Synthesis and field emission properties of ZnCdO hollow micro–nano spheres

The ZnCdO hollow micro–nano spheres have been achieved on the Si substrates without any catalysts using a simple thermal evaporation method. X-ray diffraction spectra confirm that the sample is a hexagonal wurtzite structure, and a little Cd doping would not change the crystal structures of ZnO. The growth mechanism of the ZnCdO hollow micro–nano spheres is deduced in detail. The PL spectra illustrate that Cd doping could induce the red-shift of optical band gap. Field emission measurements show a low turn-on field of ∼1.86V/μm at a current density of 1μA/cm2. The emission current density reached 1mA/cm2 at an applied field of ∼9.26V/μm.