Photoluminescence and Raman Studies of Annealed ZnO Nanostructures

2012 ◽  
Vol 501 ◽  
pp. 179-183 ◽  
Author(s):  
Siti Khadijah Mohd Bakhori ◽  
Chuo Ann Ling ◽  
Shahrom Mahmud
Keyword(s):  
Optical Signal ◽  
High Mode ◽  
Raman Shift ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Zno Nanostructures ◽  
Zno Nanostructure ◽  
Band Emission ◽  
Crystallite Sizes ◽  
Tem Microscopy

The influence of annealing on the optical properties of as-grown ZnO nanostructures prepared in pellets has been investigated by photoluminescence (PL) and Raman spectroscopy. The annealing temperatures of ZnO nanostructure at 600°C, 650°C and 700 °C were conducted in oxygen (O2) and nitrogen (N2) ambient. The near band edge emission (NBE) of samples recorded in the PL spectra demonstrates significant changes on optical signal whereby the NBE is redshifted after O2 annealed and became slightly higher in N2 annealed. Apart from that, weak green luminescence (GL) namely deep band emission (DBE) is observed centre at 532.95 nm (2.23 eV) and 511.00 nm (2.42 eV) for annealed in O2 and N2 respectively, whereas lower DBE observed in as-grown ZnO. On the other hand, Raman shift reveal the phonon mode of the ZnO nanostructures and the E2 (high) mode were downshifted as annealed in O2 ambient, and upshifted in N2 ambient. The downshift and upshift of the E2 (high) mode are correlated to tensile and compressive stress. Moreover the crystallite sizes were calculated from FWHM of XRD and TEM microscopy reveals the nanoplates structure of ZnO nanostructures.

Effects of Annealing Treatment on Structural, Optical and Morphology Characteristics of ZnO Nanostructures

2012 ◽  
Vol 626 ◽  
pp. 967-970 ◽  
Author(s):  
Siti Khadijah Mohd Bakhori ◽  
Chuo Ann Ling ◽  
Shahrom Mahmud
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Annealing Treatment ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Zno Nanostructures ◽  
Zno Nanostructure ◽  
Band Emission ◽  
Transmission Electron ◽  
Xrd Patterns

The ZnO nanostructure produced by CFCO or French process were undergone annealing treatment at 700°C in oxygen and nitrogen ambient. Subsequently, the characteristics of structural, optical and morphology of ZnO nanostructures were investigated using X-ray diffraction (XRD), photoluminescence (PL) and transmission electron microscopy (TEM) respectively. The crystallite size of the nanostructures were calculated from full width half maximum (FWHM) of (101) peak in XRD patterns and the size is around 42 nm. PL measuremment were carried out and the near band edge emission (NBE) is increase in wavelength or namely redshifted. Moreover, deep band emission (DBE) is observed at 520 nm for ZnO annealed in nitrogen, which commonly regarded as the defect level of oxygen vacancies. The investigation continues with conducting transmission electron microscopy (TEM) to demonstrate the mophology of as grown nanostructures and annealed in both nitrogen and oxygen ambient.

MORPHOLOGICAL AND PHYSICAL PROPERTIES OF ZnO NANOSTRUCTURES GROWN ON Sb-DOPED ZnO SEEDING FILMS ANNEALED UNDER DIFFERENT ATMOSPHERES

2021 ◽  
pp. 2150116
Author(s):  
WUTTICHAI SINORNATE ◽  
HIDENORI MIMURA ◽  
WISANU PECHARAPA
Keyword(s):  
Physical Properties ◽  
Sol Gel ◽  
Hydrothermal Process ◽  
Visible Region ◽  
High Growth ◽  
High Growth Rate ◽  
Near Band Edge ◽  
Zno Nanostructures ◽  
Zno Nanostructure ◽  
Doped Zno

In this work, morphological and physical properties of pyramid-like ZnO nanostructures fabricated on Sb-doped ZnO seeding films annealed under different atmospheres are extensively studied. The Sb-doped ZnO seeding films were first prepared by sol–gel spin coating technique onto glass substrate then annealed in nitrogen, air and argon followed by low-temperature hydrothermal process for ZnO nanostructures fabrication. The morphological results exhibit the growth of pyramid-like ZnO nanostructure with increasing density of the ZnO nanostructures. The crystal structure shows pyramid-like ZnO wurtzite hexagonal growth along the c-axis without any impurity phase. The growth of pyramid-like ZnO nanostructures is due to the high growth rate of (002) plane. Photoluminescence spectra exhibit the near-band-edge of all samples while the red emission appears in ZnO nanostructures after the hydrothermal process due to the imperfection in the crystal. The reflectance of ZnO nanostructures covers the visible region with the absorption edge of 375[Formula: see text]nm. The calculation shows the relevant energy band gaps in the range of 3.26–3.28[Formula: see text]eV. The difference in hydrothermally grown ZnO nanostructures is significantly affected by different annealing atmospheres.

Growth Spindle-Like ZnO Nanocrystalline Thin Films on Nickel Layers by Dc Magnetron Sputtering and its Thermal Annealing Properties

2011 ◽  
Vol 675-677 ◽  
pp. 1097-1100
Author(s):  
W. Wu ◽  
X.H. Xiao ◽  
T.C. Peng ◽  
C.Z. Jiang
Keyword(s):  
Thin Film ◽  
Magnetron Sputtering ◽  
Structural Features ◽  
Optical Quality ◽  
Zno Films ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Dc Magnetron Sputtering ◽  
Band Emission ◽  
Thin Film Layer

A novel spindle-like zinc oxide (ZnO) nanocrystalline thin film was successfully fabricated on Ni thin film layer by ultrahigh-vacuum dc magnetron sputtering. Then the as-grown films were annealed in air at various temperatures from 673 to 1073 K, the corresponding structural features and surface morphology were studied by X-ray diffraction (XRD) and field emission scanning electronic microscopy (FE-SEM). The results reveal that the dominant direction of grains movement changed from perpendicular to parallel to the film interfaces. A correlation of the band gap and photoluminescence (PL) properties of nanocrystalline ZnO films with particle size morphologies and strain was discussed. Especially, PL emission in UV range, which is due to near band edge emission is more intense in comparison with the green band emission (due to defect state) was observed in all samples, indicating a good optical quality of the deposited films.

Hydrothermal Synthesis of Flower-Like ZnO Nanostructures and their Optical Properties

2013 ◽  
Vol 678 ◽  
pp. 91-96
Author(s):  
Krishnan Sambath ◽  
Manickam Saroja ◽  
Muthusamy Venkatachalam ◽  
Krishnan Rajendran ◽  
Kumaravelu Jagatheeswaran
Keyword(s):  
Visible Region ◽  
Blue Emission ◽  
Hexagonal Wurtzite Structure ◽  
Zinc Nitrate ◽  
Near Band Edge ◽  
Nitrate Hexahydrate ◽  
Zno Nanostructures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Band Emission

Flower-like ZnO nanostructures have been synthesized using zinc nitrate hexahydrate and hexamethylenetetramine (HMT) by a low-temperature hydrothermal technique. The prepared ZnO nanostructures exhibit hexagonal wurtzite structure, well-defined flower-like morphology, and a strong blue emission photoluminescence. Flower-like ZnO nanostructures consisting of multilayered petals are formed with the length of about 1 μm. All the flower petals exhibit the tapering feature with the root size of 300-500 nm and tip size of 50-100 nm. The prepared ZnO sample has been studied using x-ray diffraction technique, energy dispersive x-ray analysis, scanning electron microscope and FTIR spectroscopy. The photoluminescence spectrum demonstrated two emission bands, a near band edge (NBE) emission in the UV region centering at 386 nm and a high intensity deep band emission (DBE) in the visible region centering at 483 nm.

RAPID THERMAL ANNEALING INDUCED ENHANCED BAND-EDGE EMISSION FROM ZnO NANOWIRES, NANORODS AND NANORIBBONS

2011 ◽  
Vol 04 (01) ◽  
pp. 25-29 ◽  
Author(s):  
SOUMEN DHARA ◽  
P. K. GIRI
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Green Emission ◽  
Spectral Shift ◽  
Zno Nanowires ◽  
Band Edge ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Zno Nanostructures ◽  
Time Resolved

In this letter, we report on the enhanced near band edge (NBE) photoluminescence (PL) emission by rapid thermal annealing (RTA) of ZnO nanowires, nanoribbons and nanorods synthesized by vapor transport method using a ZnO nanopowder source. As a result of RTA, the intensity ratio of NBE to green emission peak is nearly doubled for the nanowires, while this enhancement is one order of magnitude for the nanoribbons and nanorods. Time-resolved PL studies on the green emission band shows a single-exponential decay (time constant ~ns) after RTA. The Raman spectral shift of the RTA treated samples indicates reduced tensile strain in the annealed ZnO nanostructures. Our results demonstrate the effectiveness of RTA process for improving the crystallinity and optical properties of ZnO nanostructures.

Visible Luminescence from ZnO Nanostructures

2006 ◽  
Vol 957 ◽  
Author(s):  
An-jen Cheng ◽  
Dake Wang ◽  
Hee Won Seo ◽  
Minseo Park ◽  
Yonhua Tzeng
Keyword(s):  
Gas Flow ◽  
Blue Emission ◽  
Chemical Vapor ◽  
Ultra Violet ◽  
Reaction Chamber ◽  
Near Band Edge ◽  
Zno Nanostructures ◽  
Green Band ◽  
Band Emission ◽  
Visible Luminescence

ABSTRACTRoom temperature photoluminescence (PL) spectra from zinc oxide (ZnO) nanostructures were studied. ZnO samples were produced via thermal chemical vapor deposition (thermal-CVD) and a variety of ZnO nanostructures were synthesized by adjusting the oxygen content during the growth process. All samples exhibit a sharp and strong ultra-violet near-band-edge (NBE) emission at about 3.18 eV. The visible emission from the samples deposited under an oxygen-deficient condition were dominated by blue-green band emission at 2.34 eV. The intensity of the blue-green band was greatly reduced (so-called green band free) for the ZnO deposited at the center of the wafer while strong violet-blue emission bands and broad bands at yellow-orange-red range were collected from the ZnO grown along the edge of the wafer. We believe that the spatial inhomogeniety was caused by turbulent gas flow in the reaction chamber, which resulted in different local oxygen concentration. Origin of visible luminescence from ZnO nanostructures will be discussed and a model to explain the observed visible luminescence process will be presented.

Self-Assembled ZnO Nanostructure for Field-Emission Devices

2009 ◽  
Vol 4 ◽  
pp. 19-25 ◽  
Author(s):  
P. Bhattacharya ◽  
D. Varshney ◽  
K. Samanta ◽  
R.S. Katiyar
Keyword(s):  
Field Emission ◽  
Self Assembly ◽  
Zno Nanorods ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Xrd Pattern ◽  
Field Emission Properties ◽  
Zno Nanostructure ◽  
Si Substrates ◽  
Transport Method

Zinc oxide (ZnO) nanorods on Au patterned Si substrates were fabricated using vapor transport method. The XRD pattern showed the ZnO nanorods were highly c-axis oriented similar to ZnO thin films. The photoluminescence spectrum at 77 K of ZnO nanorods was consisting of the fundamental near band edge emission of ZnO in the UV region along with a broad defect induced emission around green band. The field emission properties of the nanorods showed a current density of 1mA/cm2 at an applied field of 10V/m, which is comparable to other reported values of ZnO nanorods. The patterned gold island formed by self-assembly of polystyrene ball on Si substrate acted as a catalyst in the growth of nanorods as well as stable ohmic contact for field emission.

Anomalous luminescent properties in ZnO and SrAl2O4 composites

RSC Advances ◽  
2014 ◽  
Vol 4 (69) ◽  
pp. 36765-36770
Author(s):  
V. P. Singh ◽  
P. Mohanty ◽  
S. P. Lochab ◽  
Chandana Rath
Keyword(s):  
Monoclinic Phase ◽  
Hexagonal Phase ◽  
Energy Band Diagram ◽  
Luminescent Properties ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Band Diagram ◽  
Edge Emission ◽  
Defect Band ◽  
Band Emission

We showed a phase transformation from high temperature hexagonal phase to most stable monoclinic phase of SrAl2O4 by incorporating 20% of ZnO in ZnO and SrAl2O4 composite (Singh et al. 2014 Dalton Transactions). The composite with monoclinic phase further showed the intense near band edge emission and defect band emission corresponding to ZnO without any signature of SrAl2O4 in PL spectra. An energy band diagram responsible for defect band emission is proposed for the composites.

Investigation of the Optical Properties of CdZnTe by IR Transmission and PL Spectra

2005 ◽  
Vol 475-479 ◽  
pp. 1841-1844 ◽  
Author(s):  
Guo Qiang Li ◽  
Wan Qi Jie
Keyword(s):  
Optical Properties ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Transmission Spectra ◽  
Pl Spectra ◽  
Band Emission ◽  
Ir Transmission ◽  
Vertical Bridgman ◽  
Donor Acceptor ◽  
Transmission Measurements

The optical properties of CdZnTe crystals grown by vertical Bridgman method were investigated in detail by infrared (IR) transmission spectra and photoluminescence (PL) spectra. IR transmission measurements showed that according to the trends of the IR transmission with the wavenumbers, IR transmission spectra could be classified into four types, i.e. descending, ascending, low straight and high straight. Each of them indicated one type of CdZnTe crystals with specified properties. PL measurements revealed that the low-temperature PL spectra consisted of three emissions: the near-band-edge emission (I0) situated at 1.66eV related to the free and bound excitons, the donor-acceptor emission (I1) centered at 1.62eV related to the impurities, and a defect band emission (I2) centered at 1.50eV due to the dislocations. The full width at half maximum (FWHM) of I0 and the PL intensity ratios of I1/I0 and I2/I0 could be used to evaluate the properties of the crystals.

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