Effect of Electron-Beam Irradiation on the Cathodoluminescence of a ZnO Nanorod Array

The effect of low-energy electron-beam irradiation on the cathodoluminescence of ZnO nanorods is studied. The nanorods are grown by gas-phase synthesis on oxidized silicon substrates at a temperature of about 550°C. It is shown that at the initial stage of irradiation the luminescence intensity increases and the rate of this process depends on the electron-beam current. Apparently, this is associated with chemical reactions on the sample surface stimulated by the electron beam. Annealing at 500°C leads to suppression of this effect. Thus, this effect cannot be explained only by the formation of a carbon-containing film upon irradiation. At high irradiation doses luminescence quenching is observed. The quenching rates are different for the initial and annealed samples. An “after-effect” is found. This manifests itself in a decrease in the luminescence intensity even after the beam is turned off.