Photoluminescence Of ZnO Nanostructures Research Articles

Effect of Ag doping on the microstructure and photoluminescence of ZnO nanostructures

ZnO nanostructures were obtained by metal-organic chemical vapor deposition via Ag catalyst-assisted growth in a temperature range of 200–500 °C. Growth at temperatures above 500 °C resulted in vertically aligned ZnO nanorods (NLs). Ag incorporation into ZnO up to 0.4 at.% promoted creation of basal plane stacking fault (BSF) defects and corrugation of the side facets of the NLs. The presence of BSFs give rise to an additional photoluminescence peak with a wavelength of ∼386 nm, which is slightly red-shifted compared to the commonly observed NBE emission at ∼375 nm. The observed emission was found to be specifically observed from the side facets of the NLs. It is suggested that this emission is due to a high concentration of BSFs in the ZnO as a result of an incorporation of Ag as acceptor dopant. SEM image of an Ag-doped ZnO nanorod with corrugated side facets. The observed corrugation is accompanied by a high concentration of basal plane stacking faults.

Control on the Photoluminescence of ZnO Nanostructures Synthesized by a Reverse Micellar Route

ZnO nanostructures with controlable properties were synthesized by a reverse micellar system. The morphology and photoluminescence of ZnO nanostructures can be controlled by changing the the ratio of reaction Zn(NO3)2 and MEA. As the ratio of MEA/ Zn(NO3)2 is low, ZnO nanodots were generated with strong blue emission; as the ratio of MEA/ Zn(NO3)2 is increased, the formation of ZnO nanorods with green emission were synthesized. Since the photoluminescence (PL) properties could be adjusted by varying the nanostructures, these ZnO materials have high potential on different applications, for instance, as fluorescence probes.

Frabrication and Photoluminesence of ZnO Nanobelt with Superlength Nanocantilevers

ZnO nanobelts with ultralong nanocantilevers were synthesized by evaporating ZnO powders. The nanobelts have an average width of 200nm and thickness of 50nm. It grows along the direction, with±(2110) and±(0001)side surfaces. The growth direction of the nanocantilevers is along [0001], perpendicular to the (0001) side surface of the nanobelts and they have ultralong length, even to tens of micrometers. The growth mechanism and dynamics of the nanostructures are proposed. The surface polarization as an important factor for formed the growth of nanocantilevers. Because of the ultra-long nanocantilevers, this structure could be potentially useful as nanocantilever arrays for nanosensors and nanotweezers. The room-temperature photoluminescence of ZnO nanostructures is discussed.

The effect of morphology and doping on photoluminescence of ZnO nanostructures

In this work, optical properties of ZnO nanostructures prepared by chemical vapor deposition under different conditions were investigated. ZnO nanostructures were characterized by electron microscopy and photoluminescence. A high intensity green emission and a narrow UV emission band are observed in photoluminescence spectra of ZnO nanostructures related to the below-band-gap and band-edge that their intensities depend on the morphology of the nanostructures. It is considered that the green emission is originated from structural defects. In addition, the influence of thermal treatment and dopants such as iron and copper, on the photoluminescence (PL) properties of the ZnO nanostructures was investigated.

Low-temperature synthesis and photoluminescence of ZnO nanostructures by a facile hydrothermal process

We reported a facile route to large-scale ZnO nanostructures by a poly (styrene- alt-maleic acid sodium) (PSMA)-assisted hydrothermal process. Various nanostructures including nanowires, nanobelts and nanorod arrays were fabricated depending on the experimental conditions. The structural studies reveal that all the nanostructures are single crystal with hexagonal phase and preferentially grow along [0 0 0 1]. The organic additive PSMA offers a spatial template for the one-dimensional (1D) growth of ZnO. The photoluminescence (PL) spectra of these nanostructures exhibit coexistence properties of ultraviolet (UV) and green emission. The nanorod arrays and nanobelts exhibit the strongest UV performance and green emission, respectively. We deduce that quantity of surface defects should be responsible for the difference in PL properties of these nanostructures.

Non-Resonant Two-Photon Absorption-Induced Photoluminescence Study on ZnO Nanostructures Epitaxially Grown on Si (100) Substrates by Chemical Vapor Deposition Method

AbstractWe report on experimental results of non-resonant two-photon absorption-induced photoluminescence in ZnO nanostructures, which may act as a possible route to excite ZnO nanostructure based lasers. Epitaxial ZnO nanorod-like nanostructure was grown on pre-seeded Si (100) substrates by chemical vapor deposition (CVD) method with a mixed ZnO/C solid source. Crystalline ZnO seeds were prepared and controlled by the rapid thermal annealing (RTA) treatment of e-beam deposited amorphous ZnO thin films with various thicknesses.

Effect of Variable Pressure on Growth and Photoluminescence of ZnO Nanostructures

Thin films constituted of equiaxed and one dimensional nanostructures of ZnO via metal-catalyst-free vapor phase were grown using a simplistic thermal evaporation technique under two different pressure conditions approximately of the order of 10(-1) and 10(-3) torr, respectively. ZnO deposited at low vacuum (approximately 10(-1) torr) exhibited the formation of nanograins of variable size between 60 to 180 nm. In contrast the film grown at high vacuum (approximately 10(-3) torr) resulted the nanowired type morphology with a random networking, generally distributed with equiaxed grains of film microstructure. The diameter of maximum number of these nanowires lies between 45 to 65 nm. The films grown at low vacuum has shown almost equal composition of Zn and O while the film grown at high vacuum has shown lower content of O. The nanowires formed under limited O (high vacuum: approximately 10(-3) torr) signifies the role of O vacancies during growth. It has been postulated that presumably under high vacuum deposition, initially formed ZnO transforms to ZnOx (x < 1) through creation of O vacancies due to limited presence of O. Subsequently ZnOx acts as self-catalyst and heterogeneous nuclei are responsible for the formation of nanowired type morphology. The effect of different microstructures has been correlated and discussed to understand the photoluminescence characteristics obtained on these films.

Silver Nanoisland Induced Synthesis of ZnO Nanostructures by Vapor Phase Transport

ZnO nanostructures including nanorod and nanotower were synthesized on Ag nanoisland coated Si substrate by thermal evaporation and vapor phase transport at atmospheric pressure. The as-prepared ZnO nanorods and nanotowers were single crystal growing along [0001] direction. The growth of ZnO nanostructures strongly depended on the surface morphology of the nanoisland Ag film deposited by electroless nanoelectrochemistry. The growth mechanism of the ZnO nanostructures was proposed on the basis of experimental data. A strong room-temperature photoluminescence in ZnO nanostructures has been demonstrated. The growth technique would be of particular interest for direct integration in the current silicon-technology-based optoelectronic devices.

Synthesis of ZnO nanostructures on CuO catalyzed porous silicon substrate

Mass production of ZnO nanobelts, cuboid nanorods, and hexagonal nanorods has been successfully synthesized on CuO catalyzed porous silicon (PS) using the simple vapor–solid (VS) growth method. Deionized water is a critical experimental parameter for the synthesis of different morphology of ZnO nanostructures. A comparison of their morphologies was investigated by scanning electron microscopy (SEM). Transmission electron microscopy (TEM) confirmed that ZnO nanobelts and nanorods are single crystalline with the growth direction of (0110) and (0001), respectively. A strong room-temperature photoluminescence in ZnO nanostructures has been demonstrated.

Preparation and photoluminescence of ZnO nanostructures by thermal evaporation growth without catalysts

ZnO nanostructures have been grown on p-type Si(1 0 0) and glass substrates by thermal evaporating pure zinc powder without any metal catalysts at 450 or 480 °C. The microstructures of the samples under SEM show nanowires, nanorods and feathers-like morphologies. XRD reveals a preferred orientation of the well-aligned nanorods grown on silicon substrates at 480 °C. And all kinds of grown nanostructural samples are hexagonal ZnO crystal. The growth mechanism of synthesized nanostructures is discussed. Temperature and substrate are critical experimental parameters for the formation of different morphologies of ZnO nanostructures. Room-temperature photoluminescence spectrum of the well-aligned nanorods shows a blue emission band at 420 and 444 nm. The blue luminescence is due to the electrons transition from the shallow donor levels of oxygen vacancies to the valence band.

Formation of ZnO nanostructures by a simple way of thermal evaporation

Mass production of ZnO nanowires, nanoribbons, and needle-like rods has been achieved by a simple method of thermal evaporation of ZnO powders mixed with graphite. Metallic catalysts, carrying gases, and vacuum conditions are not necessary. Temperature is the critical experimental parameter for the formation of different morphologies of ZnO nanostructures. Zn or Zn suboxide plays a crucial role for the nucleation of ZnO nanostructures. The as-prepared ZnO nanowires consist of single crystalline cores and thin amorphous shells. As determined by electron diffraction, the growth direction of ZnO nanowires is [001], which has no orientation relationship with the substrate. A strong room-temperature photoluminescence in ZnO nanostructures has been demonstrated.