Optical properties of indium doped ZnO planar superlattice nanoribbons

Abstract The indium-doped zinc-oxide (IZO) planar superlattice nanoribbons were synthesized by a chemical vapor transport method. The x-ray diffraction pattern and high resolution transmission electron microscopy image indicate that the synthesized nanoribbons have planar superlattice structures formulated as In 2 O 3 ( ZnO ) m with small m ( m = 3 , 5 ). The Photoluminescence (PL) spectrum of the planar superlattice nanoribbons (NRs) shows only one dominant broad asymmetric excitonic emission with a peak at 3.371 eV, which is about 14 meV higher than the bound exciton emission in pure ZnO. The PL blueshift observed in NRs was attributed to the quantum confinement effect due to small thickness of the In/Zn-O slab. From the temperature dependence of the PL intensity, the activation energy of donor bound exciton bound to In donors in IZO was derived to be around 18.3–25.7 meV. We also obtained the shrinkage parameters of the band gap of the NRs, α = 1.0 − 1.2 meV / K and β = 500 − 520 K , by using the Varshni empirical formula.