Synthesis of Various Nanostructures ZnO and its Applications for Gas Sensors

Several patterns of nanostructures ZnO thin films were successfully synthesized by wet process technique. The nanostructures ZnO thin films were prepared by employing a crystal growth method with zinc nitrate tetrahydrate and ethanol as precursor and solvent, respectively. The resulting mixed solutions were deposited on the different kinds of substrate to yield the variation patterns of nanostructures ZnO including nanorod, flower-like, nanosheet and needle-like patterns. Due to the lack of oxygen on ZnO structure, Al and Sn atom were used as modifier of nanostructure ZnO to enhance the electrochemical properties since we exposed various volatile compounds to it. The crystalinity and compositions were investigated by x-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The nanostructure pattern and surface morphology were confirmed by using scanning electron microscopy (SEM). Moreover, to obtain sensing performance, the nanostructures ZnO were tested in gas sensor testing system consisting of test chamber, data acquisition systems, temperature and gas flow controller.

Download Full-text

The Structural Characterization and Optical Properties of Zinc Oxide Films Synthesized by Electrochemistry Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.743-744.926 ◽

2013 ◽

Vol 743-744 ◽

pp. 926-931

Author(s):

Jing Xia Zheng ◽

Xing Guo Zhao ◽

Wei Liang ◽

Jin Bo Xue

Keyword(s):

Thin Films ◽

Optical Properties ◽

Electrolyte Concentration ◽

Hexagonal Wurtzite Structure ◽

Zinc Nitrate ◽

Zno Thin Films ◽

Zno Films ◽

X Ray Diffraction ◽

Ito Glass ◽

The Matrix

Flaky ZnO thin films were electrodeposited from an aqueous solution of zinc nitrate (Zn (NO3)2) as electrolyte on ITO glass substrate by cathodic reduction method The effect of electrolyte concentration on the structure, morphology and optical properties of ZnO thin films were studied by X-ray diffraction, scanning electron microscopy and UV-Vis spectrometer. The results show that the ZnO films are of hexagonal wurtzite structure; When the concentration of Zn (NO3)2 solution is 0.24 M, the sparse flaky ZnO thin films were prepared and the thickness and length of ZnO flaky are about 50 nm and 1~3 μm, respectively; When the electrolyte concentration is 0.16 M, hexagonal and triangular structures are observed and some lathy and conical ZnO structure start to appear; When the concentration of Zn (NO3)2 solution drops to 0.08 M, the matrix of films is still flaky ZnO, but porous structures among the flaky structures appear and the size of conical ZnO has changed, whose bottom diameter reaches 1~3 μm and length is 2~4 μm; UV-Vis absorption test results indicate the absorption peak and the bandgap of the prepared ZnO thin films are about 350 nm and 3.28 eV, respectively.

Download Full-text

Nonthermal Crystalline Forming of Ceramic Nanoparticles by Non-Equilibrium Excitation Reaction Field of Electron

10.5772/intechopen.97037 ◽

2021 ◽

Author(s):

Norihiro Shimoi

Keyword(s):

Thin Films ◽

Film Formation ◽

High Mobility ◽

Zno Thin Films ◽

Reaction Field ◽

Wet Process ◽

Interface Control ◽

Zno Particles ◽

Pet Film ◽

Non Equilibrium

In this work, we have discovered a method of forming ZnO thin films with high mobility, high carrier density and low resistivity on plastic (PET) films using non-equilibrium reaction fields, even when the films are deposited without heating, and we have also found a thin film formation technique using a wet process that is different from conventional deposition techniques. The field emission electron-beam irradiation treatment energetically activates the surface of ZnO particles and decomposes each ZnO particles. The energy transfer between zinc ions and ZnO surface and the oxygen present in the atmosphere around the ZnO particles induce the oxidation of zinc. In addition, the ZnO thin films obtained in this study successfully possess high functional thin films with high electrical properties, including high hole mobility of 208.6 cm2/Vs, despite being on PET film substrates. These results contribute to the discovery of a mechanism to create highly functional oxide thin films using a simple two-dimensional process without any heat treatment on the substrate or during film deposition. In addition, we have elucidated the interfacial phenomena and crosslinking mechanisms that occur during the bonding of metal oxide particles, and understood the interfacial physical properties and their effects on the electronic structure. and surface/interface control, and control of higher-order functional properties in metal/ceramics/semiconductor composites, and contribute to the provision of next-generation nanodevice components in a broad sense.

Download Full-text

Determination of electrical types in the P-doped ZnO thin films by the control of ambient gas flow

Applied Surface Science ◽

10.1016/j.apsusc.2010.01.035 ◽

2010 ◽

Vol 256 (14) ◽

pp. 4438-4441 ◽

Cited By ~ 9

Author(s):

Young Yi Kim ◽

Won Suk Han ◽

Hyung Koun Cho

Keyword(s):

Thin Films ◽

Gas Flow ◽

Zno Thin Films ◽

Doped Zno ◽

Ambient Gas

Download Full-text

Effect of Flexible Substrates on the Structural and Optical Properties of ZnO Films Deposited by Sputtering Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1107.678 ◽

2015 ◽

Vol 1107 ◽

pp. 678-683 ◽

Cited By ~ 2

Author(s):

Lam Mui Li ◽

Azmizam Manie Mani ◽

Saafie Salleh ◽

Afishah Alias

Keyword(s):

Thin Films ◽

Band Gap ◽

Low Cost ◽

Argon Plasma ◽

Optical Transmittance ◽

Zno Thin Films ◽

Plastic Substrate ◽

Zno Films ◽

X Ray Diffraction ◽

X Ray

Zinc Oxide (ZnO) has attracted much attention because of its high optical transmittance approximately ~80 % with a wide band gap of (3.3 eV at 300 K) and a relatively low cost material. ZnO thin films were deposited on plastic substrate using RF powered magnetron sputtering method. The target used is ZnO disk with 99.99 % purity. The sputtering processes are carried out with argon gas that flow from 10-15 sccm. Argon is used to sputter the ZnO target because the ability of argon that can remove ZnO layer effectively by sputtering with argon plasma bombardment. The deposited ZnO thin films are characterized using X-Ray Diffraction (XRD) and UV-Vis Spectrometer. The analysis of X-ray diffraction show that good crystalline quality occurs at nominal thickness of 400 nm. The optical studies showed that all the thin films have high average transmittance of approximately 80 % and the estimated value of optical band gap is within 3.1 eV-3.3 eV range.

Download Full-text

X-ray diffraction analysis of residual stresses in textured ZnO thin films

Applied Surface Science ◽

10.1016/j.apsusc.2016.06.060 ◽

2017 ◽

Vol 395 ◽

pp. 16-23 ◽

Cited By ~ 11

Author(s):

E. Dobročka ◽

P. Novák ◽

D. Búc ◽

L. Harmatha ◽

J. Murín

Keyword(s):

Thin Films ◽

Residual Stresses ◽

Diffraction Analysis ◽

Zno Thin Films ◽

X Ray Diffraction ◽

X Ray

Download Full-text

Electron carrier concentration dependent magnetization in ZnO:Co and ZnO:Mn thin films

MRS Proceedings ◽

10.1557/proc-1035-l06-06 ◽

2007 ◽

Vol 1035 ◽

Author(s):

Zheng Yang ◽

Maurizio Biasini ◽

Leelaprasanna J Mandalapu ◽

Zheng Zuo ◽

Ward P Beyermann ◽

...

Keyword(s):

Thin Films ◽

Carrier Concentration ◽

Concentration Dependence ◽

Long Range ◽

Room Temperature ◽

Zno Thin Films ◽

X Ray Diffraction ◽

Electron Carrier ◽

X Ray ◽

Curie Temperatures

AbstractCo and Mn ions were implanted into n-type ZnO thin films with different electron carrier concentrations. X-ray diffraction measurements show that the ZnO:Co and ZnO:Mn thin films are of high crystallinity. From magnetization measurements, ferromagnetism was observed in both n-type ZnO:Co and n-type ZnO:Mn thin films with Curie temperatures well-above room temperature. Furthermore, the electron carrier concentration dependence of the saturated magnetization was measured in both types of thin films, and our results support an electron-mediated mechanism for ferromagnetism in ZnO:Co, as predicted by theory. However, our measurements seem to contradict theory for ZnO:Mn, which only predicts long-range ferromagnetism for p-type mediated material.

Download Full-text

Structural properties of low-temperature grown ZnO thin films determined by X-ray diffraction and X-ray absorption spectroscopy

Thin Solid Films ◽

10.1016/j.tsf.2011.02.009 ◽

2011 ◽

Vol 519 (13) ◽

pp. 4366-4370 ◽

Cited By ~ 7

Author(s):

Chung-Jong Yu ◽

Nark-Eon Sung ◽

Han-Koo Lee ◽

Hyun-Joon Shin ◽

Young-Duck Yun ◽

...

Keyword(s):

Thin Films ◽

Low Temperature ◽

Structural Properties ◽

Absorption Spectroscopy ◽

Zno Thin Films ◽

X Ray Diffraction ◽

X Ray ◽

X Ray Absorption

Download Full-text

Origin of Ultraviolet Luminescence from Bulk ZnO Thin Films Grown by Molecular Beam Epitaxy

Advanced Engineering Forum ◽

10.4028/www.scientific.net/aef.1.135 ◽

2011 ◽

Vol 1 ◽

pp. 135-139 ◽

Cited By ~ 1

Author(s):

M. Asghar ◽

Khalid Mahmood ◽

Adnan Ali ◽

M.A. Hasan ◽

I. Hussain ◽

...

Keyword(s):

Thin Films ◽

Raman Spectroscopy ◽

Molecular Beam Epitaxy ◽

Room Temperature ◽

Molecular Beam ◽

Energy Dispersive ◽

Zno Thin Films ◽

X Ray Diffraction ◽

X Ray ◽

Uv Luminescence

Origin of ultraviolet (UV) luminescence from bulk ZnO has been investigated with the help of photoluminescence (PL) measurements. Thin films of ZnO having 52%, 53% and 54% of Zn-contents were prepared by means of molecular beam epitaxy (MBE). We observed a dominant UV line at 3.28 eV and a visible line centered at 2.5 eV in the PL spectrum performed at room temperature. The intensity of UV line has been found to depend upon the Zn percentage in the ZnO layers. Thereby, we correlate the UV line in our samples with the Zn-interstitials-bound exciton (Zni-X) recombination. The results obtained from, x-ray diffraction, the energy dispersive X-ray spectrum (EDAX) and Raman spectroscopy supported the PL results.

Download Full-text

Internal Stress of ZnO thin Films Caused by Thickness Distribution and Crystallinity

MRS Proceedings ◽

10.1557/proc-518-215 ◽

1998 ◽

Vol 518 ◽

Cited By ~ 2

Author(s):

M. Takeuchi ◽

K. Inoue ◽

Y. Yoshino ◽

K. Ohwada

Keyword(s):

Thin Films ◽

Stress Distribution ◽

Thickness Distribution ◽

Zno Thin Films ◽

Optimum Thickness ◽

X Ray Diffraction ◽

Axis Orientation ◽

X Ray ◽

Argon Ions ◽

Cosine Law

AbstractThe improvement of thickness distribution and crystallinity in ZnO thin films prepared by radio frequency (rf) planer magnetron sputtering has been studied. Optimum thickness distribution of less than ± 2.2% in a 3-inch wafer is obtained by changing the substrate angle to the ZnO target and is in accordance with cosine law. The c-axis orientation perpendicular to the silicon substrate is confirmed by x-ray diffraction. The stress of ZnO thin films is larger than 0.3GPa and its distribution is independent of the substrate angle that is set at a slant to the optimum angle for thickness distribution. These results indicate that thickness distribution of ZnO thin films heavily depends on the substrate angle, while the stress and its distribution are independent of the setting angle of the substrate. Stress distribution is attributed to the distribution of argon ions and sputtered molecules impinging a wafer.

Download Full-text