The preferential growth and related textural evolution during static recrystallization in a cold-rolled Mg-Zn-Gd alloy

The grain growth process plays an important role in the texture formation in magnesium alloys.The microstructural and micro-textural evolution of a cold-rolled Mg-Zn-Gd alloy during annealing at 350℃for 60-190 min were tracked by quasi-in-situ electron backscatter diffraction method.The results show that grain growth takes place gradually with the annealing time increasing.Moreover,the TD-split texture maintains the texture type but alters in three aspects-the increased tilting angle,the decreased pole intensity and the widened distribution of high-intensity area.Grains with their c-axis tilting 45-70°from normal direction show preferential growth which is closely associated with the texture changes.The original grain size advantage is one of the important factors leading to the growth advantage,some grain boundaries,such as 50-60°[1^(-)21^(-)0],50-60°[2750],60-70°[1^(-)21^(-)0](18b),and 70-80°[1^(-)01^(-)0](10)are also considered to be related to this preferential growth.

Controllable growth of GeSi nanostructures by molecular beam epitaxy

We present an overview on the recent progress achieved on the controllable growth of diverse GeSi al- loy nanostructures by molecular beam epitaxy. Prevailing theories for controlled growth of Ge nanostructures on patterned as well as inclined Si surfaces are outlined firstly, followed by reviews on the preferential growth of Ge nanoislands on patterned Si substrates, Ge nanowires and high density nanoislands grown on inclined Si surfaces, and the readily tunable Ge nanostructures on Si nanopillars. Ge nanostructures with controlled geometries, spatial distributions and densities, including two-dimensional ordered nanoislands, three-dimensional ordered quantum dot crystals, ordered nanorings, coupled quantum dot molecules, ordered nanowires and nanopillar alloys, are dis- cussed in detail. A single Ge quantum dot-photonic crystal microcavity coupled optical emission device demon- stration fabricated by using the preferentially grown Ge nanoisland technique is also introduced. Finally, we sum- marize the current technology status with a look at the future development trends and application challenges for controllable growth of Ge nanostructures.

Effects of Sn-doping on morphology and optical properties of CdTe polycrystalline films

Sn-doped CdTe polycrystalline films were successfully deposited on ITO glass substrates by close space sublimation. The effects of Sn-doping on the microstructure, surface morphology, and optical properties of polycrys- talline films were studied using X-ray diffraction, scanning electron microscopy, and ultraviolet-visible spectrophotometry, respectively. The results show that the lower molar ratio of Sn and CdTe conduces to a strongly preferential orientation of （111） in films and a larger grain size, which indicates that the crystallinity of films can be improved by appropriate Sn-doping. As the molar ratio of Sn and CdTe increases, the preferential orientation of （111） in films becomes weaker, the grain size becomes smaller, and the crystal boundary becomes indistinct, which indicates that the crystallization growth of films is incomplete. However, as the Sn content increases, optical absorption becomes stronger in the visible region. In summary, a strongly preferential orientation of （111） in films and a larger grain size can be obtained by appropriate Sn-doping （molar ratio of Sn ： CdTe = 0.06 ： 1）, while the film retains a relatively high optical absorption in the visible region. However, Sn-doping has no obvious influence on the energy gap of CdTe films.