Field emission properties of indium-doped ZnO tetrapods

Indium-doped ZnO (ZnO:In) tetrapods (TPs) with considerably high In content (In < 15 at.%) have been successfully synthesized by a mixed-source vapor phase transportation method (VPT). Powder X-ray diffraction (XRD) measurement of ZnO:In TPs revealed a single hexagonal phase, that indicates high structural quality of ZnO:In TPs. From room-temperature photoluminescence (PL) spectra, the Burstein-Moss (BM) shift was observed, which shows an increase of extrinsic carrier concentration. Also, we could observe field emission from ZnO:In TPs (8 at.%) with a threshold voltage (Eth) of 5.36 V/μm at a current density of 0.1 μA/cm2. These results show the feasibility of impurity doping for tailoring the physical properties of ZnO-based nanostructures.