Silicon Specimens Research Articles

Role of silicon content and final annealing temperature on microtexture and microstructure development in non-oriented silicon steel

A matrix of 12 iron–silicon specimens were investigated to identify the microtextures, grain misorientations and grain size distributions present and to relate them to the various silicon contents and annealing cycles. The steel grades examined contained either 1.0, 2.4 or 3 wt.% silicon. Three specimens were hot rolled only at 1100 °C and the remaining nine specimens, with various silicon levels, were given batch annealing heat treatments in the laboratory at the temperatures of 650, 700 or 750 °C. The results showed that the higher strain levels present in the hot rolled microstructures as silicon content increased created a greater driving force for recovery, recrystallisation and grain growth processes. The final grain size distributions were analysed in detail. With regard to textures the general trend in microtexture formation was dictated mainly by the level of rolling in the ferritic region, which had taken place.

Molecular Dynamics Simulation on the Mechanism of Nanometric Machining of Single-Crystal Silicon

Molecular dynamics (MD) simulation can play a significant role in addressing a number of machining problems at the atomic scale. This simulation, unlike other simulation techniques, can provide new data and insights on nanometric machining; which cannot be obtained readily in any other theory or experiment. In this paper, some fundamental problems of mechanism are investigated in the nanometric cutting with the aid of molecular dynamics simulation, and the single-crystal silicon is chosen as the material. The study showed that the purely elastic deformation took place in a very narrow range in the initial stage of process of nanometric cutting. Shortly after that, dislocation appeared. And then, amorphous silicon came into being under high hydrostatic pressure. Significant change of volume of silicon specimen is observed, and it is considered that the change occur attribute to phase transition from a diamond silicon to a body-centered tetragonal silicon. The study also indicated that the temperature distributing of silicon in nanometric machining exhibited similarity to conventional machining.

Anisotropy in fracture of single crystal silicon film characterized under uniaxial tensile condition

In this work, we studied the effect of crystallographic orientation on fracture toughness and fracture paths of single crystal silicon film by a uniaxial tensile test. A focused ion beam (FIB) process was used to introduce a notch in the middle of silicon (1 1 0) and (0 0 1) film specimens that have different tensile orientations. The fracture toughness value varied from 1 to 2 MPa m 1/2, depending on the tensile orientation. The scanning electron microscope (SEM) observations suggested that the inclination angle of the low index planes, {1 1 1} and {1 1 0}, relative to the specimen surface affects the fracture path significantly. The {1 1 1} and {1 1 0} planes were the preferred cleavage planes.

Quantum confinement contribution to porous silicon photoluminescence spectra

Photoluminescence (PL) spectra of freshly etched and ambient-aged porous silicon specimens have been measured and analyzed to extract spectral contributions due to quantum confinement (QC) and non-QC effects. It is shown that all spectra can be deconvolved into five Gaussian bands with typical peak energies 1.59, 1.76, 1.84, 1.94, and 2.07 eV. Ambient aging induces ∼0.1 eV blueshift in each of the three highest energy peaks, which is attributed to QC effects. In contrast, the two lowest energy peaks remain unshifted as expected for non-QC effects. Because size of the porous silicon nanoparticles is deduced from the magnitude of blueshift, it is imperative to correctly identify the spectral components associated solely with QC. The three closely spaced Gaussian bands are summed and the resulting single Gaussian band is analyzed with the model of Islam and Kumar [J. Appl. Phys. 93, 1753 (2003)]. Results show that peak energy of the freshly etched sample is 1.86 eV with average nanoparticle size L0=3.90 nm and dispersion σ=0.065 nm. Ambient aging for 40 days causes this peak to blueshift to 2.07 eV and reduces the nanoparticle size to L0=3.37 nm with dispersion σ=0.088 nm. The reduction in particle size (ΔL=0.53 nm) is attributed to oxidation of the nanocrystalline surface, and corresponds to approximately 2 monolayers of oxide growth.

MEMS 공정을 이용한 단결정 실리콘 미세 인장시편과 미세 변형 측정용 알루미늄 Marker의 제조

Micro tensile test specimens of thin film single crystal silicon for the most useful structural materials in MEMS (Micro Electro Mechanical System) devices were fabricated using SOI (Silicon-on-Insulator) wafers and MEMS processes. Dimensions of micro tensile test specimens were thickness of <TEX>$7\mu\textrm{m}$</TEX>, width of 50~<TEX>$350\mu\textrm{m}$</TEX>, and length of 2mm. Top and bottom silicon were etched using by deep RIE (Reactive Ion Etching). Thin film aluminum markers on testing region of specimens with width of <TEX>$5\mu\textrm{m}$</TEX>, lengths of 30~<TEX>$180\mu\textrm{m}$</TEX> and thickness of 200 nm for measuring tensile strain were fabricated by aluminum wet etching method. Fabricated side wall angles of aluminum marker were about <TEX>$45^{\circ}~50^{\circ}$</TEX>. He-Ne laser with wavelength of 633nm was used for checking fringed patterns.

Off-axis electron holography of electrostatic potentials in unbiased and reverse biased focused ion beam milled semiconductor devices.

Off-axis electron holography in the transmission electron microscope (TEM) is used to measure two-dimensional electrostatic potentials in both unbiased and reverse biased silicon specimens that each contain a single p-n junction. All the specimens are prepared for examination in the TEM using focused ion beam (FIB) milling. The in situ electrical biasing experiments make use of a novel specimen geometry, which is based on a combination of cleaving and FIB milling. The design and construction of an electrical biasing holder are described, and the effects of TEM specimen preparation on the electrostatic potential in the specimen, as well as on fringing fields beyond the specimen surface, are assessed.

From crack deflection to lattice vibrations—macro to atomistic examination of dynamic cleavage fracture

A set of cleavage experiments with strip-shaped single-crystal silicon specimens subjected to three-point bending is reported. The experiments enabled examination of the relationships between the dynamic energy release rate, the velocity, the orientation-dependent cleavage energy, and the cleavage plane of propagation. Dynamic crack propagation experiments show that when a [0 0 1] silicon single crystal is fractured under three-point bending at ‘parallel’ velocity (directly measured at the bottom surface of the specimen) of up to 1500 m/ s , it prefers to cleave along the vertical (1 1 0) plane, while when the specimen is fractured under the same conditions but at a velocity higher than 2900 m/ s , it cleaves along the inclined (1 1 1) plane. At intermediate velocities, the crack will deflect from the (1 1 0) plane to the (1 1 1) plane. Crack velocity was determined by the initial notch length. The local (calculated) velocity of deflection between the cleavage planes ranges from 2900 m/ s , for a crack propagating on the (1 1 0) plane in the [1 1 ̄ 0] direction, to about 30 m/ s , for a crack on the (1 1 0) plane, but in the [0 0 1] direction. It is suggested that the cause of the deflection phenomenon is the anisotropic, velocity-dependent cleavage energy, resulted phonon radiation caused by anisotropic, velocity-dependent lattice vibrations. We have studied the effect of material properties and propose selection criteria to explain the deflection phenomenon: the crack will deflect to the plane of least-energy, for which G− Γ i ( V)=max, or to the plane with maximum crack tip velocity, V i ( Γ)=max.

Non-linear dynamical analysis of crack surface perturbations and their dependence on velocity and direction

The fracture surfaces of single crystal [1 0 0] silicon specimens, fractured under three-point bending (3PB) and subjected to a high strain energy upon cracking, revealed exceptional surface perturbations, generated during the unstable propagation. While macroscopically the crack is propagating on the (1 1 1) low energy cleavage plane, microscopic examination revealed small angled deviations from and fluctuations along that plane. Furthermore, while the crack is propagating at a velocity of nearly 3000 m/s in the [1 1 ̄ 0] direction, its velocity in the [1 1 2 ̄ ] direction is two orders of magnitude lower, with distinctive surface perturbations. The amplitude and complexity of the perturbations increase as the normal velocity vector changes its direction and magnitude. These perturbations were recorded with a profilometer and analyzed using non-linear dynamical analysis tools. This study provides an opportunity to interpret surface phenomena of one of the most general cases of fracture and to study the effect of major variables on the nature of the perturbations involved, such as the local crack tip velocity and the crystallographic orientations. It is shown that the surface perturbations are chaotic deterministic in nature and can be described by high order non-linear differential equations; the order of the equation varying with the variations of the local velocity and direction.

Characterization of Crystalline Silicon via XRPD

Three blocks of silicon have been crashed in this experiment in order to verify the crashing effects on specimens having distinct original micro-structural arrangements. One of them comes from a rod bar of mono-crystal silicon, two others were from polycrystalline silicon manufactured by two distinct manufacturers with distinct growing process. Several specimens of powders, differing in type and grain size, were obtained by treating these source samples. This paper reports on data collected from synchrotron and conventional radiation and the results show that powders obtained from mono-crystalline silicon provide diffraction profiles, where the structural contribution is smaller than for polycrystalline silicon specimens. The peaks from the 'mono-crystal powder' resulted even narrower than peaks from SRM Silicon 640b by NIST.

Simulations of the electrostatic potential in a thin silicon specimen containing a p-n junction

ABSTRACTThe measurement of potentials associated with dopant atoms in semiconductors at nanometer spatial resolution using off-axis electron holography is known to be affected by the presence of the surfaces of thin specimens. In particular, the potential across a p-n junction is often found to be lower than would be expected from predicted properties of bulk devices. Here we present simulations of two-dimensional potential profiles within a thin (&lt;1 µm) parallel-sided specimen containing a p-n junction. We find that the potential across the p-n junction is always smaller, when projected through the specimen, than would be expected from the properties of the bulk material. Crucially, the step in potential across the junction is independent of the value of the potential on the surface of the specimen for high dopant concentrations (&gt;1017 cm−3). The simulations are compared with experimental data. Although they can account for some of the reduction in the observed potential, they do not fully explain the experimental results.

Oxidation study of Sb + implanted Si(1 0 0) and Si(1 1 1) targets. Use of high-resolution RBS technique

High-resolution Rutherford backscattering spectroscopy (RBS) was used to study the oxidation phenomenon of antimony-implanted silicon targets. The study was carried out with respect to antimony dose and silicon target orientation. The behavior of antimony ions before and after silicon oxidation was also investigated. Prior to the oxidation process, the Si(1 0 0) and Si(1 1 1) targets were implanted to 5×10 14 or 5×10 15 Sb +cm −2 dose, at 60 keV energy. The dry oxidation of the silicon specimens, was performed under oxygen atmosphere at 900°C for 30 min. The analysis was carried out by means of RBS technique in both random and channeling modes. A beam of H + particles was used for an energy of 0.3 MeV, with a detection resolution of 2 keV. It was shown that the oxidation phenomenon was more important on Si(1 1 1) targets than on Si(1 0 0). The SiO 2 oxide layer increased with the rise in antimony ions dose. Besides, after annealing under oxygen atmosphere, a good surface damage recovery was obtained for all implanted samples. An important quantity of antimony was found to be shadowed for the case of Si(1 0 0) targets which were implanted with 5×10 14 Sb +cm −2 dose. However, for the case of 5×10 15 Sb + cm −2 dose, no shadowing of antimony ions was observed.

Stress wave interference effects during fracture of silicon micromachined specimens

We report on unique measurements of multiple microsecond-duration arrest periods during the propagation of high speed (>1 km s−1) cracks in micromachined single-crystal silicon specimens. These events were recorded electronically and in physical features remaining on the fracture plane. Using time-of-flight calculations, we have determined that these arrest patterns are due to the interference of boundary-reflected stress waves with the propagating crack tip. The specimen size, the measurement method, and the low acoustic attenuation in cyrstalline silicon facilitated the observation of these phenomena.

Schottky diode back contacts for high frequency capacitance studies on semiconductors

A technique using large-area Schottky diode back contacts has been developed to enable high frequency capacitance studies to be carried out on semiconductors without the need to fabricate high quality ohmic back contacts. This technique will find application for very high resistivity materials or for the characterization of novel semiconductors when a method of producing good ohmic contacts has not been established. In this method a back contact much larger in area than the front contact diode under test is used. It is then found that accurate capacitance–voltage measurements can be made of the ionized doping density and, provided the back contact has sufficient leakage, the built-in potential can also be measured. Such specimens may also be used for characterization using the deep level transient spectroscopy (DLTS) technique and this is demonstrated by obtaining DLTS spectra from very high resistivity silicon specimens containing oxygen precipitates and comparing these to similar spectra obtained from more highly doped material.

Hydrogen Distribution in Carbon and Silicon Specimens Studied by the Scanning Atom Probe

Hydrogen Distribution in Carbon and Silicon Specimens Studied by the Scanning Atom Probe

Effect of oxygen partial pressure on silicon single crystal growth by floating zone technique: surface oxidation and Marangoni flow

AbstractSilicon single crystals were grown by the floating‐zone method using an infrared image furnace in the wide range of oxygen partial pressure defined at the inlet of the furnace from 1×10−2Pa to 8.2×102Pa (Po2surface = 5.3 × 10−24Pa to 3.6 × 10−14Pa), so that the Marangoni number was changed from 2070 to 616. Degree of surface oxidation of the grown crystal was dependent on oxygen partial pressure of an ambient atmosphere. Striation pattern in almost all crystal shows a single frequency. At Po2inlet = 4.9 × 102Pa (Po2surface = 1.3 × 10−14Pa: imaginary Marangoni number of 700) precipitation of SiO2 was observed at the melt surface. At Po2inlet = 8.2 × 102Pa (Po2surface = 3.6 × 10−14Pa: imaginary Marangoni number of 616), which is over the equilibrium oxygen partial pressure for a SiO2 phase, the silicon specimen was polycrystallized and showed no growth striation. Temperature coefficient of surface tension |‐∂σ/∂T| less than 0.25 × 10−3 N/m‐K is not realistic, although many small values have been reported.

Velocity dependent crack deflection in single crystal silicon

When a 〈0 0 1〉 single crystal silicon specimen is fractured under bending at low strain energy and velocity, it prefers to cleave along the vertical {1 1 0} plane. When the same specimen is fractured under the same conditions but at higher strain energy and velocity, it cleaves on the inclined {1 1 1} plane. We analyze this phenomenon, and suggest that the cause of this phenomenon is the anisotropic velocity dependent fracture energy.

829 X 線回折援用引張り試験装置の開発による MEMS 材料の機械的性質評価

This paper presents the development of tensile test technique for evaluation of elastic properties of MEMS materials in order to reliably design MEMS. A compact tensile tester operating in X-ray diffraction system was newly developed to measure Young's modulus, Poisson's ratio and fracture strength of micro-sized single/poly crystalline materials. Changes of X-ray diffraction patterns with increasing a tensile stress directly derived lateral strains of single crystal silicon (Si) specimens. Averaged value of Young's modulus and Poisson's ratio of the specimens was 168 GPa and 0.270,respectively, in agreement with analytical values calculated from anisotropic theory. This technique has, therefore, great potential for evaluating mechanical properties of micro-sized materials.

Development of In-Situ Surface Observation System with an Atomic Resolution under Tensile Stress by Atomic Force Microscope.

A new in-situ surface observation system under tensile stress with an atomic resolution has been developed for the purpose of the explanation of the deformation of the surface and the crack growth mechanism for thin films in the micro- and nano-mechanical systems. The mechanical properties such as Young's modulus can be determined at the same time. This observation system consists of the on-chip tensile testing system and a commercialized atomic force microscope (AFM). The on-chip testing system is characterized by a static loading mechanism with a flat spring and a test chip of single-crystal silicon of 15×15×0.5 mm. Particular attention has been paid to the suppression of the vibration which effects on images of the surface with an atomic resolution. Atomic images of the surface of mica can be observed under various tensile strains till the occurrence of the fracture. The growth of the cracks and Young's modulus for TiN thin film deposited on silicon (100) specimen can be also clarified.

Hackle or textured mirror? Analysis of surface perturbation in single crystal silicon

The fracture surfaces of strip-like single crystal silicon specimens, loaded statically under three-point bending to fracture, revealed an exceptional behavior of surface perturbations generated during the unstably propagating crack. The observed perturbations presented a unique opportunity to study and interpret the relationship between the local crack tip velocity and the mirror and the hackle mechanisms. We show that the high amplitude, more disturbed perturbations are generated at low local crack front velocity, and therefore can termed as a mirror, while the lower amplitude, relatively smooth perturbations are associated with the fastest local crack front velocity, which is actually a hackle mechanism, in contrast to the current knowledge of crack velocity and the associated mirror and hackle mechanisms.

Optical Spectra of Residual Porous Silicon

The spectra of absorption (μ), reflection (R), e2, and E 2e2 of residual silicon (r-Si) were calculated using the R spectra of porous silicon in the range from 0 to 20 eV and with e2(E) in the range 2.5–5.0 eV of porous silicon specimens with P = 0.57, 0.66, and 0.77. The e2 spectra of r-Si were decomposed into elemental components. We calculated their main parameters: the energies of maxima E i and halfwidths H i of bands, their areas S i , and heights I i , and oscillator strengths f i . The two-phase Bruggeman model of effective dielectric function and Kramers–Kronig analysis were applied in the calculations. The essential differences between the optical spectra of the residual and cubic silicon were established. They are at least partially attributed to the quantum dimensional effects. The data obtained are compared with the known theoretical spectra of silicon clusters.