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It is generally known that dry etching induces surface damage, but the structure of etched surfaces has not been studied in detail. Nor has it been established how or whether a clean, ordered surface can be recovered after etching damage. Generally, etching damages the surface by introducing structural disorder and impurities to the surface region. Such damage may be so severe that a clean, ordered surface is not recoverable even after heating up to ∼1400 K in UHV. We subjected Si (1 1 1) surfaces to different reactive ion etching conditions and/or post-etch treatments and examined their effect on the surface. Low temperature STM revealed that a clean, ordered surface as evidenced by the appearance of large area 7 × 7 reconstructions can be obtained only under certain etching/post-etch recipes. On the other hand, LEED showing 7 × 7 diffraction spots but with high intensity background and Auger electron spectroscopy (AES) showing no impurity signal cannot be used as evidence that an ordered surface has been obtained. © 2013 Elsevier B.V. All rights reserved.

Absolute external quantum efficiencies (eta s) and photoluminescence (PL) decay lifetimes of ZnO tetrapods grown at different temperatures were measured. All the tetrapods had an UV peak at about 390nm and a very weak defect emission. Measurements showed that the tetrapods have eta s of 2%-4% at room temperature. The sample, grown at optimal temperature, exhibited the largest absolute eta of 4.3% and longest PL decay lifetimes among all the samples. These results showed that precise control of growth temperature plays an important role in making high quality ZnO tetrapods. In time-resolved measurement, the PL decay time constant (tau) versus temperature is well fitted by the theoretical prediction tau = aT(3/2). This increase in PL lifetime with increasing temperature shows that the excited state relaxation is dominated by radiative recombination. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4737785]

ZnO nanorods were fabricated by electrodeposition from solution with and without thulium precursors and characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, photoluminescence and time-resolved photoluminescence. In spite of the low incorporation of thulium into ZnO nanorods, both the morphology and the optical properties of the nanorods were affected by the presence of thulium. The light emitting diodes with ZnO nanorods with and without Tm have been demonstrated. (C) 2010 Elsevier B.V. All rights reserved.