Emission Diversity of ZnO Nanocrystals with Different Growth Temperatures

2014 ◽  
Vol 1675 ◽  
pp. 45-51
Author(s):  
E. Velázquez Lozada ◽  
T. Torchynska ◽  
G. Camacho González
Keyword(s):  
Free Exciton ◽  
Ultrasonic Spray Pyrolysis ◽  
Second Order ◽  
Zno Films ◽  
Near Band Edge ◽  
Phonon Replica ◽  
Ultrasonic Spray ◽  
Zno Nanocrystals ◽  
Order Diffraction ◽  
Different Temperatures

ABSTRACTScanning electronic microscopy (SEM), X ray diffraction (XRD) and photoluminescence (PL) have been applied to the study of structural and optical properties of ZnO nanocrystals prepared by the ultrasonic spray pyrolysis (USP) at different temperatures. The variation of temperatures and times at the growth of ZnO films permits modifying the ZnO phase from the amorphous to crystalline, to change the size of ZnO nanocrystals (NCs), as well as to vary their photoluminescence spectra. The study has revealed three types of PL bands in ZnO NCs: defect related emission, the near-band-edge (NBE) PL, related to the LO phonon replica of free exciton (FE) recombination, and its second-order diffraction peaks. The PL bands, related to the LO phonon replica of FE, and its second-order diffraction in the room temperature Pl spectrum testify on the high quality of ZnO films prepared by the USP technology.

Transmittance, Absorbance and Emission of Ga related Defects in Ga-doped ZnO Nanocrystal Films

MRS Advances ◽  
2020 ◽  
Vol 5 (59-60) ◽  
pp. 3015-3022
Author(s):  
Tetyana V. Torchynska ◽  
Brahim El Filali ◽  
Jose L. Casas Espinola ◽  
Chetzyl I. Ballardo Rodriguez ◽  
Georgiy Polupan ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Emission Band ◽  
Free Exciton ◽  
Thermal Quenching ◽  
Ultrasonic Spray Pyrolysis ◽  
Optical Transmittance ◽  
Optical Bandgap ◽  
Zno Films ◽  
Near Band Edge ◽  
Phonon Replica

ZnO films grown by ultrasonic spray pyrolysis with different Ga contents in the range of 1.0-6.5 at% on quartz substrates have been studied. The ZnO:Ga films were annealed at 400°C for 4h in a nitrogen flow. Morphology, emission, transmittance, absorbance and electrical resistivity were controlled. It is revealed that with a small content of Ga ≤ 4.0 at%, the ZnO:Ga films maintain a flat morphology, their transmittance increases to 86% together with the increase of the ZnO optical bandgap to 3.28 eV and the intensity enlargement of the near band edge (NBE) emission band A (3.188 eV). Furthermore, the new NBE emission band B (3.072 eV) appears in photoluminescence (PL) spectra at Ga contents ≥ 1.5 at%. Simultaneously, the process of decreasing electrical resistivity becomes saturating. The last effect is attributed to the self-compensation effect in n-type ZnO:Ga films related to the generation of acceptor type complexes (VZn2- - GaZn+). The thermal quenching of the PL intensities of the A and B PL bands is studded at 18-290K, which allows assigning the PL band A to the LO-phonon replica of the free exciton emission and the band B to the emission in donor-acceptor pairs: shallow donors - acceptor complexes (VZn2- - GaZn+). The NBE emission intensity drops and the ZnO optical bandgap demonstrates the shift to a lower energy at Ga doping up to ≤ 6.5 at%. Optimal Ga concentrations have been estimated to produce ZnO:Ga films with flat morphology, high optical transmittance and bright NBE emission.

Photoluminescence Variation With Temperature in ZnO:Ag Nanorods obtained by Ultrasonic Spray Pyrolysis

2013 ◽  
Vol 1617 ◽  
pp. 113-117
Author(s):  
E. Velázquez Lozada ◽  
S. Mera Luna ◽  
L. Castañeda
Keyword(s):  
Spray Pyrolysis ◽  
Ultrasonic Spray Pyrolysis ◽  
Second Order ◽  
Band Edge ◽  
Near Band Edge ◽  
Pl Spectra ◽  
Ultrasonic Spray ◽  
Order Diffraction ◽  
Temperature Dependences ◽  
Ir Emission

ABSTRACTThe photoluminescence, its temperature dependences, as well as structural characteristics obtained by the method of Scanning electronic microscopy (SEM) have been studied in ZnO:Ag nanorods prepared by the ultrasonic spray pyrolysis (USP). PL spectra of ZnO:Ag NRs in the temperature range from 10 K to 300 K are investigated. Three types of PL bands have been revealed: i) the near-band-edge (NBE) emission, ii) defect related emission and iii) IR emission. It is shown that IR emission corresponds to the second-order diffraction of near-band-edge (NBE) emission bands. The study of NBE PL temperature dependences reveals that the acceptor bound exciton (ABE) and its second-order diffraction peak disappeared at the temperature higher than 200 K. The attenuation of the ABE peak intensity is ascribed to the thermal dissociation of ABE with appearing a free exciton (FE). The PL bands, related to the LO phonon replica of FE and its second-order diffraction, dominate in the PL spectra at room temperature that testify on the high quality of ZnO:Ag films prepared by the USP technology.

Zinc Oxide Thin Films with Reduced Native Compensative Defects Grown by Ultrasonic Spray Pyrolysis at Atmosphere

2007 ◽  
Vol 336-338 ◽  
pp. 589-592
Author(s):  
Jian Ling Zhao ◽  
Xiao Min Li ◽  
Ji Ming Bian ◽  
Wei Dong Yu ◽  
C.Y. Zhang
Keyword(s):  
Spray Pyrolysis ◽  
Deep Level ◽  
Hole Concentration ◽  
Ultrasonic Spray Pyrolysis ◽  
Zno Films ◽  
Near Band Edge ◽  
Dense Microstructure ◽  
Ultrasonic Spray ◽  
High Hole Concentration ◽  
P Type

ZnO films were deposited on Si (100) substrate by ultrasonic spray pyrolysis at atmosphere. The film grown at optimum conditions is well crystallized with uniform, smooth and dense microstructure. Photoluminescence measurement shows a strong near band edge UV emission at 379nm and an almost undetectable deep-level emission band centered at 502nm. The resistivity of ZnO film is reduced by an order after N-In codoping, which produces p-type conduction with high hole concentration and hall mobility.

Photoluminescence of ZnO Nanocrystals Embedded in BaF2 Matrices by Magnetron Sputtering

2008 ◽  
Vol 8 (3) ◽  
pp. 1160-1164
Author(s):  
C. H. Zang ◽  
Y. C. Liu ◽  
R. Mu ◽  
D. X. Zhao ◽  
J. Y. Zhang ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Raman Scattering ◽  
Free Exciton ◽  
Wide Band ◽  
Zno Films ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Ultraviolet Emission ◽  
Pl Spectra ◽  
Zno Nanocrystals

This paper describes ZnO nanocrystals embedded in BaF2 matrices by the magnetron sputtering method in an attempt to use fluoride as a shell layer to embed ZnO nanocrystals core. BaF2 is a wide-band gap material, and can confine carriers in the ZnO films. As a result, the exciton emission intensity should be enhanced. The sample was annealed at 773 K, and X-ray diffraction (XRD) results showed that ZnO nanocrystals with wurtzite structure were embedded in BaF2 matrices. Raman-scattering spectra also confirmed the formation of ZnO nanoparticles. Abnormal longitudinal-optical (LO) phonon-dominant multiphonon Raman scattering was observed in the sample. Room-temperature photoluminescence (PL) spectra showed an ultraviolet emission peak at 374 nm. The origin of the ultraviolet emission is discussed here with the help of temperature-dependent PL spectra. The ultraviolet emission band was a mixture of free exciton and bound exciton recombination observed in the low temperature PL spectra (at 77 K). Abnormal temperature dependence of ultraviolet near-band-edge emission-integrated intensity of the sample was observed. The band tail state was observed in the absorption spectra, illustrating that the impurity-related defects were caused by the shell of the BaF2 grain layer. For comparison, ZnO films on BaF2 substrates were also fabricated by the magnetron sputtering method, and the same measurement methods were used.

scholarly journals Photoluminescence Emission and Structure Study in ZnO:Ag nanorods

2015 ◽  
Vol 5 (01) ◽  
pp. 55
Author(s):  
Erick Velázquez Lozada ◽  
G M Camacho-González ◽  
J M Quino-Cerdan
Keyword(s):  
Optical Properties ◽  
Ultrasonic Spray Pyrolysis ◽  
Structure Study ◽  
Zno Films ◽  
Photoluminescence Spectra ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Structural And Optical Properties ◽  
Ultrasonic Spray ◽  
Different Temperatures

<p>Scanning electronic microscopy (SEM) andX ray diffraction (XRD) have been applied to the study of structural and optical properties of ZnOnanocrystals prepared by the ultrasonic spray pyrolysis (USP) at different temperatures. The variation of temperatures and times at the growth of ZnO films permits modifying the ZnO phase from the amorphous to crystalline, to change the size of ZnOnanocrystals (NCs), as well as to vary their photoluminescence spectra. </p>

Enhanced p-Type ZnO Films through Nitrogen and Argentum Codoping Grown by Ultrasonic Spray Pyrolysis

2008 ◽  
Vol 25 (9) ◽  
pp. 3400-3402 ◽  
Author(s):  
Wang Jing-Wei ◽  
Bian Ji-Ming ◽  
Liang Hong-Wei ◽  
Sun Jing-Chang ◽  
Zhao Jian-Ze ◽  
...  
Keyword(s):  
Spray Pyrolysis ◽  
Ultrasonic Spray Pyrolysis ◽  
Zno Films ◽  
Ultrasonic Spray ◽  
P Type

Study on aluminum concentration on optical and electrical properties of AZO thin films fabricated by ultrasonic spray pyrolysis

2019 ◽  
Vol 33 (22) ◽  
pp. 1950246
Author(s):  
Weiguang Yang ◽  
Miao He ◽  
Liu Yang ◽  
Ziliang Zhou ◽  
Xiaoying Zhang ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Properties ◽  
Spray Pyrolysis ◽  
Quartz Substrate ◽  
Visible Region ◽  
Ultrasonic Spray Pyrolysis ◽  
Aluminum Concentration ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Ultrasonic Spray

In this work, transparent and conductive Al-doped ZnO (AZO) nanofilms were prepared on quartz substrate by ultrasonic spray pyrolysis (USP) method. The effects of Al/Zn atomic ratios on the micro-structural, morphological, optical photoluminescence and electrical properties of AZO thin films were effectively investigated. All the prepared samples showed hexagonal wurtzite structure. The scanning electron microscopy (SEM) showed that the surface morphology of all samples changed with the substrate temperature. The average transmittance of all AZO samples was higher than 85% in the visible region. The photoluminescence (PL) spectrum of the samples showed that the near band edge emission in PL spectra shifted to shorter wavelengths with increasing Al-doped concentration. The lowest sheet resistance was obtained for the samples prepared with 4% at. Al-doped value. The electrical conductivity of AZO films was improved by Al doping, which allowed their use as optoelectronic materials.

scholarly journals Substrate Temperature Effect on Charge Transport Performance of ZnO Electron Transport Layer Prepared by a Facile Ultrasonic Spray Pyrolysis in Polymer Solar Cells

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Jiang Cheng ◽  
Rong Hu ◽  
Qi Wang ◽  
Chengxi Zhang ◽  
Zhou Xie ◽  
...  
Keyword(s):  
Solar Cells ◽  
Spray Pyrolysis ◽  
Polymer Solar Cells ◽  
Acid Methyl Ester ◽  
Ultrasonic Spray Pyrolysis ◽  
Ammonia Solution ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Zno Films ◽  
Ultrasonic Spray

A novel ultrasonic spray pyrolysis for high-quality ZnO films based on zinc-ammonia solution was achieved in air. To investigate the structural and optical properties as well as the performance of polymer solar cells (PSCs), ZnO films at different substrate temperatures and thicknesses were prepared. The performance of poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM) based PSC was found to be improved due to the ZnO films. The crystal structure and roughness of the ZnO films fabricated at different temperatures were found to affect the performance of PSCs. The optimized power conversion efficiency was found to be maximum for PSCs with ZnO films prepared at 200°C. The growth process of these ZnO films is very simple, cost-effective, and compatible for larger-scale PSC preparation. The precursor used for spray pyrolysis is environmentally friendly and helps to achieve ZnO film preparation at a relative low temperature.

Temperature-dependent shifts of near band-edge emission and their second-order diffraction for ZnO nanorods

2012 ◽  
Vol 34 (11) ◽  
pp. 1917-1920 ◽  
Author(s):  
Jianguo Lv ◽  
Changlong Liu ◽  
Wanbing Gong ◽  
Zhenfa Zi ◽  
Xiaoshuang Chen ◽  
...  
Keyword(s):  
Zno Nanorods ◽  
Second Order ◽  
Band Edge ◽  
Near Band Edge Emission ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Temperature Dependent ◽  
Edge Emission ◽  
Order Diffraction

Study on anomalous high p-type conductivity in ZnO films on silicon substrate prepared by ultrasonic spray pyrolysis

2007 ◽  
Vol 90 (6) ◽  
pp. 062118 ◽  
Author(s):  
Jun-Liang Zhao ◽  
Xiao-Min Li ◽  
André Krtschil ◽  
Alois Krost ◽  
Wei-Dong Yu ◽  
...  
Keyword(s):  
Spray Pyrolysis ◽  
Silicon Substrate ◽  
Ultrasonic Spray Pyrolysis ◽  
Zno Films ◽  
Type Conductivity ◽  
Ultrasonic Spray ◽  
P Type
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