We demonstrate that highly porous ZnO nanobelts can be prepared by thermally decomposing ZnS(en)_0.5 hybrid nanobelts (NBs) synthesized through a solvothermal route using Zn layers deposited on alumina substrates as both the Zn substrate and source. Hybrid decomposition by thermal annealing at 400 °C gives porous ZnS NBs that are transformed by further annealing at 600 °C into wurtzite single crystal ZnO nanobelts with an axial direction of [0001]. The evolution of the morphological and structural transformation ZnS(en)_0.5 → ZnS → ZnO is investigated at the nanoscale by transmission and scanning electron microscopy analyses. Control of the ZnO NB distributions by patterning the Zn metallization on alumina is achieved as a consequence of the parent hybrid NB patterned growth. The presence of NBs on alumina in a 100 μm wide region between Zn stripes allows us to fabricate two contact devices where contact pads are electrically connected through a porous ZnO NB entanglement. Such devices are suitable for employment in photodetectors as well as in gas and humidity sensors.

The synthesis of ZnO porous nanobelts with high surface-to-volume ratio is envisaged to enhance the zinc oxide sensing and photocatalytic properties. Yet, controlled stoichiometry, doping and compensation of as-grown n-type behavior remain open problems for this compound. Here, we demonstrate the effect of residual sulfur atoms on the optical properties of ZnO highly porous, albeit purely wurtzite, nanobelts synthesized by solvothermal decomposition of ZnS hybrids. By means of combined cathodoluminescence analyses and density functional theory calculations, we attribute a feature appearing at 2.36 eV in the optical emission spectra to sulfur related intra-gap states. A comparison of different sulfur configurations in the ZnO matrix demonstrates the complex compensating effect on the electronic properties of the system induced by S-inclusion.

Previous studies have shown that the electrical activation of a given implanted Al concentration in 4H-SiC increases with the increasing of the post implantation annealing temperature up to 1950–2100°C and different annealing times in the range 0.5–5 min. This study shows that, at 1950°C, the electrical activation of Al implanted in 4H-SiC increases with the increase of the annealing time up to attain saturation for annealing times longer than 22 min. Samples were obtained from the same Al implanted HPSI 4H-SiC wafer with an implanted Al concentration lower than the Al solubility limit in 4H-SiC at the annealing temperature of 1950°C. The annealing time was varied in the range 5–40 min.