Optical and field emission properties of single-crystalline aligned ZnO nanorods grown on aluminium substrate

Abstract

Optical and field emission (FE) properties of aligned single-crystalline ZnO nanorods, grown on aluminium substrate at 530 °C by the non-catalytic thermal evaporation process, have been examined. Raman-scattering and room-temperature PL spectra exhibit a strong and sharp optical phonon E2 mode at 437 cm−1 and a strong ultraviolet emission at 381 nm, respectively. The FE characterization shows that a turn-on field for the vertically aligned nanorods was 5.8 V µm−1 and the emission current density reached to 0.061 mA cm−2 at an applied electrical field of 9.0 V µm−1 and shows no saturation. The field enhancement factor β was estimated, from the F–N plot, to be about ∼2.081 × 103.