ZnO nanoparticles were fabricated in sapphire (α-Al(2)O(3) single crystal) by Zn ion implantation (48 keV) at an ion fluence of 1 × 10(17) cm(-2) and subsequent thermal annealing in a flowing oxygen atmosphere. Transmission electron microscopy (TEM) analysis revealed that metallic Zn nanoparticles of 3-10 nm in dimensions formed in the as-implanted sample and that ZnO nanoparticles of 10-12 nm in dimensions formed after annealing at 600 °C. A broad absorption band, peaked at 280 nm, appeared in the as-implanted crystal, due to surface plasma resonance (SPR) absorption of metallic Zn nanoparticles. After annealing at 600 °C, ZnO nanoparticles resulted in an exciton absorption peak at 360 nm. The photoluminescence (PL) of the as-implanted sample was very weak when using a He-Cd 325 nm line as the excitation source. However, two emission peaks appeared in the PL spectrum of ZnO nanopraticles, i.e., one ultraviolet (UV) peak at 370 nm and the other a green peak at 500 nm. The emission at 500 nm is stronger and has potential applications in green/blue light-emitting devices.

Novel phosphorus-doped and undoped single crystal ZnO nanotetrapods were fabricated on sapphire by a simple chemical vapour deposition method, using phosphorus pentoxide (P2O5) as the dopant source. The optical properties of the samples were investigated by photoluminescence (PL) spectroscopy. Low-temperature PL measurements of phosphorus-doped and undoped samples were compared, and the results indicated a decrease in deep level defects due to the incorporation of a phosphorus acceptor dopant. The PL spectrum of the phosphorus-doped sample at 10 K exhibited several acceptor-bound exciton related emission peaks. The effect of phosphorus doping on the optical characteristics of the samples was investigated by excitation intensity and temperature dependent PL spectra. The acceptor-binding energies of the phosphorus dopant were estimated to be about 120 meV, in good agreement with the corresponding theoretical and experimental values in phosphorus-doped ZnO films and nanowires.

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Ultralong ZnO piezoelectric‐fine‐wires (PFWs) with a perfect hexagonal structure have been prepared by an upstream growing chemical vapor deposition (CVD) method. Furthermore, isolatable and flexible piezoelectric strain sensors based on individual ZnO PFWs have been fabricated by a simple and reliable technique. The whole device was fully packaged by epoxy polymeric resin (EPR). The I–V characteristic of the isolatable sensor is highly sensitive to the strain applied on it, which was well interpreted in terms of variation in Schottky barrier height (SBH) caused by strain induced band structure change and piezoelectric effect. The sensor exhibited excellent stability and fine reversibility, and a remarkably high gauge factor up to 1010 had been achieved. It is expected that the isolatable and flexible piezoelectric strain sensor demonstrated here will have applications in detection of external mechanical forces, as well as electromechanical switch with a high ON/OFF ratio.

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