Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userUltra-fast visualization of deformation mechanism for dynamically-compressed silicon
70
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Sub-picosecond x-ray diffraction was used to measure (100)-oriented silicon under laser-driven shock compression, providing an unambiguous atomistic picture of silicon phase transitions. We determine the orientation relationship between the Si-V and Si-I phases, and connect it with the specific deformation mechanism. We provide the first direct evidence of the inelastic deformation of Si under laser-driven shock compression, i.e., the shear stress is relieved by the phase transition without the occurrence of defect-mediated plasticity. We also demonstrate metastability of the high-pressure Si-II phase down to ambient pressure, which could lead to the synthesis of novel functional materials.
rate research
Read More
We reveal the microscopic self-diffusion process of compact tri-interstitials in silicon using a combination of molecular dynamics and nudged elastic band methods. We find that the compact tri-interstitial moves by a collective displacement, involving both translation and rotation, of five atoms in a screw-like motion along $[111]$ directions. The elucidation of this pathway demonstrates the utility of combining tight-binding molecular dynamics with textit{ab initio} density functional calculations to probe diffusion mechanisms. Using density functional theory to obtain diffusion barriers and the prefactor, we calculate a diffusion constant of $ 4 cdot 10^{-5} exp (- 0.49 {rm eV} / k_{B} T) {rm cm^2/s} $. Because of the low diffusion barrier, $I_{3}^{b}$ diffusion may be an important process under conditions such as ion implantation that creates excess interstitials, hence favoring formation of interstitial clusters.
The development of Low-Gain Avalanche Detectors has opened up the possibility of manufacturing silicon detectors with signal larger than that of traditional sensors. In this paper we explore the timing performance of Low-Gain Avalanche Detectors, and in particular we demonstrate the possibility of obtaining ultra-fast silicon detector with time resolution of less than 20 picosecond.
Strontium cobaltite (SrCoOx) is known as a material showing fast topotactic electrochemical Redox reaction so-called oxygen sponge. Although atomic scale phenomenon of the oxidation of SrCoO2.5 into SrCoO3 is known, the macroscopic phenomenon has not been clarified yet thus far. Here, we visualize the electrochemical oxidation of SrCoOx macroscopically. SrCoOx epitaxial films with various oxidation states were prepared by the electrochemical oxidation of SrCoO2.5 film into SrCoO3-d film. Steep decrease of both resistivity and the absolute value of thermopower of electrochemically oxidized SrCoOx epitaxial films indicated the columnar oxidation firstly occurred along with the surface normal and then spread in the perpendicular to the normal. Further, we directly visualized the phenomena using the conductive AFM. This macroscopic image of the electrochemical oxidation would be useful to develop a functional device utilizing the electrochemical redox reaction of SrCoOx.
The mass transfer of interstitial impurities in a crystalline lattice under the influence of the fast-moving deformation disturbance of the type of a shock wave is considered. The velocity of the movement of the disturbance is supposed to be compared with the characteristic velocity of the relaxation of the diffusion flux to its local equilibrium value determined by the Ficks law. The similar situation occurs in a number of experiments on the exposure of a solid to dynamical external loads giving rise to such fast hydrodynamical processes in a sample that the local equilibrium assumption, normally assumed for the macroscopic description of transport processes, is no longer valid. Considering the diffusion flux among the set of independent variables we have derived a set of coupled hydrodynamic equations describing nonequilibrium behavior of a solid in the absence of local equilibrium in the system. Within the scope of the proposed model it has been shown that in comparison with the local equilibrium system an enhanced mass transfer occurs under local nonequilibrium conditions.
The role of reduced dimensionality and of the surface on electron-phonon (e-ph) coupling in silicon nanowires is determined from first principles. Surface termination and chemistry is found to have a relatively small influence, whereas reduced dimensionality fundamentally alters the behavior of deformation potentials. As a consequence, electron coupling to breathing modes emerges that cannot be described by conventional treatments of e-ph coupling. The consequences for physical properties such as scattering lengths and mobilities are significant: the mobilities for [110] grown wires are 6 times larger than those for [100] wires, an effect that cannot be predicted without the form we find for Si nanowire deformation potentials.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
