A new approach for the simulation of dynamic electron backscatter diffraction (EBSD) patterns is introduced. The computational approach merges deterministic dynamic electron-scattering computations based on Bloch waves with a stochastic Monte Carlo (MC) simulation of the energy, depth, and directional distributions of the backscattered electrons (BSEs). An efficient numerical scheme is introduced, based on a modified Lambert projection, for the computation of the scintillator electron count as a function of the position and orientation of the EBSD detector; the approach allows for the rapid computation of an individual EBSD pattern by bi-linear interpolation of a master EBSD pattern. The master pattern stores the BSE yield as a function of the electron exit direction and exit energy and is used along with weight factors extracted from the MC simulation to obtain energy-weighted simulated EBSD patterns. Example simulations for nickel yield realistic patterns and energy-dependent trends in pattern blurring versus filter window energies are in agreement with experimental energy-filtered EBSD observations reported in the literature.

High performance III-V lasers at datacom and telecom wavelengths on on-axis (001) Si are needed for scalable datacenter interconnect technologies. We demonstrate electrically injected quantum dot lasers grown on on-axis (001) Si patterned with {111} v-grooves lying in the [110] direction. No additional Ge buffers or substrate miscut was used. The active region consists of five InAs/InGaAs dot-in-a-well layers. We achieve continuous wave lasing with thresholds as low as 36 mA and operation up to 80°C.

We report a systematic study of high quality GaAs growths on on-axis (001) GaP/Si substrates using molecular beam epitaxy. Various types of dislocation filter layers and growth temperatures of initial GaAs layer were investigated to reduce the threading dislocation densities in GaAs on GaP/Si. Electron channeling contrast imaging techniques revealed that an optimized GaAs buffer layer with thermal cycle annealing and InGaAs/GaAs dislocation filter layers has a threading dislocation density of 7.2 Â 10 6 cm À2 , which is a factor of 40 lower than an unoptimized GaAs buffer. The root-mean-square surface roughness was greatly decreased from 7.8 nm to 2.9 nm after the optimization process. A strong enhancement in photoluminescence intensity indicates that the optimized GaAs template grown on on-axis (001) GaP/Si substrates is a promising virtual substrate for Si-based optoelectronic devices.

In polycrystalline metallic materials, quantitative and statistical assessment of the plasticity in relation to the microstructure is necessary to understand the deformation processes during mechanical loading. Plastic deformation often localizes into physical slip bands at the sub-grain scale. Detrimental microstructural configurations that result in the formation and evolution of slip bands during loading require advanced strain mapping techniques for the identification of these atomically sharp discontinuities. A new discontinuity-tolerant DIC method, Heaviside-DIC, has been developed to account for discontinuities in the displacement field. Displacement fields have been measured at the scale of the physical slip bands over large areas in nickel-based superalloys by high resolution scanning electron microscopy digital image correlation (SEM DIC). However, conventional DIC methods cannot quantitatively measure plastic localization in the presence of discontinuous kinematic fields such as those produced by slip bands. The Heaviside-DIC technique can autonomously detect discontinuities, providing information about their location, inclination, and identify slip systems (in combination with orientation mapping). Using Heaviside-DIC, discontinuities are physically evaluated as sharp shear-localization events, allowing for the quantitative measure of strain amplitude nearby the discontinuities. Measurements using the new Heaviside-DIC technique are compared to conventional DIC methods for identical materials and imaging conditions.

We study experimentally spontaneous pattern formation in a dry dense granular medium invaded by an aqueous glycerin solution in a radial Hele-Shaw cell. By varying the invading fluid viscosity via the weight concentration of glycerin, and by adjusting the normalized injection velocity via the injection rate and the gap size of the cell, we observe four distinct fluid-grain displacement regimes: (i) a simple radial flow regime, (ii) an infiltration-dominated regime, (iii) a grain displacement-dominated regime, and (iv) a viscous fingering-dominated regime. We argue that these displacement regimes emerge as a result of competition among the various energy dissipation mechanisms and can be classified based on the characteristic times involved in the injection process.