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15 Jul 2002

Volume 81, Issue 3, pp. 391-566

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Anelastic deformation of Pb(Zr,Ti)O3 thin films by non-180° ferroelectric domain wall movements during nanoindentation

M. Algueró, A. J. Bushby, M. J. Reece, and A. Seifert

Appl. Phys. Lett. 81, 421 (2002); http://dx.doi.org/10.1063/1.1491291 (3 pages) | Cited 6 times

Online Publication Date: 2 July 2002

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Lead zirconate titanate Pb(Zr,Ti)O3 ferroelectric thin films show significant anelastic deformation when indented with spherical tipped indenters. Experiments on films with different Zr/Ti ratio and a mixed 〈001〉,〈100〉 preferred crystallographic orientation have shown that there is a good agreement between the anelastic deformation and the maximum strain achievable by non-180° domain wall movement. An expected increase of the indentation stiffness of the films also accompanies the anelastic deformation because of the single crystal elastic anisotropy. All these observations seem to indicate that non-180° ferroelectric domain wall movements occur under indentation stresses and cause anelasticity. Stresses for maximum anelastic deformation are compared with those for recently reported stress-induced depolarization. © 2002 American Institute of Physics.
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62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
68.60.Bs Mechanical and acoustical properties
77.80.Dj Domain structure; hysteresis
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
62.20.M- Structural failure of materials
62.20.Qp Friction, tribology, and hardness
68.35.Gy Mechanical properties; surface strains
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep
68.55.-a Thin film structure and morphology
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
62.20.D- Elasticity

Low-threshold blue amplified spontaneous emission in a statistical copolymer and its blend

Tae-Woo Lee, O Ok Park, Dong Hoon Choi, Hyun Nam Cho, and Young Chul Kim

Appl. Phys. Lett. 81, 424 (2002); http://dx.doi.org/10.1063/1.1491297 (3 pages) | Cited 10 times

Online Publication Date: 2 July 2002

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We report low-threshold, blue amplified spontaneous emission (ASE) in a statistical copolymer, poly(9,9-dihexylfluorene-2,7-divinylene-m-phenylenevinylene-stat-p-phenylenevinylene) (CPDHFPV) and its blend with poly(9-vinylcarbazole) (PVK). PVK and CPDHFPV acted as the donor and the acceptor of the Förster-type excitation energy transfer, respectively. A single component waveguide made of CPDHFPV gave the threshold energy of 160 nJ/cm2/pulse. Moreover, that of the PVK/CPDHFPV (95/5 by wt.) blend device was as low as 20 nJ/cm2/pulse. From the relationship between the ASE intensity and the film thickness, we suggest that the optimum thickness for the photopumped ASE should be the transverse electric-mode cutoff thickness. © 2002 American Institute of Physics.
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78.45.+h Stimulated emission
42.70.Jk Polymers and organics

Effect of electrical boundary conditions on ferroelectric domain structures in thin films

Y. L. Li, S. Y. Hu, Z. K. Liu, and L. Q. Chen

Appl. Phys. Lett. 81, 427 (2002); http://dx.doi.org/10.1063/1.1492025 (3 pages) | Cited 50 times

Online Publication Date: 2 July 2002

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The domain structures in a ferroelectric thin film are studied using a phase-field model. A cubic-to-tetragonal ferroelectric phase transition in lead titanate thin film is considered. Both elastic interactions and electrostatic interactions are taken into account. The focus is on the effect of electrical boundary conditions on the domain morphologies and volume fractions. It is shown that different electric boundary conditions may have a significant effect on the domain structures. © 2002 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
77.80.Dj Domain structure; hysteresis
77.80.B- Phase transitions and Curie point
77.22.Ej Polarization and depolarization

Analysis of SiO2/Si(001) interface roughness for thin gate oxides by scanning tunneling microscopy

Masahide Gotoh, Koichi Sudoh, Hiroyasu Itoh, Kazunori Kawamoto, and Hiroshi Iwasaki

Appl. Phys. Lett. 81, 430 (2002); http://dx.doi.org/10.1063/1.1494124 (3 pages) | Cited 4 times

Online Publication Date: 2 July 2002

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We studied the interface roughnesses of SiO2/Si(001) for gate oxides of 8 and 15 nm thicknesses together with RCA-treated samples by using scanning tunneling microscopy (STM). By STM observation and scaling analysis we made clear that the interface roughnesses of thermal oxides/Si substrates were similar to each other and to that of the chemical oxide/Si substrate prior to thermal oxidation; the correlation length was 23–26 nm and the rms roughness at length scales larger than the correlation length was 0.28–0.29 nm. The results indicate that the interface roughnesses of the oxides are determined by the processes prior to the oxidations. © 2002 American Institute of Physics.
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81.65.Mq Oxidation
81.05.Cy Elemental semiconductors
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.35.Ct Interface structure and roughness
68.35.B- Structure of clean surfaces (and surface reconstruction)

Growth of single-wall carbon nanotubes within an ordered array of nanosize silica spheres

A. Lan, Z. Iqbal, A. Aitouchen, M. Libera, and H. Grebel

Appl. Phys. Lett. 81, 433 (2002); http://dx.doi.org/10.1063/1.1492846 (3 pages) | Cited 14 times

Online Publication Date: 2 July 2002

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Single-wall carbon nanotubes (SWCNTs), which were well-separated individuals or, small bundles of two to five tubes, were produced in a controllable manner by disproportionation of CO at 700 °C and 1 atm in the voids of an ordered array of silica spheres with embedded bimetallic Mo/Co catalytic particles. A combination of transmission electron microscopy, electron energy-loss spectroscopy, and Raman scattering excited with an Ar laser at λ = 514.5 nm (2.41 eV), was used to characterize the nanotubes. The corresponding Raman spectra strongly indicate that these nanotubes are primarily chiral. This method offers a valid route for a high-quality single-step production of SWCNT composites for mechanical, electronic, and optoelectronic applications. © 2002 American Institute of Physics.
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81.07.De Nanotubes
61.46.-w Structure of nanoscale materials
78.67.Ch Nanotubes
78.30.Na Fullerenes and related materials
81.16.Hc Catalytic methods
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
68.37.Lp Transmission electron microscopy (TEM)
79.20.Uv Electron energy loss spectroscopy
42.70.Mp Nonlinear optical crystals

Studies of phase segregation in Cd1−xZnxTe using surface photovoltage spectroscopy

Y. Zidon, Jihua Yang, and Yoram Shapira

Appl. Phys. Lett. 81, 436 (2002); http://dx.doi.org/10.1063/1.1493230 (3 pages) | Cited 6 times

Online Publication Date: 2 July 2002

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Cd1−xZnxTe wafers used for x-ray detector arrays have been failure analyzed using x-ray diffraction, x-ray electron spectroscopy (XPS), energy dispersive spectroscopy (EDS), and surface photovoltage spectroscopy (SPS). The last shows ZnTe segregation in failed pixels while the precipitant phase is too small to be observed by the other techniques. The Zn concentration, measured using EDS and XPS, was higher than that deduced from SPS data, confirming the conclusion. The segregation can be revealed only by SPS since it is sensitive to the electronic structure and thus to x in each phase while the other techniques average x over their measurement volume. © 2002 American Institute of Physics.
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64.75.-g Phase equilibria
73.25.+i Surface conductivity and carrier phenomena
79.60.Bm Clean metal, semiconductor, and insulator surfaces

Growth of Fe doped semi-insulating GaN by metalorganic chemical vapor deposition

Sten Heikman, Stacia Keller, Steven P. DenBaars, and Umesh K. Mishra

Appl. Phys. Lett. 81, 439 (2002); http://dx.doi.org/10.1063/1.1490396 (3 pages) | Cited 89 times

Online Publication Date: 2 July 2002

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Iron doped GaN layers were grown by metalorganic chemical vapor deposition (MOCVD) using ferrocene as the Fe precursor. Specular films with concentrations up to 1.7×1019 cm−3, as determined by secondary ion mass spectrometry, were grown. The Fe concentration in the film showed a linear dependence on the precursor partial pressure, and was insensitive to growth temperature, pressure, and ammonia partial pressure. Memory effects were observed, similar to Mg doping of GaN by MOCVD. The deep acceptor nature of Fe was used for growth of semi-insulating GaN films on sapphire substrates. A 2.6-μm-thick GaN film with a resistivity of 7×109 Ω/sq was attained when the first 0.3 μm of the film was Fe doped. X-ray diffraction rocking curves indicated high crystalline quality, very similar to an undoped film, showing that Fe doping did not affect the structural properties of the film. Fe doping allows for growth of semi-insulating GaN on sapphire without the high threading dislocation densities and/or high carbon levels that are normally necessary to achieve insulating films. © 2002 American Institute of Physics.
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68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
61.72.S- Impurities in crystals
61.72.up Other materials
73.61.Ey III-V semiconductors
71.55.Eq III-V semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Nephelauxetic effect in LiNbO3:Cr3+ crystals

S. W. Biernacki, A. Kamińska, A. Suchocki, and L. Arizmendi

Appl. Phys. Lett. 81, 442 (2002); http://dx.doi.org/10.1063/1.1493225 (3 pages) | Cited 10 times

Online Publication Date: 2 July 2002

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A model, based on the Harrison theory of bonding is developed for quantitative explanation of the nephelauxetic effect, i.e., a reduction of interelectronic crystal field Racah repulsion parameters B and C due to the covalency of bonds. The results are used for a description of the effect in chromium-doped lithium niobate crystals. The model can be also applied to other systems. © 2002 American Institute of Physics.
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71.70.Ch Crystal and ligand fields
61.50.Lt Crystal binding; cohesive energy

Controlled ice nucleation in microsized water droplet

Du Ning and X. Y. Liu

Appl. Phys. Lett. 81, 445 (2002); http://dx.doi.org/10.1063/1.1492849 (3 pages) | Cited 8 times

Online Publication Date: 2 July 2002

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Controlled ice nucleation in a microsized water droplet was examined using a microdroplet suspension method. This method allows us to minimize the effect of the container wall and foreign particles. The influence of the water droplet volume on microdrop nucleation is examined quantitatively. It is found that at the microscale, the volume effect exerts a large influence on nucleation kinetics. This technique enabled us to quantify the effect of lysozyme on ice nucleation kinetics. It turns out that lysozyme promotes ice nucleation at relatively high supercoolings by decreasing the interfacial free energy between the nucleating phase and foreign particles. This quantitative measurement of the interfacial effect of additives (impurities) on ice nucleation kinetics will exert a significant impact on the research on the mechanism of antifreeze and nucleation promotion. © 2002 American Institute of Physics.
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64.70.D- Solid-liquid transitions
82.70.Kj Emulsions and suspensions
68.08.-p Liquid-solid interfaces

Anomalous x-ray diffraction on InAs/GaAs quantum dot systems

T. U. Schülli, M. Sztucki, V. Chamard, T. H. Metzger, and D. Schuh

Appl. Phys. Lett. 81, 448 (2002); http://dx.doi.org/10.1063/1.1491293 (3 pages) | Cited 12 times

Online Publication Date: 2 July 2002

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Free-standing InAs quantum dots on a GaAs (001) substrate have been investigated using grazing incidence x-ray diffraction. To suppress the strong scattering contribution from the GaAs substrate, we performed anomalous diffraction experiments at the superstructure (200) reflection, showing that the relative intensities from the dots and the substrate undergo a significant change with the x-ray energy below and above the As K edge. Since the signal from the substrate material can essentially be suppressed, this method is ideally suited for the investigation of strain, shape, and interdiffusion of buried quantum dots and quantum dots embedded in heteroepitaxial multilayers. In addition, we show that it can be used as a tool for studying wetting layers. © 2002 American Institute of Physics.
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68.65.Hb Quantum dots (patterned in quantum wells)
61.05.cm X-ray reflectometry (surfaces, interfaces, films)

Thermistor ceramic with negative temperature coefficient based on Zn7Sb2O12: An inverse spinel-type phase

M. A. L. Nobre and S. Lanfredi

Appl. Phys. Lett. 81, 451 (2002); http://dx.doi.org/10.1063/1.1494101 (3 pages) | Cited 17 times

Online Publication Date: 2 July 2002

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The electric properties of the semiconductor ceramic Zn7Sb2O12 were investigated by impedance spectroscopy. The grain resistance exhibits a thermistor behavior with negative temperature coefficient. Two regions on the resistance curve were identified. Each region shows a different thermistor characteristic parameter (β), which is equal to 3170 and 3845 °C, at measurement temperatures up to 350 °C and above 450 °C, respectively. The temperature coefficient of the resistance (α) was derived being equal to −2.59×10−2 °C−1 and −1.89×10−2 °C−1, at 350 and 450 °C, respectively. The anomalous behavior of the resistance is further evidence of phase transition phenomenon. © 2002 American Institute of Physics.
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72.20.Fr Low-field transport and mobility; piezoresistance
72.80.Jc Other crystalline inorganic semiconductors
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
84.32.Ff Conductors, resistors (including thermistors, varistors, and photoresistors)

Band gap narrowing of titanium dioxide by sulfur doping

T. Umebayashi, T. Yamaki, H. Itoh, and K. Asai

Appl. Phys. Lett. 81, 454 (2002); http://dx.doi.org/10.1063/1.1493647 (3 pages) | Cited 424 times

Online Publication Date: 2 July 2002

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Titanium dioxide (TiO2) doped with sulfur (S) was synthesized by oxidation annealing of titanium disulfide (TiS2). According to the x-ray diffraction patterns, TiS2 turned into anatase TiO2 when annealed at 600 °C. The residual S atoms occupied O-atom sites in TiO2 to form Ti�S bonds. The S doping caused the absorption edge of TiO2 to be shifted into the lower-energy region. Based on the theoretical analyses using ab initio band calculations, mixing of the S 3p states with the valence band was found to contribute to the band gap narrowing. © 2002 American Institute of Physics.
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71.20.Ps Other inorganic compounds
81.65.Mq Oxidation
81.40.Gh Other heat and thermomechanical treatments
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
71.15.-m Methods of electronic structure calculations

Intense visible light emission from stress-activated ZrO2:Ti

Morito Akiyama, Chao-Nan Xu, and Kazuhiro Nonaka

Appl. Phys. Lett. 81, 457 (2002); http://dx.doi.org/10.1063/1.1494463 (3 pages) | Cited 16 times

Online Publication Date: 2 July 2002

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We have investigated the luminescence phenomena from stress-activated ZrO2:Ti. The luminescence is clearly visible to the naked eye in the atmosphere. The luminescence center has been identified as the Ti4+ ion from spectra of the mechanoluminescence and also from photoluminescence studies of ZrO2:Ti. The mechanoluminescence intensity decreases on repetitive application of stress but recovers completely on irradiation with ultraviolet light. ZrO2 is an n-type semiconductor and has electron traps. It is suggested that the mechanoluminescence mechanism arises from the movement of dislocations and recombination between electrons and holes released from these traps which are associated with the Ti4+ centers. © 2002 American Institute of Physics.
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78.60.Mq Sonoluminescence, triboluminescence
71.55.Ht Other nonmetals
61.82.Fk Semiconductors
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
78.55.Hx Other solid inorganic materials
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Laser-like mechanoluminescence in ZnMnTe-diluted magnetic semiconductor

D. Raja Reddy and B. K. Reddy

Appl. Phys. Lett. 81, 460 (2002); http://dx.doi.org/10.1063/1.1494116 (3 pages) | Cited 9 times

Online Publication Date: 2 July 2002

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Laser-like mechanoluminescence is reported in the spintronic material ZnMnTe. The luminescence was also observed when the material was exposed to UV and x-rays. Photoluminescence spectra consisted of peaks at 386.5 and 648 nm, which may be attributed to band gap, and Mn2+ levels, respectively. Lattice contraction, sharpness of the x-ray diffraction peak, and the blueshift in the energy gap confirm the nanostructure of the material. A possible mechanism for lasing is also suggested. © 2002 American Institute of Physics.
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75.50.Pp Magnetic semiconductors
78.60.Mq Sonoluminescence, triboluminescence
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.55.Et II-VI semiconductors
61.46.-w Structure of nanoscale materials

The anomalous bandgap bowing in GaAsN

U. Tisch, E. Finkman, and J. Salzman

Appl. Phys. Lett. 81, 463 (2002); http://dx.doi.org/10.1063/1.1494469 (3 pages) | Cited 52 times

Online Publication Date: 2 July 2002

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The composition dependence of the fundamental bandgap of thin, pseudomorphic GaAs1−xNx layers (0 ⩽ x ⩽ 5%) on GaAs substrates is studied by optical transmission measurements and high resolution x-ray diffraction. We present a very large set of consistent experimental data. An empirical double exponential composition dependence of the bowing parameter is obtained. This expression accurately describes the measured bandgaps, and allows estimations for higher N incorporations. The bowing parameter reaches 40 eV for very low N incorporations (x ≈ 0.1%), and strongly decreases with increasing N molar fraction. We estimate that the bowing parameter would reach a constant value of 7.5 eV for x≳8%, as in an alloy. This bowing would not be sufficient to close the bandgap for higher N incorporations. © 2002 American Institute of Physics.
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71.20.Nr Semiconductor compounds
78.66.Fd III-V semiconductors
68.55.Nq Composition and phase identification
78.40.Fy Semiconductors

Optical performance of nanocrystalline transparent ceria films

P. Patsalas, S. Logothetidis, and C. Metaxa

Appl. Phys. Lett. 81, 466 (2002); http://dx.doi.org/10.1063/1.1494458 (3 pages) | Cited 40 times

Online Publication Date: 2 July 2002

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Ceria is a transparent oxide suitable for various optical and optoelectronic devices. In this work, we tailor independently the refractive index n and fundamental gap Eg of nanocrystalline Ceria films by varying the substrate temperature or using Ar+ ion beams during growth with electron beam evaporation. Spectroscopic ellipsometry and x-ray reflectivity are employed to study n and Eg and to identify the physical parameters that affect them. We correlate n (varies from 1.65 to 2.15 in the studied films) with the film density through a universal, square law. The film composition strongly affects Eg, which varies from 2.8 to ∼2.0 eV. The optical absorption below 3 eV and the Eg shift are attributed to O-defect states and not to modifications in interband transitions. © 2002 American Institute of Physics.
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77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
78.66.Nk Insulators
77.55.-g Dielectric thin films
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.Nq Composition and phase identification
71.55.Ht Other nonmetals

Structural characterization of nonpolar (11math0) a-plane GaN thin films grown on (1math02) r-plane sapphire

M. D. Craven, S. H. Lim, F. Wu, J. S. Speck, and S. P. DenBaars

Appl. Phys. Lett. 81, 469 (2002); http://dx.doi.org/10.1063/1.1493220 (3 pages) | Cited 222 times

Online Publication Date: 2 July 2002

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In this letter we describe the structural characteristics of nonpolar (11math0) a-plane GaN thin films grown on (1math02) r-plane sapphire substrates via metalorganic chemical vapor deposition. Planar growth surfaces have been achieved and the potential for device-quality layers realized by depositing a low temperature nucleation layer prior to high temperature epitaxial growth. The in-plane orientation of the GaN with respect to the r-plane sapphire substrate was confirmed to be [0001]GaN‖[math101]sapphire and [math100]GaN‖[11math0]sapphire. This relationship is explicitly defined since the polarity of the a-GaN films was determined using convergent beam electron diffraction. Threading dislocations and stacking faults, observed in plan-view and cross-sectional transmission electron microscope images, dominated the a-GaN microstructure with densities of 2.6×1010 cm−2 and 3.8×105 cm−1, respectively. Submicron pits and crystallographic terraces were observed on the optically specular a-GaN surface with atomic force microscopy. © 2002 American Institute of Physics.
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68.55.-a Thin film structure and morphology
68.55.A- Nucleation and growth
81.05.Ea III-V semiconductors
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
68.37.Lp Transmission electron microscopy (TEM)
61.72.Nn Stacking faults and other planar or extended defects
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase
61.72.Lk Linear defects: dislocations, disclinations
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Ps Atomic force microscopy (AFM)

Thermal stability and structural characteristics of HfO2 films on Si (100) grown by atomic-layer deposition

M.-H. Cho, Y. S. Roh, C. N. Whang, K. Jeong, S. W. Nahm, D.-H. Ko, J. H. Lee, N. I. Lee, and K. Fujihara

Appl. Phys. Lett. 81, 472 (2002); http://dx.doi.org/10.1063/1.1487923 (3 pages) | Cited 164 times

Online Publication Date: 2 July 2002

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The thermal stability and structural characteristics for gate stack structure of HfO2 dielectrics deposited by atomic-layer deposition (ALD) were investigated. The structural characteristics and chemical state of the HfO2 films in relation to the film thickness and postannealing temperature were examined by x-ray diffraction and x-ray photoelectron spectroscopy. An interfacial layer of hafnium silicate with an amorphous structure was grown on the oxidized Si substrate at an initial growth stage. The structural characteristics of the HfO2 films are closely affected by the interfacial layer and are depended on the thickness of the films. The 45 Å thick HfO2 film with an amorphous structure was changed into a polycrystalline structure after rapid temperature annealing of 750 °C for 5 min, while thicker films were grown into a polycrystalline structure of monoclinic or tetragonal crystal structure. The silicate layer grown at the interfacial region is not stable even at 700 °C under ultrahigh vacuum condition and changes into the silicide layers. © 2002 American Institute of Physics.
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68.60.Dv Thermal stability; thermal effects
77.55.-g Dielectric thin films
68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
61.72.Cc Kinetics of defect formation and annealing
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
68.49.Uv X-ray standing waves
68.37.Xy Scanning Auger microscopy, photoelectron microscopy
79.60.-i Photoemission and photoelectron spectra

Synchrotron x-ray scattering study on the evolution of surface morphology of the InN/Al2O3(0001) system

Ik Jae Lee, Jin Woo Kim, Tae-Bong Hur, Yoon-Hwae Hwang, and Hyung-Kook Kim

Appl. Phys. Lett. 81, 475 (2002); http://dx.doi.org/10.1063/1.1489082 (3 pages) | Cited 9 times

Online Publication Date: 2 July 2002

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Dynamic scaling behavior was studied for InN films grown on sapphire(0001) substrates using high-resolution synchrotron x-ray reflectivity and atomic force microscopy measurements. In the early stage of growth, highly strained planar InN films were grown. As the film thickness approaches an effective critical thickness, the growth gradually crosses over to the island growth. Concurrently, the relaxation of the lattice strain begins and the growth front becomes rougher. The roughness increases mostly during the intermediate crossover regime where the strain is relieved. In this regime, the dynamic scaling exponent, β, is estimated as 1.754±0.071. The evolution of the surface roughness in the final-stage growth can be described by the dynamic scaling exponent of 0.236±0.022. © 2002 American Institute of Physics.
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68.35.B- Structure of clean surfaces (and surface reconstruction)
68.55.-a Thin film structure and morphology
68.37.Ps Atomic force microscopy (AFM)
78.70.Ck X-ray scattering
81.05.Ea III-V semiconductors
68.49.Uv X-ray standing waves
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