Investigating the source of deep-level photoluminescence in ZnO nanorods using optically detected x-ray absorption spectroscopy

Abstract

A zinc oxide (ZnO) nanorod array exhibiting an intense deep-level emission (DLE) was probed at the Zn K edge (9659 eV) using extended x-ray absorption fine structure (EXAFS) analysis. X-ray excited optical luminescence was used to obtain site-specific information around the absorbing Zn atom using optically detected EXAFS (ODXAS). The visible-emission corresponds to defects in ZnO crystal lattice introduced during growth. A comparative study between red (660 nm) and green (500 nm) DLE was conducted by collecting specific wavelength emissions of the optically detected x-ray absorption spectra. It was shown that red emission primarily originates from the nanorod surface, and green emission was linked to disorder occurring on Zn sites. We show that ODXAS can distinguish between two emission regions and provides a platform to link defect emission with specific crystal structures. © 2013 AIP Publishing LLC.