Optical properties of ZnO-alloyed nanocrystalline films

Abstract

ZnO is emerging as one of the materials of choice for UV applications. It has a deep excitonic energy level and a direct bandgap of ~3.4eV. Alloying ZnO with certain atomic constituents adds new optical and electronic functionalities to ZnO. This paper presents research on M g x Z n 1 - x O and Z n S 1 - x O x nanocrystalline flexible films, which enable tunable optical properties in the deep-UV and in the visible range. The ZnO and Mg 0.3 Zn 0.7 O films were found to have bandgaps at 3.35 and 4.02eV, respectively. The photoluminescence of the Mg 0.3 Zn 0.7 O exhibited a bandedge emission at 3.95eV, and at lower energy 3.38eV due to the limited solubility inherent to these alloys. ZnS 0.76 O 0.24 and ZnS 0.16 O 0.84 were found to have bandgaps at 3.21 and 2.65eV, respectively. The effect of nitrogen doping on ZnS 0.16 O 0.84 is discussed in terms of the highly lattice mismatched nature of these alloys and the resulting valence-band modification. Copyright © 2012 Hui Che et al.