained using conventional explosive systems, were thoroughly reprocessed. All original film records were reread. On the basis of more recent experiment and theory, some data were culled because the experimental designs were found to be insufficiently conservative. The analysis was also modified to take into account preheating of the explosively driven flyer plates. Minor clerical errors in transcription of measurements were corrected. An improved algorithm for the flash-gap time correction was incorporated. Higher-pressure data were obtained using a conventional 13-pin target assembly on a two-stage light gas gun. Several polynomial representations of the data are given. A linear fit to the data (Us=3.935+1.578 Up, where the shock velocity Us and the particle velocity Up are in km/s) has a root-mean-square misfit of 62 m/s. The quadratic fit (Us=3.691+1.788 Up−0.038 Up2) has a root-mean-square misfit of 39 m/s. © 2000 American Institute of Physics.
Show PACS
62.50.-p High-pressure effects in solids and liquids
64.30.-t Equations of state of specific substances
FREE

Comment on “The multilayer-modified Stoney’s formula for laminated polymer composites on a silicon substrate” [J. Appl. Phys. 86, 5474 (1999)]

Claude A. Klein

J. Appl. Phys. 88, 5499 (2000); http://dx.doi.org/10.1063/1.1318363 (2 pages) | Cited 3 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
There is a vast amount of literature dealing with the strains, the stresses, and the curvature induced by thermal cycling of multilayered laminates, but much of the published work fails to provide proper derivations of the applicable formulas. For example, Kim et al. recently proposed [J. Appl. Phys. 86, 5474 (1999)] a formula — the multilayer-modified Stoney’s formula — for estimating the bow of structures consisting of thin films mounted on a thick substrate, which they validate on the basis of experimental data. In this communication, it is shown that the formula can be derived from available closed-form solutions for the curvature of elastically isotropic multilayer laminates and has no conceptual connection with Stoney’s formula. © 2000 American Institute of Physics.
Show PACS
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.60.Dv Thermal stability; thermal effects
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close