ABSTRACT
Figure 2.1 presents the SEM image of the sample. From the SEM image, it is seen that the ZnO nanorods are vertically aligned with the diameter of about 100 nm and the length of about 2 µm. Figure 2.2 (a) plots the TIPL spectrum of the ZnO nanorods measured at 4.3 K. An emission band at 3.355 eV with a full width at half maximum (FWHM) of 13.6 meV is observed. The ZnO layer deposited with sputtering is polycrystalline and showed very weak luminescence before the fabrication of ZnO nanorods. However, the luminescence is significantly enhanced after the deposition of the ZnO nanorods. Therefore the luminescence we measured is mainly from the ZnO nanorods. Since the PL spectrum was measured with the excitation
of high-intensity fs pulses, the PL spectrum is dominated by radiative recombination of free excitons. The defects-related green band is not detectable, showing the high quality of the sample.
