Growth of 18 O isotopically enriched ZnO nanorods by two novel VPT methods

Abstract

We have developed two novel vapour phase transport methods to grow ZnO nanorod arrays isotopically enriched with 18 O. Firstly, a three-step process used to grow natural and Zn-enriched ZnO nanorods has been further modified, by replacing the atmospheric O 2 with enriched 18 O 2 , in order to grow 18 O-enriched ZnO nanorods using this vapour-solid method on chemical bath deposited buffer layers. In addition, 18 O-enriched ZnO nanorods were successfully grown using isotopically 18 O-enriched ZnO source powders in a vapour-liquidsolid growth method. Scanning electron microscopy studies confirmed the success of both growth methods in terms of nanorod morphology, although in the case of the vapour-liquidsolid samples, the nanorods' c-axes were not vertically aligned due to the use of a non

Local atomic environment of the Cu-related defect in zinc oxide

“…The detailed growth methods employed are described in references [38,39]. In short, the Zn-isotopically enriched samples were grown using a three-step process involving a dropcoated seed layer, and buffer layer of ZnO nanorods grown by chemical bath deposition (CBD) and finally isotopically enriched ZnO nanorods grown by carbothermal reduction vapour phase transport (CTR-VPT) using Zn-enriched source powders.…”

“…Oxygen-isotopically enriched ZnO nanorods were grown by two methods as previously reported. [39] The CTR-VPT growth process is based on the reduction of ZnO powder by the graphite to produce Zn vapour and carbon monoxide (CO). The Zn vapour is then re-oxidised in a vapour-solid (VS) process at the energetically favourable sites provided by the aligned CBD buffer layer using residual O 2 present in the tube during growth (rather than the O initially in the ZnO powder, which is captured by C to form CO).…”

“…Three samples were produced using this method: natural Zn 16 O by evacuating the tube and re-filling with 16 18 O enrichments, albeit substantial, differ from the nominal values by a considerable amount due to a variety of unanticipated sources of 16 O contamination and the actual enrichments are given in table 2 below. Details are given in reference [39].…”

“…The furnace then cooled overnight before the samples were removed. Three samples were produced with this method: Zn 16 18 O enrichments, albeit substantial, differ from the nominal values by a considerable amount due to a variety of unanticipated sources of 16 [38,39]. Zn 18 O, which is not seen for the NBE BX-lines.…”

“…the studies left open whether a complex of Cu Zn with other defects along the c-axis, for We have recently reported the growth of isotopically enriched ZnO nanorods grown using three novel methods. [38,39] Here, we report a combined optical study of both Zn-and O-isotopically enriched ZnO nanorods whose very high structural and optical quality allows detailed study of their optical properties at low temperatures concerning shallow and deep defect emission centres. Specifically, the near band edge (NBE) and the Cu-related SGB 2.86 eV ZPL data for such enriched ZnO materials are investigated and the effects of enrichment on the Cu-related defect at 2.86 eV is examined to further determine the local environment of the defect responsible.…”