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15 Mar 1999

Volume 85, Issue 6, pp. 3019-3386

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Structural changes induced by nitrogen in the a-Ge:H network

R. R. Campomanes, D. Comedi, and I. Chambouleyron

J. Appl. Phys. 85, 3108 (1999); http://dx.doi.org/10.1063/1.369847 (6 pages)

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The structural modifications induced by the incorporation of nitrogen (2 at.%<CN<6 at. %, CN = N concentration) in radio frequency-sputtered hydrogenated amorphous germanium (a-Ge:H) has been studied by infrared spectroscopy. At all N concentrations there is a substantial increase of the density of voids, as indicated by the strength of the absorption band associated with the surface-like stretching vibration of the Ge–H dipole. As CN increases, the peak position of this mode shifts to smaller values. These effects are also detected through the analysis of the wagging vibration modes of the Ge–H dipole. Comparison of the present results with similar data for H-free a:GeN indicates that the presence of H in the reaction hinders the incorporation of the NGe3 skeletal group, characteristic of β-Ge3N4. The overall data indicate that almost all N incorporates in N–H and N–H2 configurations, which are responsible for the formation of a large quantity of small-size voids. © 1999 American Institute of Physics.
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61.43.Dq Amorphous semiconductors, metals, and alloys
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Cd Deposition by sputtering
78.66.Jg Amorphous semiconductors; glasses
78.35.+c Brillouin and Rayleigh scattering; other light scattering

Removal of end-of-range defects in Ge+-pre-amorphized Si by carbon ion implantation

Peng-Shiu Chen, T. E. Hsieh, and Chih-Hsun Chu

J. Appl. Phys. 85, 3114 (1999); http://dx.doi.org/10.1063/1.369694 (6 pages) | Cited 3 times

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Carbon ion implantation was employed to annihilate the end-of-range (EOR) defects in Ge+-pre-amorphized Si. Experimental results showed that the efficiency of EOR defect removal depends on the Ge+-pre-amorphization conditions, the location of projected range (Rp) of carbon implant and subsequent annealing conditions. The best defect removal occurred when Rp of carbon implantation was brought close to the amorphous/crystalline (a/c) interface generated by Ge+-pre-amorphization. The higher the annealing temperature, the better the interstitial gettering efficiency of carbon atoms was observed. However, transmission electron microscopy investigation revealed the emergence of hairpin dislocations when dose and accelerating voltage of Ge+ implantation were high. In specimens without carbon implantation, the hairpin dislocations could be readily removed by a 900 °C, 30 min anneal. For carbon-implanted specimens, the density of hairpin dislocations increased when Rp of carbon implantation was close to the (a/c) interface. The glide motion of hairpin dislocations was affected by Ge+-pre-amorphization conditions and was inhibited by the SiC complexes formed in the vicinity of dislocations so that they became rather difficult to anneal out of the specimens. © 1999 American Institute of Physics.
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61.72.uf Ge and Si
61.82.Fk Semiconductors
61.72.Cc Kinetics of defect formation and annealing
61.72.Yx Interaction between different crystal defects; gettering effect
61.80.Jh Ion radiation effects
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Ion-beam induced amorphization and dynamic epitaxial recrystallization in α-quartz

Sankar Dhar, Wolfgang Bolse, and Klaus-Peter Lieb

J. Appl. Phys. 85, 3120 (1999); http://dx.doi.org/10.1063/1.369650 (4 pages) | Cited 12 times

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We report on the evaluation of ion-beam induced damage in α-quartz and its dynamic annealing behavior in the temperature range between 80 and 1050 K using Rutherford backscattering spectrometry in channeling geometry. The results illustrate that the critical temperature for inhibiting amorphization during irradiation is about Tc ≈ 940 K. The critical fluence ϕc for amorphization is independent of the temperature up to 550 K, but strongly increases at higher temperatures. The activation energy for the diffusion of defects in the collision cascade or at the amorphous/crystalline interface is found to be 0.28±0.02 eV. The dynamic annealing mechanism is explained by the vacancy out-diffusion model of Morehead and Crowder. © 1999 American Institute of Physics.
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61.82.Ms Insulators
61.80.Jh Ion radiation effects
66.30.Lw Diffusion of other defects
61.85.+p Channeling phenomena (blocking, energy loss, etc.)
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments
81.10.Jt Growth from solid phases (including multiphase diffusion and recrystallization)
61.43.Er Other amorphous solids
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.

Raman, infrared and x-ray diffraction study of phase stability in La1−xBaxMnO3 doped manganites

Chaitali Roy and R. C. Budhani

J. Appl. Phys. 85, 3124 (1999); http://dx.doi.org/10.1063/1.369651 (8 pages) | Cited 28 times

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Formation of different crystallographic phases and their characteristic Raman and infrared spectra are studied in the manganite system La1−xBaxMnO3 for x in the range of 0 ⩽ x ⩽ 1, and with variations in oxygen stoichiometry. Synthesis of the end member LaMnO3 in pure argon environment leads to the formation of Jahn–Teller distorted, antiferromagnetic orthomanganite. While the observed Raman modes in this compound are primarily due to internal vibrations of MnO6 octahedra, the infrared (IR) spectra show an absorption edge in addition to the IR active phonons. The oxygen rich LaMnO3 is rhombohedral and has fewer zero-wave-vector phonon modes. In the barium substituted compositions with 0<x ⩽ 0.25, a single phase rhombohedral compound of decreasing rhombicity is formed. A further increase in x leads to the ideal cubic perovskite structure for which a factor group analysis yields no Raman active and three IR active phonons of F1u symmetry. The compound with x = 0.35, shows faint Raman modes of hexagonal BaMnO3 (P63mc noncentrosymmetric group) whose presence is not seen in x-ray diffraction data. For x>0.35, all three techniques used here show the formation of a two-phase mixture of La0.65Ba0.35MnO3 and hexagonal BaMnO3. An attempt has been made to correlate the progressive increase in symmetry of the crystal structure, shift of IR absorption edge to lower energies, and disappearance of phonon modes with x and δ with the reported electrical and magnetic behavior of this hole-doped manganite. © 1999 American Institute of Physics.
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61.66.Fn Inorganic compounds
78.30.Hv Other nonmetallic inorganics
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
75.50.Ee Antiferromagnetics
71.28.+d Narrow-band systems; intermediate-valence solids

Effect of preamorphization implantation on C54–TiSi2 formation in salicided narrow lines

Kaori Tai, Masao Okihara, Makiko Kageyama, Yusuke Harada, and Hiroshi Onoda

J. Appl. Phys. 85, 3132 (1999); http://dx.doi.org/10.1063/1.369652 (7 pages) | Cited 2 times

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The effect of the preamorphization implantation (PAI) process on TiSi2 phase transformation has been investigated by using arrays of submicron TiSi2 lines. The C49–C54 transformation of TiSi2 during annealing is promoted by the PAI process. The promotion of phase transformation cannot be explained only by the difference in grain size of the C49–TiSi2; hence, the nucleation site density for the phase transformation was estimated. The epitaxial relation with the Si substrate also retards the C49–C54 phase transformation. The epitaxial growth of C49–TiSi2 on the Si substrate is observed in a large portion of C49–TiSi2 grains in the sample without PAI, whereas orientation of C49–TiSi2 in the sample with PAI has no relation to that of the Si substrate. Epitaxial C49–TiSi2 is more stable and is difficult to phase transform. After phase transformation, the C54–TiSi2 oriented to the 〈004〉 direction is predominant in the samples without PAI. The strong orientation of C54〈004〉 resulted from one-dimensional growth along submicron lines enhanced by the low density of the nucleation site. On the other hand, in the sample with PAI, an increase in the nucleation site leads to two-dimensional growth, and C54–TiSi2 films exhibit a random orientation with a weak dominant C54〈311〉 orientation. © 1999 American Institute of Physics.  
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61.72.up Other materials
61.82.Fk Semiconductors
85.40.Ry Impurity doping, diffusion and ion implantation technology
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
61.80.Jh Ion radiation effects
64.70.K- Solid-solid transitions
61.72.Cc Kinetics of defect formation and annealing

Thermally stimulated-current observation of hole traps in undoped semi-insulating GaAs and their photoquenching behavior

Maki Suemitsu, Yoshitomo Sagae, and Nobuo Miyamoto

J. Appl. Phys. 85, 3139 (1999); http://dx.doi.org/10.1063/1.369653 (3 pages) | Cited 2 times

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Detailed thermally stimulated-current measurements have been conducted on an undoped, semi-insulating GaAs crystal under 1.06 μm illumination at 15 K. By combining with Hall voltage measurements, we confirmed the presence of hole traps that show similar activation energies with the one proposed for the actuator level in the deep acceptor-mediated photoquenching model of EL2 [Suemitsu et al., Phys. Rev. B 52, 1666 (1995)]. The observed quenching of these hole traps suggests that the actuator level be, most likely, a part of the metastable complex. © 1999 American Institute of Physics.
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71.55.Eq III-V semiconductors
77.22.Ej Polarization and depolarization
72.40.+w Photoconduction and photovoltaic effects
81.05.Ea III-V semiconductors
72.80.Ey III-V and II-VI semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.20.My Galvanomagnetic and other magnetotransport effects

Structural and tribological characterization of protective amorphous diamond-like carbon and amorphous CNx overcoats for next generation hard disks

T. W. Scharf, R. D. Ott, D. Yang, and J. A. Barnard

J. Appl. Phys. 85, 3142 (1999); http://dx.doi.org/10.1063/1.369654 (13 pages) | Cited 85 times

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Further insight into processing-structure-property relationships have been carried out for existing and candidate carbon-based protective overcoats used in the magnetic recording industry. Specifically, 5 nm thick amorphous diamond-like carbon (a:C) and nitrogenated diamond-like carbon (a:CNx) overcoats were deposited by low deposition rate sputtering onto a thin film disk consisting of either CoCrPt/CrV/NiP/AlMg or CoCrPt/CrV/glass. The wear durability and frictional behavior of these hard disks were ascertained using a recently developed depth sensing reciprocating nanoscratch test. It was determined that the CN0.14/CoCrPt/CrV/glass disk exhibited the most wear resistance, least amount of plastic deformation, and lowest kinetic friction coefficient after the last wear event. Core level x-ray photoelectron spectroscopy (XPS) results of sputter cleaned overcoats indicated that nitrogen up to 14 at. % incorporated into the amorphous network resulted in these improvements near the overcoat/magnetic layer interface, since there was an increase in the number of N-sp3 C bonded sites in a predominantly N-sp2 C bonded matrix. However, nonsputter cleaned overcoats exhibited a more graphitic pyridine-like (nondoping configuration) structure near the surface as evidenced by the increase in C�N versus C–N bonds and the valence band XPS determined appearance of the 2p-π band near the Fermi level (EF). Therefore, XPS sputter cleaning revealed a gradient in the chemical nature of the overcoats through the thickness. In addition, micro-Raman spectroscopy established that a further increase of nitrogen (⩾18 at. %) weakened the overcoat structure due to the formation of terminated sites in the amorphous carbon network, since nitrogen failed to connect the sp2 domains within the network. This, in conjunction with an increase in the intensity of the 2p-π band from the valence band XPS spectra and the increase in the G-band position and ID/IG ratio from the Raman spectra, confirmed the increase in the size and number of sp2 bonds in the CN0.18 overcoat. © 1999 American Institute of Physics.
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68.60.Bs Mechanical and acoustical properties
68.35.Gy Mechanical properties; surface strains
68.55.-a Thin film structure and morphology
61.43.Er Other amorphous solids
78.35.+c Brillouin and Rayleigh scattering; other light scattering
78.66.Jg Amorphous semiconductors; glasses
81.65.Cf Surface cleaning, etching, patterning
79.60.Dp Adsorbed layers and thin films
79.60.Ht Disordered structures
62.20.Qp Friction, tribology, and hardness
81.40.Pq Friction, lubrication, and wear

Structural transformations of Bi2CuO4 induced by mechanical deformation

X. L. Chen, J. K. Liang, Y. Liu, Y. C. Lan, Y. L. Zhang, Y. Ma, G. C. Che, G. D. Liu, X. Y. Xing, and X. Y. Qiao

J. Appl. Phys. 85, 3155 (1999); http://dx.doi.org/10.1063/1.369692 (4 pages) | Cited 4 times

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Structural transformation of α-Bi2CuO4 (a = 8.4996 Å, c=5.8172 Å, space group P4/ncc) during ball milling was investigated by powder x-ray diffraction and thermal analysis. It is shown that α-Bi2CuO4 first transforms into an amorphous phase; and then transforms into a new phase (designated by β-Bi2CuO4) with milling time. The new phase appears to be isostructural to (La,Sr)2CuO4 and has a tetragonal cell with cell parameters a=3.869 and c=13.83 Å. It is a metastable phase which can transform back into α-Bi2CuO4 at 650 °C. No superconductivity was observed above 5 K for both as-milled samples and oxygen-annealed β-Bi2CuO4. © 1999 American Institute of Physics.
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81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
64.70.K- Solid-solid transitions
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
61.43.Er Other amorphous solids

Thermal stress in a trigonal crystal rod

Charles E. Greninger and Sergio E. Rodriguez

J. Appl. Phys. 85, 3159 (1999); http://dx.doi.org/10.1063/1.369655 (9 pages) | Cited 3 times

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The thermally induced stresses and strains in a freely supported long trigonal crystal rectangular rod are presented. Careful grouping of the stress, strain relationships casts the equations into the form of the usual logarithmic potential solution with new coefficients that are simple functions of the stiffness matrix elements. Then a logarithmic potential solution is used to find analytic expressions for the particular stresses. Addition of two ordinary isothermal stress fields allows the particular stresses to be corrected so that (a) the surface stresses average to zero on each lateral boundary and (b) the plane strain condition is removed and the average longitudinal stress and its moments are zero. A method to zero the residual surface stress is mentioned and numerical test cases and an example are given. © 1999 American Institute of Physics.
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62.20.F- Deformation and plasticity
62.20.D- Elasticity
46.35.+z Viscoelasticity, plasticity, viscoplasticity
46.70.Hg Membranes, rods, and strings

Influence of anisotropic surface diffusivity on electromigration induced void migration and evolution

D. R. Fridline and A. F. Bower

J. Appl. Phys. 85, 3168 (1999); http://dx.doi.org/10.1063/1.369656 (7 pages) | Cited 30 times

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Microelectronic circuits often fail because of voids and cracks that cause open circuits in their interconnects. The voids form due to severe thermal stresses and high current densities present in the lines during service. Typical interconnect lines contain large numbers of voids which gradually grow and change their shape during the life of the line. It has been observed that many open circuits occur when a round void collapses into a slit perpendicular to the direction of electric current flow. O. Kraft and E. Arzt [Acta Mater. 45, 1599 (1997)] have shown that these slits may be caused by electromigration induced surface diffusion. Anisotropy in the surface diffusivity plays a key role in the formation of slit voids. In this article, our objective is to present a detailed parametric study of electromigration induced void evolution in interconnects. We idealize an interconnect as a two-dimensional electrically conducting strip which contains an initially semi-circular void. We neglect the stresses for simplicity. A finite element method is used to predict the evolution of the void after an electric field is applied to the strip. It is shown that the void may: (i) Evolve to a stable shape as it migrates down the line; (ii) break up into several smaller voids or separate from the boundary; (iii) form a slit which severs the strip. The conditions necessary for each type of behavior are explored in detail. The implications on interconnect reliability are discussed. © 1999 American Institute of Physics.
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85.40.Ls Metallization, contacts, interconnects; device isolation
66.30.Qa Electromigration
68.35.Fx Diffusion; interface formation
61.72.Qq Microscopic defects (voids, inclusions, etc.)

Mo/SiO2 multilayers for soft x-ray optical applications

Feng-ping Wang, Pei-xuan Wang, Kun-quan Lu, Zheng-zhi Fang, Min Gao, Xiao-feng Duan, Ming-qi Cui, Hong-ji Ma, and Xiao-ming Jiang

J. Appl. Phys. 85, 3175 (1999); http://dx.doi.org/10.1063/1.369657 (5 pages)

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The optimal reflectivity of soft-x-ray multilayers made of new pairs of materials was theoretically calculated in the wavelength range of 2.0–4.5 nm. Molybdenum and silicon dioxide were then selected for “high index” and “low index” layer, respectively, in the multilayer system. The microstructures and composition profiles of multilayers of molybdenum and silicon dioxide were investigated by means of low-angle x-ray diffraction, cross-sectional high resolution electron microscopy, an energy-filtering transmission electron microscope elemental mapping, and Auger electron spectrometry. The results show that no diffusion of Si into Mo layers has occurred, and only slight diffusion of O into Mo layers are seen. Sharp and relatively smooth interfaces have formed. With increasing number of layers, the interfacial roughness was propagated through the multilayer stack and low-frequency roughness increases while the high-frequency roughness decreases. © 1999 American Institute of Physics.
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07.85.-m X- and γ-ray instruments
42.79.Wc Optical coatings
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.35.Ct Interface structure and roughness
68.55.Nq Composition and phase identification
81.15.Cd Deposition by sputtering
68.35.Fx Diffusion; interface formation
FREE

X-ray studies of polymer/gold nanocomposites

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

J. Appl. Phys. 85, 3180 (1999); http://dx.doi.org/10.1063/1.369658 (5 pages) | Cited 19 times

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We demonstrate that x-ray reflection standing wave fluorescence spectroscopy is a highly sensitive technique for the determination of the distribution of metal nanoparticles inside polymer thin films. We investigate both the depth profile and the in-plane spatial correlation of gold nanoparticles in an asymmetric polystyrene-b-poly(2-vinylpyridine) block copolymer film. These copolymer films self-assemble into alternating, nanometer-sized domains that are, upon annealing, selectively decorated by thermally evaporated metal nanoparticles to form metal/polymer composites. © 1999 American Institute of Physics.
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68.55.-a Thin film structure and morphology
61.46.-w Structure of nanoscale materials
81.07.-b Nanoscale materials and structures: fabrication and characterization
82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods
61.41.+e Polymers, elastomers, and plastics
81.40.Gh Other heat and thermomechanical treatments

On the kinetic mechanism of grain boundary wetting in metals

E. E. Glickman and M. Nathan

J. Appl. Phys. 85, 3185 (1999); http://dx.doi.org/10.1063/1.369659 (7 pages) | Cited 16 times

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The thermodynamic condition characteristic of grain boundary wetting (GBW) causes an imbalance between grain boundary (GB) and solid–liquid interphase surface tensions γGB and γSL. This creates in turn a force acting at the root of the GB groove, and pointing into the solid. The “indentation” action of this force is suggested to cause stress-driven self-diffusion into the GB. This process removes the solid atoms from the groove cavity and causes their deposition along the GB (“internal solution”). Assuming that the GB acts as a perfect sink, this “self-indentation-internal solution” mechanism can account for a number of GBW features: the non-Mullins grooving morphology and linear kinetics, the origin of the singular stress field at the wetting front, the expansion of the solid under GBW, the influence of external stress on GBW, the GBW transitions with temperature, and the fast atomic penetration of the liquid metal ahead of the groove root. © 1999 American Institute of Physics.
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61.72.Mm Grain and twin boundaries
68.08.Bc Wetting
66.30.Fq Self-diffusion in metals, semimetals, and alloys
65.20.-w Thermal properties of liquids
65.40.gd Entropy

Microstructures of GaN1−xPx layers grown on (0001) GaN substrates by gas source molecular beam epitaxy

Tae-Yeon Seong, In-Tae Bae, Chel-Jong Choi, D. Y. Noh, Y. Zhao, and C. W. Tu

J. Appl. Phys. 85, 3192 (1999); http://dx.doi.org/10.1063/1.369693 (6 pages) | Cited 7 times

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Transmission electron microscope (TEM), transmission electron diffraction (TED), and synchrotron x-ray diffraction (XRD) studies have been performed to investigate microstructural behavior of gas source molecular beam epitaxial GaN1−xPx layers grown on (0001) GaN/sapphire at temperatures (Tg) in the range 500–760 °C. TEM, TED, and XRD results indicate that the samples grown at Tg ⩽ 600 °C undergo phase separation resulting in a mixture of GaN-rich and GaP-rich GaNP with zinc-blende structure. However, the samples grown at Tg ≥ 730 °C are found to be binary zinc-blende GaN(P) single crystalline materials. As for the 500 °C layer, the two phases are randomly oriented and distributed, whereas the 600 °C layer consists of phases that are elongated and inclined by 60°–70° clockwise from the [0001]α-GaN direction. The samples grown at Tg ≥ 730 °C are found to consist of two types of microdomains, namely, GaN(P)I and GaN(P)II; the former having twin relation to the latter. © 1999 American Institute of Physics.
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68.55.-a Thin film structure and morphology
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
61.66.Fn Inorganic compounds
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