Spatially resolved investigations of the emission around 3.31 eV (A-line) from ZnO nanocrystals

Abstract

ZnO nanocrystals grown by chemical solution deposition were studied by means of photoluminescence and cathodoluminescence spectroscopy. A postgrown annealing treatment significantly improved the UV emission efficiency and resulted in the clear appearance of a low temperature emission band around 3.31 eV (so-called A-line). Spatially and wavelength resolved cathodoluminescence measurements revealed a spotlike distribution of the A-line emission on a nanocrystal surface. It is found that there is a strong correlation between the emission around 3.31 eV and the specklike defects on the nanocrystal surface that appeared after annealing. The origin of the A-line and the specklike defects are discussed.

Nature of red luminescence in oxygen treated hydrothermally grown zinc oxide nanorods

“…In addition at 15 K the NBE blue shifts revealing a structured UV emission at 3.31 eV. This peak has been attributed to acceptors in ZnO involved in both donor-acceptor pairs and free-to-bound acceptor transitions as well as to excitons bound to surface or extended structural defects [28,29].…”

Shape controlled Sn doped ZnO nanostructures for tunable optical emission and transport properties

“…We have assigned this emission due to excitons bound to defect states (SX). 23,24 The peaks at 3.238 eV, 3.166 eV, and 3.094 eV are close to the integral multiple of longitudinal optical (LO) phonon replica (72 meV) 25 of SX, and attributed to SX-1LO, SX-2LO, and SX-3LO, respectively. For Sn doped samples, another peak is observed at 3.355 eV, which is also attributed to excitons bound to neutral donors, i.e.…”

Multicolor Luminescence from Semiconductor Nanocrystal Composites Tunable in an Electric Field

“…Wavelength resolved CL images as well as, spatially resolved CL spectra from ZnO nanocrystals show a direct correlation between the A-line emission at 3.311 eV and the annealing induced specklike defects (Kurbanov et al, 2009a). The specklike defects appear on all faces of the annealed nanocrystals and lead to a spotlike distribution of the emission.…”

“…The inset shows the specklike defects revealed after annealing at higher magnification. (Kurbanov, et al, 2009a) As-prepared ZnO nanocrystals display a strong UV luminescence accompanied with a weak yellow-orange emission at around 565 nm. With increasing the excitation power a violet PL band at ~400 nm starts to appear and it dominates over the UV near-band-gap emission at high excitation power.…”