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

Optical and field emission (FE) properties of aligned single-crystalline ZnO nanorods, grown on aluminium substrate at 530 degrees 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 E-2 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 5.8V mu m(-1) and the emission current density reached to 0.061 mA cm(-2) at an applied electrical field of 9.0V mu m(-1) and shows no saturation. The field enhancement factor beta was estimated, from the F-N plot, to be about similar to 2.081 x 10(3).