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15 Nov 2004

Volume 85, Issue 20, pp. 4561-4807

Issue Cover Spotlight Figure

Appl. Phys. Lett. 85, 4768 (2004); http://dx.doi.org/10.1063/1.1818331 (3 pages)

G. Walter, N. Holonyak, M. Feng, and R. Chan
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Growth of highly (100) oriented lead zirconate titanate films on silicon and glass substrates using lanthanum nitrate as a buffer layer

Jong-Jin Choi, Chee-Sung Park, Gun-Tae Park, and Hyoun-Ee Kim

Appl. Phys. Lett. 85, 4621 (2004); http://dx.doi.org/10.1063/1.1819519 (3 pages) | Cited 7 times

Online Publication Date: 16 November 2004

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Highly oriented lead zirconate titanate [Pb(Zr,Ti)O3; PZT] thin films were deposited on Pt∕Ti∕SiO2∕Si and glass substrates by the sol-gel method using lanthanum nitrate as a buffer layer. When the lanthanum nitrate buffer layer was annealed at temperatures between 450 and 550 °C, the PZT layer coated onto this buffer layer showed strong (100) orientation. The film deposited on the buffer layer had this orientation, regardless of the other deposition conditions, such as the pyrolysis temperature, pyrolysis time, annealing temperature, and heating rate. The lanthanum nitrate buffer layer also acted as a very effective diffusion barrier against Pb–Si interdiffusion, thus allowing for the direct deposition of PZT films on Si, SiO2∕Si, and glass substrates. Using this buffer layer, highly oriented PZT film was fabricated stably and reproducibly, regardless of substrate material and the coating conditions. The nature of the lanthanum nitrate buffer layer and its role in the growth of the highly (100) oriented PZT films were investigated.
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77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
68.55.A- Nucleation and growth
68.55.-a Thin film structure and morphology
81.40.Gh Other heat and thermomechanical treatments
66.30.Ny Chemical interdiffusion; diffusion barriers
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
68.35.B- Structure of clean surfaces (and surface reconstruction)

Microscopic study on the behavior of the {311} facet in the selective epitaxial growth of Si(100)

Gun-Do Lee, Seung-Hyun Lim, and Euijoon Yoon

Appl. Phys. Lett. 85, 4624 (2004); http://dx.doi.org/10.1063/1.1818730 (3 pages) | Cited 1 time

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The behavior of the {311} facet, which is observed in the selective epitaxial growth of Si(100), is investigated by ab initio calculations and by tight-binding calculations using the environment-dependent tight-binding Si potential. The most stable structure of the {311} facet in the long range order is found to be 3×2 interstitial structure based on the calculation of the surface energy. By comparing the maximum binding energies of adatoms on various structures of Si(311), it is found that the phase transition observed at ∼700 °C is the transition from the 3×2 interstitial to the 3×1 interstitial structure and the phase transition is responsible for the behavior of the {311} facet. By tight-binding molecular dynamics simulation, it is also confirmed that the transition from the 3×2 interstitial to the 3×1 interstitial structure is induced by an adatom at high temperature and it corresponds to the transition from the 3×2 to the 3×1 phase of the Si(311) surface observed in experiment.

High-resolution transmission electron microscopy analysis of the interface between a Tl-1223 (001) superconducting film and an untextured Ag substrate

Bong-Jun Kim, Yoshio Matsui, Shigeo Horiuchi, Dae-Yeong Jeong, Christian Deinhofer, and Gerhard Gritzner

Appl. Phys. Lett. 85, 4627 (2004); http://dx.doi.org/10.1063/1.1814804 (3 pages) | Cited 6 times

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The interface between a screen-printed (Tl0.5Pb0.5)(Sr0.85Ba0.15)2Ca2Cu3Oy (Tl-1223) superconducting film and an untextured Ag substrate is analyzed by transmission electron microscopy (TEM). Preferential orientation between the Tl-1223 grains and the Ag substrate is found. The (001) plane of Tl-1223 grains is parallel to and the {113} plane of Ag is almost parallel to the interface. High-resolution TEM images show that CuO2 planes contact the faceted {113} planes of Ag substrate at the interface. A mechanism for the preferential growth of the Tl-1223 (001) film on untextured Ag substrate is proposed.

Growth of thick (11math0) GaN using a metal interlayer

P. R. Tavernier, B. Imer, S. P. DenBaars, and D. R. Clarke

Appl. Phys. Lett. 85, 4630 (2004); http://dx.doi.org/10.1063/1.1818736 (3 pages) | Cited 8 times

Online Publication Date: 16 November 2004

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Thick films of (11math0)-oriented GaN have been grown on Ti-coated metal organic chemical vapor deposition templates using hydride vapor phase epitaxy. Significant reductions in crack density were observed enabling 240 μm thick films to be grown on sapphire. The use of Ti interlayers was shown to generate significant fractions of voids at the interlayer regrowth interface facilitating void-assisted separation on cooling. Ti metal layers annealed under optimal conditions were found to produce a TiN nanomask suitable for lateral overgrowth during HVPE. An estimate of the void size required to allow spontaneous delamination of the substrate at the TiN–GaN interface is discussed with reference to growth conditions.
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81.05.Ea III-V semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.55.A- Nucleation and growth
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.-a Thin film structure and morphology
68.60.Bs Mechanical and acoustical properties
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.M- Structural failure of materials
61.72.Qq Microscopic defects (voids, inclusions, etc.)
81.40.Gh Other heat and thermomechanical treatments

Electrical and optical properties of rod-like defects in silicon

J. P. Goss, P. R. Briddon, T. A. G. Eberlein, R. Jones, N. Pinho, A. T. Blumenau, and S. Öberg

Appl. Phys. Lett. 85, 4633 (2004); http://dx.doi.org/10.1063/1.1814425 (3 pages) | Cited 7 times

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Self-interstitials in silicon can aggregate to form rod-like defects (RLDs) having both electrical and optical activity. We carry out local density functional calculations for both {113} and {111} RLDs to determine their structures and electrical activity. We find that small {113} RLDs are more stable than {111} RLDs but this reverses for larger defects. We attribute the electrical activity of {113} RLDs found in deep level transient spectroscopy studies with the bounding dislocations and the 0.903 eV photoluminescence to vacancy point defects lying on the habit plane.

Clamping effects in the Al2O3(11math0)∕Nb(110)∕Eu(110) epitaxial system

S. Soriano, C. Dufour, K. Dumesnil, J. A. Borchers, and Ph. Mangin

Appl. Phys. Lett. 85, 4636 (2004); http://dx.doi.org/10.1063/1.1821658 (3 pages) | Cited 5 times

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In-plane and out-of-plane lattice parameters of Nb and Eu have been measured as a function of temperature between 10 and 300 K in the Al2O3(11math0)∕Nb(110)∕Eu(110) epitaxial system. It is shown that the Nb lattice is clamped in the growth plane to the sapphire substrate, in the whole temperature range. On its own, the Eu lattice is totally free to expand isotropically above a clamping temperature Tcl, below which in-plane parameters also freeze to an almost constant value. This well-defined clamping temperature strongly depends on the Eu thickness and likely is related to the thermal mobility of interface defects.

Electromigration lifetime and critical void volume

Jun He, Z. Suo, T. N. Marieb, and J. A. Maiz

Appl. Phys. Lett. 85, 4639 (2004); http://dx.doi.org/10.1063/1.1821631 (3 pages) | Cited 10 times

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We study electromigration in copper lines encapsulated in an organosilicate glass. A line fails when a void near the upstream via grows to a critical volume. We calculate the void volume as a function of time. The statistical distribution of the critical volume (DCV) is taken to be independent of testing variables, such as line length and electric current density. By contrast, the distribution of the lifetime (DLT) strongly depends on these testing variables. We deduce the DCV from the experimentally measured DLT. Once deduced, the DCV can predict the DLT under untested conditions.

Spatially resolved measurements of thermal parameters in colloidal suspensions in liquid crystals

F. Mercuri, U. Zammit, and M. Marinelli

Appl. Phys. Lett. 85, 4642 (2004); http://dx.doi.org/10.1063/1.1821655 (3 pages) | Cited 4 times

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We report on spatially resolved measurements with a spatial resolution of about 0.1 mm of the transition temperature and of the behavior of the heat capacity, thermal conductivity, and thermal diffusivity over the smectic A–nematic and nematic–isotropic phase transitions in an inhomogeneous aerosil dispersed 8CB liquid crystal. The results were obtained by means of a recently implemented photopyroelectric setup which combines the capability for high temperature resolution measurements with the possibility of visual access in the sample. It is shown that the results relative to different local concentration of particles are consistent with the ones obtained previously on homogeneous samples with different average particle concentration. Finally, the analysis of the local thermal conductivity values has led to an approximate estimate of the local particle concentration in the sample.

Femtosecond real-time pump–probe imaging spectroscopy

Naoki Furukawa, Chad E. Mair, Valeria D. Kleiman, and Jun Takeda

Appl. Phys. Lett. 85, 4645 (2004); http://dx.doi.org/10.1063/1.1823039 (3 pages) | Cited 6 times

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Real-time pump–probe imaging spectroscopy with femtosecond time resolution is demonstrated. This method allows real-time mapping of frequency- and time-resolved transient absorption of materials at once. We can clearly measure the image of the transient absorption spectra of β-carotene with wide temporal and spectral ranges in a short accumulation time. Since the typical accumulation time is about two orders of magnitude shorter than that by the conventional pump–probe technique, this method becomes a powerful spectroscopic tool to study ultrafast relaxation and dynamics on organic/biochemical materials, which easily undergo photofatigue after many repetitions of the pump–probe sequence.

Bending of dislocations in GaN during epitaxial lateral overgrowth

S. Gradečak, P. Stadelmann, V. Wagner, and M. Ilegems

Appl. Phys. Lett. 85, 4648 (2004); http://dx.doi.org/10.1063/1.1823593 (3 pages) | Cited 20 times

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Bending of dislocations in GaN during epitaxial lateral overgrowth (ELO) has been experimentally studied using transmission electron microscopy. The orientational dependence of the dislocation energy factor K has been calculated on the basis of anisotropic elasticity theory for different types of perfect dislocation in GaN. Image forces act on dislocations during the growth and dislocations bend to achieve the minimum energy. Bending behavior depends on a dislocation type and we show that the measured bending angles correspond to the calculated energy minima. The results allow us to quantitatively discuss the most advantageous ELO GaN mask direction for the largest dislocation density reduction.

Effect of layer thickness on the electrostatic potential in InGaN quantum wells

M. Stevens, A. Bell, M. R. McCartney, F. A. Ponce, H. Marui, and S. Tanaka

Appl. Phys. Lett. 85, 4651 (2004); http://dx.doi.org/10.1063/1.1815376 (3 pages) | Cited 14 times

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High-resolution electron holography in the transmission electron microscope has the capability to profile the spatial variation of the electrostatic potential in semiconductors, at subnanometer resolution. We have used electron holography to measure the internal electrostatic potential and fields across quantum wells with well thickness ranging from 2 to 10 nm, at a nominal indium concentration of x=0.13. A comparison of field strength versus well width shows a precipitous drop in field strength beyond 6 nm. A close look at the microstructure of the widest well shows additional contrast at the growth interface. An explanation consistent with both observations supports the possibility of compositional fluctuations in combination with strain relaxation at the early stages of growth of the quantum well.

In situ neutron diffraction studies on the elevated-temperature deformation behavior of a TiAl–W alloy

Hahn Choo, Dongyi Seo, Jonathan Beddoes, Mark A. M. Bourke, and Donald W. Brown

Appl. Phys. Lett. 85, 4654 (2004); http://dx.doi.org/10.1063/1.1823043 (3 pages) | Cited 8 times

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The evolution of elastic lattice strain in a Ti–48Al–2W (at.%) alloy, subjected to (1) quasistatic tensile loading and (2) constant-load tensile creep, was investigated at 1033 K using in situ neutron diffraction. During the quasistatic test to a maximum stress of 435 MPa, a- and c-axes lattice strains increased linearly with a small degree of anisotropy (matha∕mathc≅0.9) up to 200 MPa, followed by a significant redistribution of load above 260 MPa due to the plastic anisotropy. Time-resolved in situ measurements were also performed during the creep at 276 and 327 MPa. The results show that lattice strain evolution during the primary creep is qualitatively similar to the quasistatic case under the current test conditions.

Energy band dispersion in well ordered N,N′-dimethyl-3,4,9,10-perylenetetracarboxylic diimide films

G. N. Gavrila, H. Mendez, T. U. Kampen, D. R. T. Zahn, D. V. Vyalikh, and W. Braun

Appl. Phys. Lett. 85, 4657 (2004); http://dx.doi.org/10.1063/1.1800273 (3 pages) | Cited 22 times

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The electronic properties of well ordered N,N′-dimethyl-3,4,9,10-perylenetetracarboxylic dimide (DiMe-PTCDI) films prepared on sulfur passivated GaAs(001) substrates were studied by means of photoemission spectroscopy. From the photon energy dependence of normal emission spectra an intermolecular energy band dispersion of about 0.2 eV was determined for the highest occupied molecular orbital (HOMO). Simulation of the density of states reveals that the HOMO band has a single π -character. The observed energy band dispersion thus originates from the intermolecular π-π interaction and is modeled using the tight binding model. The analysis provides a value of 0.04 eV for the transfer integral. The inner potential was treated as a fitting parameter such that the expected periodicity of the dispersion in the reciprocal space was obtained.
Show PACS
71.20.Nr Semiconductor compounds
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)
79.60.Bm Clean metal, semiconductor, and insulator surfaces
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