Room Temperature Strong Emission and Excitonic Enhancement in Multiple‐Stacked Nano‐Porous ZnO Thin Film

Abstract

Electronic and structural properties of ZnO films before and after H 2 annealing treatment are studied. The initial system is smooth amorphous ZnO films that are intentionally grown at room temperature. A dramatic change is found in the crystallinity and the surface transforms to a multiple-stacked nanoporous structure upon annealing as observed by scanning electron microscopy and X-ray diffraction. Photoluminescence spectroscopy shows the presence of a new mid-gap state below the first optical transition, and the annealing treatment transforms the ZnO system to more transparent film. Interestingly, it is found that the structural evolution changes the dielectric function measured by high-resolution, angle-dependent spectroscopic ellipsometry and this generates strong emission at %2.5 eV. These results show the importance of structural modification via H 2 annealing to control the optical properties and electronic structure of ZnO films.

Tuning Optoelectronic Properties Through In‐Plane Arrangement and Point Defects in ZnO Nanorods as Prepared by Room‐Temperature DC‐Unbalanced Magnetron Sputtering

“…PL spectra of ZnO nanorods are dominated by green emission, which is centered at 2.42 eV. This emission is likely originated from the oxygen vacancy ( V O ), which is easily formed due to the deposition process carried out at room temperature and without the oxygen supply . The high amount of V O in the nanorods sample is due to a high surface‐to‐volume ratio.…”