Growth of isotopically enriched ZnO nanorods of excellent optical quality

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 E2low and E2high phonon modes when the Zn isotope is changed from 64Zn to 68Zn, 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 line width) is excellent. Samples with Zn isotopic enrichment ranging from 64ZnO to 68ZnO 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 both the excellent optical quality and successful isotopic substitution of ZnO nanorods using this relatively simple growth method.