Radii Of Si Research Articles

Age hardening of Al-7Si-0.5Mg alloy: Role of Si size and distribution

The age-hardening behavior of the Al-7Si-0.5Mg alloy with different size and distribution of Si phase was investigated. The wedge-shaped mold was used to prepare specimens with different characteristics of Si. The specimen with fine and homogeneous Si showed accelerated age-hardening kinetics and higher peak hardness than the one with coarse and clustered Si due to the higher dislocation density resulted from the mismatch in the thermal contraction of Si and Al. The overlapping of the plastically-affected zone of the adjacent Si phase in the specimen with large and clustered Si led to a reduced volume fraction of the plastically-affected zone, lower dislocation density and lower age-hardening kinetics. The relationship between the radius of Si and the critical inter-particle spacing that minimize the interaction of adjacent Si to maximize the dislocation density and accelerate age-hardening kinetics was established.

High-resolution X-ray Bragg diffraction in Al thermomigrated Si channels

Si(111) wafers patterned with an array of vertical 120 µm-wide Al-doped (1 × 1019 cm−3) p-channels extending through the whole wafer were studied with the X-ray double- and triple-crystal diffraction technique in Bragg geometry with copper radiation. Reciprocal space maps (RSMs) of diffraction intensity far from the channels and near them were measured, and their non-trivial shape was observed. The obtained experimental RSMs demonstrate high sensitivity to the structural distortions of the crystal in the subsurface layer owing to the influence of the surface on the elastic strain field in the channel. These features result from the small difference of the ionic radii of Si and Al, leading to the absence of misfit dislocations on the borders of the channel. Simulations of RSMs using the Takagi–Taupin dynamical diffraction theory taking into account the influence of the surface on the elastic strain field in the channel and the effect of the instrumental function were carried out. Finally, numerical RSM calculations showed that the proposed model of the surface effect on the elastic strain field in a semi-infinite crystal with a vertical Si(Al) channel can be used to retrieve the information on the concentration of aluminium in the thermomigrated Si(Al) channel from the diffraction data obtained in the Bragg geometry.

Tunable and multi-channel perfect absorber based on graphene at mid-infrared region

A tunable, multi-channel plasmonic perfect absorber based on graphene is proposed. Simulated results reveal that the resonant wavelength can be effectively tuned in many ways (by changing the Fermi energy of graphene, radius of Si, or air gap between the Si and the graphene film). Furthermore, the multi-channel perfect absorber is obtained by changing the period of the system. Specifically, a high absorption is obtained by using a multilayer Bragg mirror in place of the metallic plate. We believe that such an absorber may have potential applications for multi-channel photodetectors, frequency selection, and electromagnetic-wave energy storage.

Analysis of DC and analog/RF performance on Cyl-GAA-TFET using distinct device geometry**Project supported by the Council of Scientific and Industrial Research (CSIR) Funded Research Project, Grant No. 22/0651/14/EMR-II, Government of India.

In this paper, analysis of DC and analog/RF performance on cylindrical gate-all-around tunnel field-effect transistor (TFET) has been made using distinct device geometry. Firstly, performance parameters of GAA-TFET are analyzed in terms of drain current, gate capacitances, transconductance, source-drain conductance at different radii and channel length. Furthermore, we also produce the geometrical analysis towards the optimized investigation of radio frequency parameters like cut-off frequency, maximum oscillation frequency and gain bandwidth product using a 3D technology computer-aided design ATLAS. Due to band-to-band tunneling based current mechanism unlike MOSFET, gate-bias dependence values as primary parameters of TFET differ. We also analyze that the maximum current occurs when radii of Si is around 8 nm due to high gate controllability over channel with reduced fringing effects and also there is no change in the current of TFET on varying its length from 100 to 40 nm. However current starts to increase when channel length is further reduced for 40 to 30 nm. Both of these trades-offs affect the RF performance of the device.

Bond lengths in the ternary compounds Ti3SiC2, Ti3GeC2 and Ti2GeC

The interatomic distances in the ternary compounds Ti3SiC2, Ti3GeC2 and Ti2GeC have been determined precisely by comparing the lattice parameters of Ti3GeC2 and Ti2GeC, on the one hand, and Ti3GeC2 and Ti3SiC2, on the other. The assumptions made were that the Ti–Ge and Ti–C distances in the Ge-containing phases were identical, and that the differences in the Ti–Si and Ti–Ge distances in Ti3SiC2 and Ti3GeC2 phases were equal to the differences in the covalent radii of Si and Ge. While the results clearly show that the TiC octahedra in the ternary phases are distorted, the extent of that distortion is smaller than previously reported. The extent of the distortion was found to depend on the type of atoms surrounding the TiC6 octahedrons; the deformation is larger in the Ge-containing than in the Si-containing compounds. However, the Ti–C–Ti distances appear to be insensitive to the nature of the compound.

Impurity and concentration dependence of growth rate during solid epitaxy of implanted Si

The increase of the growth rate during solid-phase epitaxy in silicon implanted with B, P, As, and Sb is explained in terms of strain in the host lattice due to the addition of the dopant. The growth rate increases proportionally to the strain thus taking into account both species and concentration dependence below the solid solubility limit. The strain itself is in a simple way related to the difference between the tetrahedral covalent radii of Si and of the dopant.

Variation of mean SiO bond lengths in silicon-oxygen octahedra

The mean bond length SiO in silicon-oxygen octahedra is a function of the mean coordination number of the oxygen atoms ( CN) in the octahedron: (SiO) mean = 1.729 + 0.013 CN. The radius of Si in six coordination against oxygen is 0.407 Å.