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1.
X.H. Zhu H.L.W. Chan C.-L. Choy K.-H. Wong D. Hesse 《Applied Physics A: Materials Science & Processing》2006,82(4):709-713
We report a comparative study of the microstructure of compositionally graded (Ba1-xSrx)TiO3 (BST) films with two compositionally graded directions, up and down, with respect to the substrate, which were deposited
epitaxially on (La,Sr)CoO3 (LSCO)-covered MgO(100) single-crystal substrates by pulsed laser deposition. Cross-sectional transmission electron microscopy
(TEM) images and electron diffraction show that the graded films grow epitaxially with their (100) plane parallel to the (100)
surface of the MgO single-crystal substrate, and with an in-plane orientation relationship of 〈001〉BST//〈001〉LSCO//〈001〉MgO. The crystalline quality and surface morphology of the graded films are closely related to the direction of the compositional
gradient built into the graded films. Down-graded films (starting with a BaTiO3 layer at the film/substrate interface) have a much better crystalline quality and a smoother surface than the up-graded films
(starting with a (Ba0.75Sr0.25)TiO3 layer at the film/substrate interface). Obviously, the BaTiO3 bottom layer in the down-graded film acts not only as a part of the graded film but also as an excellent seeding layer to
enhance the crystallization of the subsequent film layers, resulting in a high crystalline quality of the down-graded film
and an enhanced dielectric behavior. Planar (high-resolution) TEM images also demonstrate that down-graded films have a larger,
and more uniform, grain size than up-graded films, and that the latter contain voids.
PACS 81.15.-z; 77.55.+f; 68.37.Lp; 61.14.-x 相似文献
2.
N. K. Deepak 《Pramana》2010,74(3):421-440
The channelling and scattering yields of 1 MeV α-particles in the 〈100〉, 〈110〉 and 〈111〉 directions of silicon implanted with bismuth and ytterbium have been simulated using
N-body model. The close encounter yield from dopant atoms in silicon is determined from the flux density, using the Bontemps
and Fontenille method. All previous works reported in literature so far have been done with computer programmes using a statistical
analytical expression or by a binary collision model or a continuum model. These results at the best gave only the transverse
displacement of the lattice site from the concerned channelling direction. Here we applied the superior N-body model to study the yield from bismuth in silicon. The finding that bismuth atom occupies a position close to the silicon
substitutional site is new. The transverse displacement of the suggested lattice site from the channelling direction is consistent
with the experimental results. The above model is also applied to determine the location of ytterbium in silicon. The present
values show good agreement with the experimental results. 相似文献
3.
High dose implantations (1016 ions/cm2) of antimony in silicon result in concentrations far above the solid solubility of antimony in silicon. Rutherford backscattering
was used to study the behaviour of damage and antimony concentration profiles for 〈100〉 and 〈111〉 substrates. The measurements
were performed for various annealing treatments, implantation temperatures and implantation energies. A crystal orientation
dependent outdiffusion of antimony towards the surface, a highly supersaturated phase of substitutional antimony at 600°C
and a strong reverse annealing effect at higher temperatures were found. 相似文献
4.
The study reported in this paper contributes to better understanding the thermal oxidation effect on structural and optical
properties of polycrystalline silicon heavily in situ P-LPCVD films. The deposits, doped at levels 3×1019 and 1.6×1020 cm−3, have been elaborated from silane decomposition (400 mTorrs, 605°C) on monosilicon substrate oriented 〈111〉. The thermal
oxidation was performed at temperatures: 850°C during 1 hour, 1000, 1050, and 1100°C during 15 minutes. The XRD spectra analysis
pointed out significant 〈111〉 texture evolution, while in the case of 〈220〉 and 〈311〉 textures, the intensities are practically
invariant (variations fall in the uncertainty intervals). The optical characterizations showed that refractive index and absorption
coefficient are very sensitive to the oxidation treatment, mainly when the doping level is not very high. We think that atomic
oxygen acts as defects passivating agent leading to carriers’ concentration increasing. Besides, the optical behavior is modeled
in visible and near infrared, by a seven-term polynomial function n
2=f(λ
2), with alternate signs, instead of theoretically unlimited terms number from Drude’s model. It has been shown that fitting
parameters fall on Gaussian curves like they do in the theoretical model. 相似文献
5.
Systems containing single domain magnetic particles are of great interest in view of their possible applications in ultrahigh-density data storage and magnetoelectronic devices. The focus of this work is plan-view STEM Z-contrast imaging study of the self-assembly growth of magnetic nickel nanostructures by domain matching epitaxy under Volmer–Weber (V–W) mode. The growth was carried out using pulsed laser deposition (PLD) technique with epitaxial titanium nitride film as the template, which was in turn grown on silicon (001) substrate via domain matching epitaxy. Our results show that the base of nickel islands is rectangular with the two principal edges parallel to two orthogonal 〈110〉 directions, which is [110] and [] for [001] oriented growth. The size distribution of the islands is relatively narrow, comparable to that obtained from self-assembled islands grown under Stranski–Krastanow (S–K) mode. A certain degree of self-organization was also found in the lateral distribution of islands: island chains were observed along the directions close to 〈011〉, which are also the edge directions. The interaction between neighboring islands through the island edge-induced strain field is believed to be responsible for the size uniformity and the lateral ordering.An erratum to this article can be found at 相似文献
6.
Bhaskaran M Sriram S Perova TS Ermakov V Thorogood GJ Short KT Holland AS 《Micron (Oxford, England : 1993)》2009,40(1):89-93
This article reports on the in situ analysis of nickel silicide (NiSi) thin films formed by thermal processing of nickel thin films deposited on silicon substrates. The in situ techniques employed for this study include micro-Raman spectroscopy (microRS) and X-ray diffraction (XRD); in both cases the variations for temperatures up to 350 degrees C has been studied. Nickel silicide thin films formed by vacuum annealing of nickel on silicon were used as a reference for these measurements. In situ analysis was carried out on nickel thin films on silicon, while the samples were heated from room temperature to 350 degrees C. Data was gathered at regular temperature intervals and other specific points of interest (such as 250 degrees C, where the reaction between nickel and silicon to form Ni(2)Si is expected). The transformations from the metallic state, through the intermediate reaction states, until the desired metal-silicon reaction product is attained, are discussed. The evolution of nickel silicide from the nickel film can be observed from both the microRS and XRD in situ studies. Variations in the evolution of silicide from metal for different silicon substrates are discussed, and these include (100) n-type, (100) p-type, and (110) p-type silicon substrates. 相似文献
7.
Summary The dislocation relaxation maximum has been investigated at frequencies of 5, 10 and 30 MHz. The three (very high-purity)
silver crystals of crystallographic orientation 〈111〉, 〈110〉 and 〈100〉 which are given a resolved shear stress of 20 MPa were
found to produce dislocation relaxation maximum at 107 K in all the three samples. The maximum shifts to 117 K when measurement
is carried out at 10 MHz and to 127 K at 30 MHz. The results reveal that the maximum is orientation independent. The activation
energy and the attempt frequency were calculated and found to be equal to 0.105 eV and 2·109 Hz, respectively. Meanwhile the larger magnitude of the maximum was found on the 〈111〉 crystal and the least was on the 〈100〉
crystal. Finally, it was clearly shown that the dislocation relaxation strength decreases as the frequency increases. 相似文献
8.
Electronic band structure and energetic stability of two types of 〈110〉 and 〈001〉 oriented silicon nanowires in β-Sn phase
with the surface terminated by hydrogen atoms were studied using density functional theory. It was found that β-Sn nanowires
are metastable with zero band gap against to nanowires in diamond phase. The relative energy of the studied wires tends to
the energy of the bulk silicon crystal in β-Sn phase. 相似文献
9.
Bhaskaran M Sriram S Mitchell DR Short KT Holland AS Mitchell A 《Micron (Oxford, England : 1993)》2009,40(1):11-14
This article discusses the results of transmission electron microscopy (TEM)-based investigation of nickel silicide (NiSi) thin films grown on silicon. Nickel silicide is currently used as the CMOS technology standard for local interconnects and in electrical contacts. Films were characterized with a range of TEM-based techniques along with glancing angle X-ray diffraction. The nickel silicide thin films were formed by vacuum annealing thin films of nickel (50 nm) deposited on (100) silicon. The cross-sectional samples indicated a final silicide thickness of about 110 nm. This investigation studied and reports on three aspects of the thermally formed thin films: the uniformity in composition of the film using jump ratio maps; the nature of the interface using high resolution imaging; and the crystalline orientation of the thin films using selected-area electron diffraction (SAED). The analysis highlighted uniform composition in the thin films, which was also substantiated by spectroscopy techniques; an interface exhibiting the desired abrupt transition from silicide to silicon; and desired and preferential crystalline orientation corresponding to stoichiometric NiSi, supported by glancing angle X-ray diffraction results. 相似文献
10.
V. V. Shagaev 《Physics of the Solid State》1998,40(11):1892-1895
Analytical expressions are derived for the derivatives of the frequencies of magnetostatic waves with respect to the external
magnetic field in anisotropic ferromagnetic films. Films having cubic anisotropy and 〈100〉, 〈110〉, and 〈111〉 surfaces are
analyzed in detail. The frequency-field relations are used in an experimental determination of the temperature coefficients
of the cubic anisotropy field and the saturation magnetization in an yttrium iron garnet film.
Fiz. Tverd. Tela (St. Petersburg) 40, 2089–2092 (November 1998) 相似文献
11.
This article discusses the formation and detailed materials characterisation of nickel silicide thin films. Nickel silicide thin films have been formed by thermally reacting electron beam evaporated thin films of nickel with silicon. The nickel silicide thin films have been analysed using Auger electron spectroscopy (AES) depth profiles, secondary ion mass spectrometry (SIMS), and Rutherford backscattering spectroscopy (RBS). The AES depth profile shows a uniform NiSi film, with a composition of 49-50% nickel and 51-50% silicon. No oxygen contamination either on the surface or at the silicide-silicon interface was observed. The SIMS depth profile confirms the existence of a uniform film, with no traces of oxygen contamination. RBS results indicate a nickel silicide layer of 114 nm, with the simulated spectra in close agreement with the experimental data. Atomic force microscopy and transmission electron microscopy have been used to study the morphology of the nickel silicide thin films. The average grain size and average surface roughness of these films was found to be 30-50 and 0.67 nm, respectively. The film surface has also been studied using Kikuchi patterns obtained by electron backscatter detection. 相似文献
12.
G. Foti E. Rimini G. Vitali M. Bertolotti 《Applied Physics A: Materials Science & Processing》1977,14(2):189-191
Reflection high energy electron diffraction has been used to investigate the amorphous to polycrystalline structure transition
in silicon induced by laser pulse. The power density of the ruby laser pulse, in the free generation mode, has been maintained
below the threshold to induce surface damage. Depth analysis has been carried out in 〈100〉 silicon crystal using the channeling
effect technique. 相似文献
13.
?. Tüzün A. Slaoui C. Maurice S. Vallon 《Applied Physics A: Materials Science & Processing》2010,99(1):53-61
In this work, we present extended structural properties of poly-Si thin films fabricated by aluminium-induced crystallization
(AIC) of amorphous silicon (a-Si) on high-temperature glass-ceramic substrates. The silicon nucleation kinetics on glass-ceramic
substrates was investigated by optical microscopy. The crystalline quality of the films was studied by micro-Raman spectroscopy
as a function of exchange annealing conditions. By means of electron backscattering diffraction (EBSD), we have analyzed the
effect of thermal annealing on silicon grain size and its distribution, intra- and inter-grains defects, and on the grains
preferential crystallographic orientation. The optimal thermal annealing condition, allowing 100% crystallized polysilicon
large grains with an average grain size of 26 μm and 〈100〉 oriented, acquired a thermal budget of 475°C and 8 h. 相似文献
14.
T. Shimizu S. Senz S. Shingubara U. Gösele 《Applied Physics A: Materials Science & Processing》2007,87(4):607-610
The synthesis of epitaxial Si nanowires with growth direction parallel to Si [100] on Si(100) substrate was demonstrated using
a combination of anodic aluminum oxide (AAO) template, catalytic gold film sandwiched between the template and the Si(100)
substrate and vapor-liquid-solid growth using SiH4 as the Si source. After growing out from the AAO nanopores, most Si nanowires changed their diameter and growth direction
into larger diameter and 〈111〉 direction.
PACS 81.07.-b; 82.45.Cc 相似文献
15.
Wenwei Ge Hong Liu Xiangyong Zhao Xiaobing Li Xiaoming Pan Di Lin Haiqing Xu Xiangping Jiang Haosu Luo 《Applied Physics A: Materials Science & Processing》2009,95(3):761-767
In this paper, a single crystal of 0.96Na0.5Bi0.5TiO3-0.04BaTiO3 with dimensions of Φ 30×10 mm was grown by the top-seeded-solution growth method. X-ray powder diffraction results show that the as-grown crystal
possesses the rhombohedral perovskite-type structure. The dielectric, piezoelectric and electrical conductivity properties
were systematically investigated with 〈001〉, 〈110〉 and 〈111〉 oriented crystal samples. The room-temperature dielectric constants
for the 〈001〉, 〈110〉 and 〈111〉 oriented crystal samples are found to be 650, 740 and 400 at 1 kHz. The (T
m, ε
m) values of the dielectric temperature spectra are almost independent of the crystal orientations; they are (306°C, 3718),
(305°C, 3613) and (307°C, 3600) at 1 kHz for the 〈001〉, 〈110〉 and 〈111〉 oriented crystal. The optimum poling conditions were
obtained by investigating the piezoelectric constants d
33 as a function of poling temperature and poling electric field. For the 〈001〉 and 〈110〉 crystal samples, the maximum d
33 values of 146 and 117 pC/N are obtained when a poling electric field of 3.5 kV/mm and a poling temperature of 80°C were applied
during the poling process. The as-grown 0.96Na0.5Bi0.5TiO3-0.04BaTiO3 crystal possesses a relatively large dc electrical conductivity, especially at higher temperature, having a value of 1.98×10−11 Ω−1⋅m−1 and 3.95×10−9 Ω−1⋅m−1 at 25°C and 150°C for the 〈001〉 oriented crystal sample. 相似文献
16.
A study has been carried out of the temperature dependences of luminescence spectra on a large number of CdTe/ZnTe structures
differing in average thickness, 〈L
z〉=0.25–4 monolayers (ML), and CdTe layer geometry (continuous, island type). The influence of geometric features in the structure
of ultrathin layers on linewidth, the extent of lateral localization of excitons, their binding energy, and exciton-phonon
coupling is discussed. It is shown that in island structures there is practically no lateral exciton migration. The exciton-phonon
coupling constant in a submonolayer structure has been determined, Γph=53 meV, and it is shown that in structures with larger average thicknesses Γph is considerably smaller. Substantial lateral exciton migration was observed to occur in a quantum well with 〈L
z〉=4 ML, and interaction with acoustic phonons was found to play a noticeable part in transport processes. It has been established
that the depth of the exciton level in a quantum well and structural features of an ultrathin layer significantly affect the
temperature dependences of integrated photoluminescence intensity.
Fiz. Tverd. Tela (St. Petersburg) 41, 717–724 (April 1999) 相似文献
17.
M.?V.?Dorokhin S.?V.?Za?tsev A.?S.?Brichkin O.?V.?Vikhrova Yu.?A.?Danilov B.?N.?Zvonkov V.?D.?Kulakovski? M.?M.?Prokof’eva A.?E.?Sholina 《Physics of the Solid State》2010,52(11):2291-2296
The circular polarization of low-temperature electroluminescence of diodes based on heterostructures with an undoped quantum
well InGaAs/GaAs and a delta〈Mn〉 layer in the GaAs barrier has been investigated. The possibility of changing the degree of
circular polarization of the electroluminescence by varying the main structural parameters of diodes (spacer layer thickness,
i.e., the distance between the delta〈Mn〉 layer and the quantum well, atomic concentration in the delta〈Mn〉 layer, and introduction
of an additional acceptor delta layer) has been analyzed. It has been revealed that the variation in the spacer layer thickness
is the most effective method for controlling the degree of circular polarization of the electroluminescence. 相似文献
18.
The formation and destruction of the surface silicide on W(100) after cleaning of the sample surface and bulk in various regimes
is studied by high-resolution Auger electron spectroscopy. It is shown that the cleanness of the bulk has practically no influence
on the laws governing the formation of the surface silicide when Si atoms are adsorbed on a heated W surface and that almost
up to completion of its formation all the silicon atoms impinging on the surface, from the very first, remain on it and are
incorporated into the surface silicide. The destruction of the surface silicide depends in a definite manner on the state
of the bulk, and at T=1400 K it is apparently limited in the early stages by the passage of Si atoms from the surface to the subsurface layer and
in subsequent stages by the diffusion of silicon within the substrate. The bulk silicon density that limits the destruction
of the surface silicide is estimated.
Zh. Tekh. Fiz. 67, 137–140 (July 1997) 相似文献
19.
Transition to single crystal of polycrystalline Si material underlying a Si crystal substrate of 〈100〉 orientation was obtained
via laser irradiation. The changes in the structure were analyzed by reflection high energy electron diffraction and by channeling
effect technique using 2.0 MeV He Rutherford scattering. The power density required to induce the transition in a 4500 ? thick
polycrystalline layer is about 70 MW/cm2 (50ns). The corresponding amorphous to single transition has a threshold of about 45 MW/cm2. 相似文献
20.
Prashant Kumar 《Applied Physics A: Materials Science & Processing》2010,98(2):473-479
DC electric-field mediated nanocrystallization of thermally evaporated silicon thin films with nickel as seed/cap layer has
been attempted in complete absence of any external heat input. When 60 nm Si thin film coated onto 5 nm Ni thin film was treated
by a direct current (DC) electric field (up to 3.3 kV/cm up to 5 minutes) after the deposition, amorphous silicon thin films
became nanocrystalline (6–10 nm). Silicon nanograins (average diameter 90 nm) grow to larger sizes (average diameter 240 nm)
with sharpening of grain size distribution. Huge grain growth (4-fold increase) has been observed when nickel was used as
cap layer (5 nm Ni/60 nm Si). XRD data show the signature of nickel silicide formation on the surface in nickel cap layer
case. Field treatment has changed the optical absorption edge (shifts left in nm units) and the refractive index of silicon
thin film when nickel was used as under layer, and an almost negligible effect on the optical properties has been observed
when nickel was used as cap layer. 相似文献