Role of defects in modulating the near band edge emissions of sub-micron ZnO crystals

Abstract

Abstract In this communication, we identify the role of defects in modulating the optical properties of ZnO sub-micron rod and tube structures by measuring and comparing their temperature dependent (18 K–260 K) photoluminescence (PL) behavior. From statistical fitting of the near band edge (NBE) emission region of the spectra, it is observed that the acceptor exciton (A, X) emissions decrease with an increase in temperature for ZnO rod structures, whereas comparatively less variation is recorded for ZnO tubular structures. Employing various mathematical analyses, the emission patterns observed for tubular structures are concluded to arise from their lattice dilation and the electron-phonon interactions. For the rod structures, however, it is concluded that the emission spectra are primarily due to the defects (i.e. oxygen and/or Zn vacancies) present at their polar faces. The defects present at the ZnO basal plane affecting (A, X) emissions will influence the use of ZnO in optoelectronic applications.