One-dimensional ZnO nanostructures (nanowires/nanorods) are attractive materials for applications such as gas sensors, biosensors, solar cells, and photocatalysts. This is due to the relatively easy production process of these kinds of nanostructures with excellent charge carrier transport properties and high crystalline quality. In this work, we review the photoluminescence (PL) properties of single and collective ZnO nanowires and nanorods. As different growth techniques were obtained for the presented samples, a brief review of two popular growth methods, vapor-liquid-solid (VLS) and hydrothermal, is shown. Then, a discussion of the emission process and characteristics of the near-band edge excitonic emission (NBE) and deep-level emission (DLE) bands is presented. Their respective contribution to the total emission of the nanostructure is discussed using the spatial information distribution obtained by scanning transmission electron microscopy−cathodoluminescence (STEM-CL) measurements. Also, the influence of surface effects on the photoluminescence of ZnO nanowires, as well as the temperature dependence, is briefly discussed for both ultraviolet and visible emissions. Finally, we present a discussion of the size reduction effects of the two main photoluminescent bands of ZnO. For a wide emission (near ultra-violet and visible), which has sometimes been attributed to different origins, we present a summary of the different native point defects or trap centers in ZnO as a cause for the different deep-level emission bands.
Strong white and blue photoluminescence (PL) from as-grown silicon nanocrystals (nc-Si) in
SiNx
films prepared by remote plasma enhanced chemical vapour deposition using
SiCl4/NH3
mixtures is reported. The colour and intensity of the PL could be controlled by adjusting the
NH3
flow rate. Samples with white emission were annealed at
1000 °C, obtaining a strong improvement of the PL intensity with a blue colour. The
PL can be attributed to quantum confinement effect in nc-Si embedded in
SiNx
matrix, which is improved when a better passivation of nc-Si surface with chlorine and
nitrogen atoms is obtained. The size, density and structure of the nc-Si in the as-grown and
annealed films were confirmed and measured by high-resolution transmission electron
microscopy.
Articles you may be interested inDistinguishing the effect of surface passivation from the effect of size on the photonic and electronic behavior of porous siliconWe have investigated the influence of the microstructure and chemistry of the surrounding host on the strong visible photoluminescence ͑PL͒ from silicon nanoclusters ͑nc-Si͒ embedded in three different silicon-based dielectric compounds: Si x N y : H , Cl, Si x N y O z : H , Cl, and Si x O z :H,Cl, obtained from silicon nitride films deposited by SiH 2 Cl 2 /NH 3 /H 2 plasma-enhanced chemical vapor deposition at different growth pressures. A blueshift is found in the PL coming from the nc-Si as the content of oxygen in the surrounding host is increased, and a significant improvement in PL intensity is achieved when the nc-Si are well passivated with O instead of H. We discuss the PL behavior in terms of the quantum confinement model and passivation state of the nc-Si surface.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.