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Optical and electrical properties of fresh dislocations in GaN bulk crystals deformed plastically at elevated temperatures were reviewed. A dislocation band model was proposed. The fresh dislocations of ( a /3) [ 1 2 ¯ 10 ] -type edge dislocations on the ( 10 1 ¯ 0 ) prismatic plane induced several photoluminescence peaks at around 1.8, 1.9 and 2.4 eV, which implies the formation of radiative recombination centers of the dislocations. Simultaneously, near-band-edge (3.48 eV) photoluminescence intensity decreased remarkably for a high-density of non-radiative recombination centers originating in deformation-induced abundant Ga-vacancy related clusters. The intensity variation of yellow luminescence with plastic deformation and subsequent annealing did not relate to the native property of dislocations. Variation of optical absorption dependent on the strain in plastically deformed GaN was understood in a model of the Franz–Keldysh effect by the electric fields associated with charged dislocations (~5.8 e/nm). Scanning spreading resistance microscopic images showed many spots with high conductivity around the induced dislocations, showing electrical conduction along dislocations according to the Frenkel–Poole mechanism. [ABSTRACT FROM AUTHOR]

Heavily tin (Sn)-doped Si crystals in a concentration up to 4×1019 cm−3 were grown by the Czochralski method. Variation of Sn concentration in the crystals was well expressed by the Pfann equation using a segregation coefficient of k=0.016. From the occurrence of growth interface instability and the appearance of Sn precipitates in the grown crystals, the solubility limit of Sn was considered to be around 5×1019 cm−3. Interstitially dissolved oxygen Oi was presented at a concentration of 8–9×1017 cm−3 in the grown Sn-doped crystals. The FT-IR absorption peak relating to a Si–Oi–Si quasi-molecule at 1106cm−1 showed preferential occupation of Oi at the bond-centered position of Si–Si. The Oi peak shifted to the lower wave number side with increasing Sn concentration in Si, implying expansion of the Si–Si bond. [ABSTRACT FROM AUTHOR]

Abstract: Si-rich Si x Ge1 −x alloys (0.93

Abstract: Czochralski growth of bulk crystals of Si x Ge1− x alloys and their fundamental properties were reported. Full single crystals of large size, larger than 25mm in diameter and longer than 40mm in length, were obtained for the alloys of composition and . Single crystals of SiGe alloys heavily doped with electrically active impurities with a concentration up to 1020 cm−3 were also successfully obtained. The velocity for single crystal growth in the whole composition range was evaluated and discussed in terms of the occurrence of the constitutional supercooling. The study on the local atomic structure shows that most of the strain in SiGe alloys is accommodated by changes of both the bond length and bond angle. Electrical and thermal conductivities show the minima at the intermediate composition at , implying the alloy scattering due to a distortion of the crystal lattice. Oxygen impurities, incorporating from a quartz crucible, occupy preferentially a bond-center site between Si atoms to make an Si–O–Si quasi-molecule. The mechanical strength of the alloys becomes temperature insensitive at elevated temperatures and depends on the composition, being proportional to x(1–x) over the whole composition range, which may be originating in the built-in stress fields related to microscopic fluctuation of alloy composition and the dynamic interaction between dislocations and solute atoms. [Copyright &y& Elsevier]

We investigated the local atomic structure in GeSi alloy experimentally and theoretically. Extended X-ray absorption fine structure measurements in Czochralski-grown Ge1−xSix bulk alloys showed that the Ge&z.sbnd;Ge and Ge&z.sbnd;Si bond lengths maintain distinctly different lengths and vary linearly with alloy composition across the whole composition range 0. This is in good agreement with the expectation derived from ab initio electronic structure calculations. The result indicates that the bond lengths and bond angles are distorted with alloy composition in GeSi. [Copyright &y& Elsevier]

The yield strength of GaN bulk crystals determined directly by means of compressive deformation is around 100–200 MPa in the temperature range 900–1000°C. On the basis of the observed temperature and strain rate dependencies of yield stress, the dislocation mobility at elevated temperatures is evaluated. Deformed GaN shows a drastic reduction of PL intensity, suggesting that newly formed dislocations give rise to non-radiative recombination centers. [Copyright &y& Elsevier]

The dynamic interaction between dislocations and impurities B, P and Ge in Si with concentrations up to 2.5×1020 cm−3 is investigated by the etch-pit technique, in comparison with that of O impurity in Si. Dislocation generation from a surface scratch is strongly suppressed when the concentration of B and P impurities exceeds 1×1019 cm−3, originating from the immobilization by preferential impurity segregation. Dislocation velocity in motion enhances on increasing the concentration in B and P impurities. Neutral impurity Ge has weak effect on dislocation generation and velocity enhancement. [Copyright &y& Elsevier]

The electron spin resonance spectra Si-B3 and NL51 were detected in hydrogen-doped float-zone-grown silicon (Si) samples after electron-irradiation and annealing for the first time. Recently, the Si-B3 spectra were attributed to tetra-self-interstitial (I4) agglomerates in positive charge-state, however an origin of the NL51 spectra was not yet established. Results obtained in this study suggest that the NL51 originate from an excitonic state of neutral I4 agglomerate in Si. Therefore, detection of interstitial agglomerates in Si at early stages of their formation becomes possible. [Copyright &y& Elsevier]

Highlights: [•] We form an intense micro- and near-field light probe for conventional thin specimens under TEM, by which both structural and optical properties are obtained in-situ, with a high energy resolution simultaneously with a high spatial resolution. [•] The light probes can be applied to in-situ TEM of the structural variation of nanostructures via photo-excitation, as well as photoluminescence (PL) and Raman spectroscopies. [•] The light probes will be applied to determine photo-excitation effects of optoelectronic materials successively from a microscopic level to a nanoscopic one. [Copyright &y& Elsevier]

Abstract: Dynamic interaction between dislocations and impurities in Si is investigated by using X-ray topography and the etch-pit technique from the viewpoint of Czochralski growth of Si crystals. Dislocation generation is effectively suppressed by doping of B and co-doping of B and Ge, which is originating in the immobilization of dislocations by preferential segregation of impurities. Dislocation velocity in motion is enhanced by increasing the concentration in B impurities. Change of the lattice parameter due to the impurity doping leads to the generation of misfit dislocations at the seed/crystal interface. [Copyright &y& Elsevier]