scholarly journals Graphene Langmuir-Schaefer films Decorated by Pd Nanoparticles for NO2 and H2 Gas Sensors

2019 ◽  
Vol 19 (2) ◽  
pp. 64-69 ◽  
Author(s):  
Dmytro Kostiuk ◽  
Stefan Luby ◽  
Peter Siffalovic ◽  
Monika Benkovicova ◽  
Jan Ivanco ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Pd Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Si Substrates ◽  
Long Term Stability ◽  
Atomic Force ◽  
Few Layer Graphene

Abstract NO2 and H2 gas sensing by few-layer graphene (FLG) were studied in dependence on the annealing and decoration of graphene by palladium nanoparticles (NPs). Graphene was deposited onto SiO2 (500 nm)/Si substrates by a modified Langmuir-Schaefer technique. A solution of FLG flakes in 1-methyl-2-pyrrolidone was obtained by a mild sonication of the expanded milled graphite. FLG films were characterized by atomic force microscopy, X-ray diffraction, Raman spectroscopy, and the Brunnauer-Emmett-Teller method. Average FLG flake thickness and lateral dimension were 5 nm and 300 nm, respectively. Drop casting of Pd NP (6–7 nm) solution onto FLG film was applied to decorate graphene by Pd. The room temperature (RT) resistance of the samples was stabilized at 15 kΩ by vacuum annealing. Heating cycles of FLG film revealed its semiconducting character. The gas sensing was tested in the mixtures of dry air with H2 gas (10 to 10 000 ppm) and NO2 gas (2 to 200 ppm) between RT and 200 °C. The response of 26 % to H2 was achieved by FLG with Pd decoration at 70 °C and 10 000 ppm of H2 in the mixture. Pure FLG film did not show any response to H2. The response of FLG with Pd to 6 ppm of NO2 at RT was ≥ 23 %. It is 2 times larger than that of the pure FLG sample. Long term stability of sensors was studied.

Investigation of the Effect of Uv-Assisted Oxidation and Nitridation of Hafnium Metal Films

2003 ◽  
Vol 780 ◽  
Author(s):  
C. Essary ◽  
V. Craciun ◽  
J. M. Howard ◽  
R. K. Singh
Keyword(s):  
Uv Radiation ◽  
Photoelectron Spectroscopy ◽  
Grazing Angle ◽  
X Ray Diffraction ◽  
Metal Thin Films ◽  
X Ray ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Silicon Interface

AbstractHf metal thin films were deposited on Si substrates using a pulsed laser deposition technique in vacuum and in ammonia ambients. The films were then oxidized at 400 °C in 300 Torr of O2. Half the samples were oxidized in the presence of ultraviolet (UV) radiation from a Hg lamp array. X-ray photoelectron spectroscopy, atomic force microscopy, and grazing angle X-ray diffraction were used to compare the crystallinity, roughness, and composition of the films. It has been found that UV radiation causes roughening of the films and also promotes crystallization at lower temperatures.Furthermore, increased silicon oxidation at the interface was noted with the UVirradiated samples and was shown to be in the form of a mixed layer using angle-resolved X-ray photoelectron spectroscopy. Incorporation of nitrogen into the film reduces the oxidation of the silicon interface.

Reactive Sputtering Growth and Characterizations of InN Thin Films on Si Substrates

2012 ◽  
Vol 545 ◽  
pp. 290-293
Author(s):  
Maryam Amirhoseiny ◽  
Hassan Zainuriah ◽  
Ng Shashiong ◽  
Mohd Anas Ahmad
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Rf Magnetron Sputtering ◽  
Rf Power ◽  
X Ray Diffraction ◽  
Nitrogen Gas ◽  
X Ray ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force

We have studied the effects of deposition conditions on the crystal structure of InN films deposited on Si substrate. InN thin films have been deposited on Si(100) substrates by reactive radio frequency (RF) magnetron sputtering method with pure In target at room temperature. The nitrogen gas pressure, applied RF power and the distance between target and substrate were 2×10-2 Torr, 60 W and 8 cm, respectively. The effects of the Ar–N2 sputtering gas mixture on the structural properties of the films were investigated by using scanning electron microscope, energy-dispersive X-ray spectroscopy, atomic force microscopy and X-ray diffraction techniques.

Influence of Ammonia on the Fabrication of Aligned Carbon Nanotubes Using Thermal CVD

2011 ◽  
Vol 467-469 ◽  
pp. 312-315
Author(s):  
Gang Li ◽  
Wen Ming Cheng
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Vertical Alignment ◽  
X Ray ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Aligned Carbon Nanotubes ◽  
20 Nm

Ultra-thin (20 nm) nickel catalyst films were deposited by sputtering on SiO2/Si substrates. At the pretreatments, ammonia (NH3) was conducted for different time in a thermal chemical vapor deposition (CVD) system. Pretreated samples were characterized using atomic force microscopy (AFM). After the pretreatment, acetylene was introduced into the chamber for 10 min, samples were characterized using scanning electron micrograph (SEM) and X-ray diffraction (XRD). It was concluded that NH3 pretreatment was very crucial to control the surface morphology of catalytic metals and thus to achieve the vertical alignment of carbon nanotubes (CNTs). With higher density of the Ni particles, better alignment of the CNTs can be obtained due to steric hindrance effect between neighboring CNTs.

Low Temperature Chemical Vapor Deposition of 3C-SiC on Si Substrates

2005 ◽  
Vol 483-485 ◽  
pp. 201-204 ◽  
Author(s):  
Christian Förster ◽  
Volker Cimalla ◽  
Oliver Ambacher ◽  
Jörg Pezoldt
Keyword(s):  
Gas Phase ◽  
Vapor Deposition ◽  
Growth Process ◽  
Chemical Vapor ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force

In the present work an UHVCVD method was developed which allows the epitaxial growth of 3C-SiC on Si substrates at temperatures below 1000°C. The developed method enable the growth of low stress or nearly stress free single crystalline 3C-SiC layers on Si. The influence of hydrogen on the growth process are be discussed. The structural properties of the 3C-SiC(100) layers were studied with reflection high-energy diffraction, atomic force microscopy, X-ray diffraction and the layer thickness were measured by reflectometry as well as visible ellipsometry. The tensile strain reduction at optimized growth temperature, Si/C ratio in the gas phase and deposition rate are demonstrated by the observation of freestanding SiC cantilevers.

STRUCTURE AND PHOTOLUMINESCENT PROPERTIES OF SiCO THIN-FILMS DOPED WITH Al PREPARED BY DUAL MAGNETRON SPUTTERING

2011 ◽  
Vol 25 (16) ◽  
pp. 2149-2156
Author(s):  
JICHENG ZHOU ◽  
XUQIANG ZHENG ◽  
ZHIJIE SHI ◽  
BAOXING ZHAO ◽  
FU LIU ◽  
...  
Keyword(s):  
Thin Films ◽  
Energy Dispersive Spectrometer ◽  
Thin Layers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Related Defect ◽  
Amorphous Sic

SiCO thin-films doped with aluminum (Al) prepared by alternate deposition of SiC and Al thin layers using Ar and O 2 as sputtering gas were deposited on n- Si substrates. The as-deposited thin-films were annealed under 600°C in nitrogen ambient. The thin-films have been characterized by atomic force microscopy, energy dispersive spectrometer, X-ray diffraction, fourier transform infrared spectroscopy, and photoluminescence spectra. The results showed that the introduction of Al promotes the formation of Si — C bonds, but hinders amorphous SiC to further transform to crystalline SiC . The doped Al would react with SiO x in the thin-films to form more Si particles which strongly affect the optical properties. After Al doped, there presented a seven times of enhancement emission band centered around 412 nm, which is ascribed to nanostructure Si -related defect centers embedded in the SiCO thin-films. The obtained results are expected to have important applications in modern optoelectronic devices.

scholarly journals Influence of GLAD Sputtering Configuration on the Crystal Structure, Morphology, and Gas-Sensing Properties of the WO3 Films

Coatings ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1030
Author(s):  
Arkadiusz Zarzycki ◽  
Katarzyna Dyndał ◽  
Maciej Sitarz ◽  
Jie Xu ◽  
Feng Gao ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Gas Content ◽  
Exhaled Breath ◽  
X Ray Diffraction ◽  
Gas Sensitivity ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Structure Morphology ◽  
Breath Acetone

In this paper, we describe a deposition method and investigation of the physical properties of WO3 films. We investigated tungsten oxide due to its potential application as a gas sensor. Thin films of the WO3 were deposited on glass, silicon, and alumina substrates by magnetron GLAD sputtering. The crystallinity of films was determined by X-ray diffraction (XRD) and the thickness by X-Ray Reflectivity (XRR) and spectroscopic ellipsometry (SE). Surface morphology, which is important for gas sensitivity, was measured by atomic force microscopy (AFM). We studied the gas-sensing characteristics under exposure to acetone in the 0.1–1.25 ppm range which covers the levels of exhaled breath acetone. We show that WO3 sensors have different sensitivity for different sputter angle. Furthermore, we demonstrate the influence of temperature during gas content measurement.

Growth of 3C-SiC on Si: Influence of Process Pressure

2008 ◽  
Vol 600-603 ◽  
pp. 211-214 ◽  
Author(s):  
Andrea Severino ◽  
Christopher L. Frewin ◽  
Ruggero Anzalone ◽  
Corrado Bongiorno ◽  
Patrick Fiorenza ◽  
...  
Keyword(s):  
Growth Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
Process Pressure ◽  
Flat Film ◽  
Afm Analysis

In this work a comparison between atmospheric pressure (AP) and low pressure (LP) carbonization as the first step in the growth process of 3C-SiC on Si substrates is presented. Three different Si substrate orientations have been studied and compared. Characterization analysis has been performed by Atomic Force Microscopy (AFM), X-ray Diffraction Spectroscopy (XRD) and Transmission Electron Microscopy (TEM). XRD and AFM analysis show a lower roughness and a better quality for LPCVD carbonized samples. Substrate orientation plays an important role both in the generation as well as in the effect of such defects in the subsequent growth process, leading to a rougher SiC surface for growth on (110) Si while micro-twin effects are limited for growth on (111) Si, resulting in an extremely flat film.

Low Molecular Weight Microfibers with Light Sensing Properties

2017 ◽  
Vol 54 (4) ◽  
pp. 655-658
Author(s):  
Andrei Bejan ◽  
Dragos Peptanariu ◽  
Bogdan Chiricuta ◽  
Elena Bicu ◽  
Dalila Belei
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
X Ray Diffraction ◽  
Aromatic Rings ◽  
X Ray ◽  
Force Microscopy ◽  
Light Sensing ◽  
Sensing Applications ◽  
Atomic Force ◽  
Low Molecular Weight Compounds

Microfibers were obtained from organic low molecular weight compounds based on heteroaromatic and aromatic rings connected by aliphatic spacers. The obtaining of microfibers was proved by scanning electron microscopy. The deciphering of the mechanism of microfiber formation has been elucidated by X-ray diffraction, infrared spectroscopy, and atomic force microscopy measurements. By exciting with light of different wavelength, florescence microscopy revealed a specific optical response, recommending these materials for light sensing applications.

Nanocrystalline Solutions as Precursors to The Spray Deposition of Cdte Thin Films

1995 ◽  
Vol 382 ◽  
Author(s):  
Martin Pehnt ◽  
Douglas L. Schulz ◽  
Calvin J. Curtis ◽  
Helio R. Moutinho ◽  
Amy Swartzlander ◽  
...  
Keyword(s):  
Thin Films ◽  
Atomic Force Microscopy ◽  
Grain Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Cdte Nanoparticles ◽  
Atomic Force ◽  
Vis Spectroscopy ◽  
Cdte Thin Films

ABSTRACTIn this article we report the first nanoparticle-derived route to smooth, dense, phase-pure CdTe thin films. Capped CdTe nanoparticles were prepared by injection of a mixture of Cd(CH3)2, (n-C8H17)3 PTe and (n-C8H17)3P into (n-C8H17)3PO at elevated temperatures. The resultant nanoparticles 32-45 Å in diameter were characterized by x-ray diffraction, UV-Vis spectroscopy, transmission electron microscopy, thermogravimetric analysis and energy dispersive x-ray spectroscopy. CdTe thin film deposition was accomplished by dissolving CdTe nanoparticles in butanol and then spraying the solution onto SnO2-coated glass substrates at variable susceptor temperatures. Smooth and dense CdTe thin films were obtained using growth temperatures approximately 200 °C less than conventional spray pyrolysis approaches. CdTe films were characterized by x-ray diffraction, UV-Vis spectroscopy, atomic force microscopy, and Auger electron spectroscopy. An increase in crystallinity and average grain size as determined by x-ray diffraction was noted as growth temperature was increased from 240 to 300 °C. This temperature dependence of film grain size was further confirmed by atomic force microscopy with no remnant nanocrystalline morphological features detected. UV-Vis characterization of the CdTe thin films revealed a gradual decrease of the band gap (i.e., elimination of nanocrystalline CdTe phase) as the growth temperature was increased with bulk CdTe optical properties observed for films grown at 300 °C.

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