Ultraviolet lasing and time-resolved photoluminescence of well-aligned ZnO nanorod arrays

Well-aligned ZnO nanorod arrays were synthesized by thermal evaporation of ZnO powder on ZnO thin films. The nanorods are almost the same length of 5.5 mu m and well-oriented perpendicular to the substrates. The time-integrated and time-resolved photoluminescence spectra of the nanorod arrays revealed the existence of laser action with the excitation threshold of 130 mu J/cm(2) and emission lifetime of less than 30 ps. At the excitation fluence a little below threshold, the decay fits well to a biexponential function with a fast component (similar to 80 ps) and a slower component (similar to 360 ps). (c) 2005 American Institute of Physics.