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Optical properties of wurtzite ZnO bulk single crystals in which an arbitrary number (typically 109–1010 cm−2) of fresh dislocations were introduced intentionally by the plastic deformation at elevated temperatures (923–1073 K) were examined. Deformed specimens showed excitonic light emission with photon energies of 3.100 and 3.345 eV, as well as their LO phonon replicas at 11 K. The light intensities increased with increasing dislocation density. The activation energy for a thermal quenching of the 3.100 or 3.345 eV emission band, which corresponds to the depth of the localized energy level associated with the emission band, was estimated to be 0.3±0.1 or 0.05±0.01 eV, respectively. The origin of the energy levels was proposed as point defect complexes involving dislocations. The introduction of the dislocations at the elevated temperatures above 923 K did not influence the intensities of the emission bands except the dislocation-related emission bands.

A novel flower-shaped Bi 2 O 3 superstructure has been successfully synthesized by calcination of the precursor, which was prepared via a citric acid assisted hydrothermal process. The precursor and Bi 2 O 3 were characterized with respect to morphology, crystal structure and elemental chemical state by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was shown that both the precursor and Bi 2 O 3 flower-shaped superstructure were constructed of numerous nanosheets while the nanosheets consisted of a great deal of nanoparticles.Furthermore, key factors for the formation of the superstructures have been proposed; a mechanism for the growth of the superstructure has been presented based on the FESEM investigation of different growth stages.

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The dynamic behavior of dislocations in highly boron (B)-doped Si crystals with concentration up to 2.5×1020 cm−3 is investigated using the etch pit technique. Suppression of the generation of dislocations from a surface scratch is found for B-doped Si and the critical stress for dislocation generation increases with B concentration, which is interpreted in terms of dislocation locking due to impurity segregation. The velocity of dislocations in B-doped crystals is revealed to increase by increasing the B concentration.

This article will report the epitaxial growth of high-quality p-type ZnO layers on Zn-face ZnO substrates by nitrogen and tellurium (N+Te) codoping. ZnO:[N+Te] films show p-type conductivity with a hole concentration of 4 Â 10 16 cm À3 , while ZnO:N shows n-type conduction. The photoluminescence of ZnO:N shows broad bound exciton emission lines. Meanwhile, ZnO:[N+Te] layers show dominant A 0 X emission line at 3.359 eV, with a linewidth as narrow as 1.2 meV. Its X-ray linewidth shows narrower line width of 30 arcsec. Detailed investigation of photoluminescence properties of (N+Te) codoped ZnO layers suggest that the binding energy of N acceptors lies in a range of 121-157 meV. #

Extended defects acting as non‐radiative recombination center or those acting as radiative one were, respectively, studied by transmission electron microscopy under the illumination of a monochromatic light or cathodoluminescence spectroscopy combined with light illumination. By means of this method, defect levels associated with dislocations in ZnO, which were introduced at elevated temperatures above 923 K, were determined. It was proposed that (i) a screw dislocation, presumably acting as non‐radiative recombination center, glides under the illumination of a light with photon energy above 2.48–2.61 eV, due to an electron–hole recombination at a defect level of 2.48–2.61 eV depth, and (ii) a mixed dislocation acts as radiative recombination center with a defect level of 3.1 eV depth.