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The results of photoluminescence (PL) measurements performed on high quality single crystal ZnO implanted with radioactive 73 Ga and 73 As, both of which decay to stable 73 Ge, are presented. Identical effects are observed in the two cases, with a sharp line at 3.3225(5) eV found to grow in intensity in accordance with the growth rate of the Ge daughter atom populations. On the strength of the well-established result that Ga occupies Zn sites, we conclude from the identical outcomes for 73 Ga and 73 As implantations that implanted As also preferentially occupies Zn sites. This result supports the findings of others that As preferentially occupies the Zn rather than the O site in ZnO. The thermal quenching energy of the 3.3225(5) eV line is found to be only 2.9(1) meV in contrast to its large spectral shift of 53.4(1) meV with respect to the lowest energy free exciton. The PL is attributed to exciton recombination at neutral Ge double donors on Zn sites involving transitions that leave the donor in an excited state.

In this work we present a method for the deposition of periodically ordered, c-axis aligned ZnO nanorod arrays. By using chemical bath deposited films in conjunction with silica templating through nanosphere monolayers, masks suitable for high temperature deposition are created. A vapour phase transport technique is then used to deposit ordered arrays, quickly and inexpensively in a manner ideal for low cost, scalable and reproducible growth on a diverse range of substrates.

We have produced isotopically enriched ZnO nanorods using Zn-enriched ZnO source powder by vapour phase transport on silicon substrates buffer-coated with unenriched ZnO seed layers. SEM and XRD data confirm successful growth of high quality, dense, c-axis aligned nanorods over a substantial surface area. Raman data show a shift of >1 cm -1 in the peak position of the Raman scattered peaks due to the E 2 low and E 2 high phonon modes when the Zn isotope is changed from 64 Zn to 68 Zn, consistent with previous work, thus confirming successful isotopic enrichment. SIMS data provides additional confirmation of enrichment.The optical quality (as determined by photoluminescence feature intensity and linewidth) is excellent. Samples with Zn isotopic enrichment ranging from 64 ZnO to 68 ZnO display a shift in recombination energy of the bound excitons at the band edge (3.34 -3.37 eV) of ~ 0.6 meV. This blue shift is also consistent with previously published data, further confirming *Manuscript Revised Click here to view linked References 2 both the excellent optical quality and successful isotopic substitution of ZnO nanorods using this relatively simple growth method.

Undoped and Ni-doped ZnO micro-rod arrays were successfully synthesized by the spray pyrolysis method on glass substrates. Analysis of the samples with x-ray diffraction and scanning electron microscopy showed that these micro-rod arrays had a polycrystalline wurtzite structure with a highly c-axis preferred orientation. Photoluminescence studies at both 300 K and 10 K show that the incorporation of nickel leads to a relative increase in the visible blue light band intensity. Magnetic measurements indicated that Ni-doped ZnO samples exhibit ferromagnetic behavior at room temperature, which is possibly related to the presence of point defects.