scholarly journals Tailoring the Grain Size of Bi-Layer Graphene by Pulsed Laser Deposition

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 885 ◽  
Author(s):  
Jin Wang ◽  
Xuemin Wang ◽  
Jian Yu ◽  
Tingting Xiao ◽  
Liping Peng ◽  
...  
Keyword(s):  
Grain Size ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Photoelectron Spectra ◽  
Laser Deposition ◽  
Stable Region ◽  
Thermoelectric Efficiency ◽  
Sem Images ◽  
Hybrid State ◽  
Layer Graphene

Improving the thermoelectric efficiency of a material requires a suitable ratio between electrical and thermal conductivity. Nanostructured graphene provides a possible route to improving thermoelectric efficiency. Bi-layer graphene was successfully prepared using pulsed laser deposition in this study. The size of graphene grains was controlled by adjusting the number of pulses. Raman spectra indicated that the graphene was bi-layer. Scanning electron microscopy (SEM) images clearly show that graphene changes from nanostructured to continuous films when more pulses are used during fabrication. Those results indicate that the size of the grains can be controlled between 39 and 182 nm. A detailed analysis of X-ray photoelectron spectra reveals that the sp2 hybrid state is the main chemical state in carbon. The mobility is significantly affected by the grain size in graphene, and there exists a relatively stable region between 500 and 800 pulses. The observed phenomena originate from competition between decreasing resistance and increasing carrier concentration. These studies should be valuable for regulating grains sizes for thermoelectric applications of graphene.

scholarly journals Development of Pd/TiO2 Porous Layers by Pulsed Laser Deposition for Surface Acoustic Wave H2 Gas Sensor

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 760 ◽  
Author(s):  
Izabela Constantinoiu ◽  
Cristian Viespe
Keyword(s):  
Acoustic Wave ◽  
Frequency Shift ◽  
Pulsed Laser Deposition ◽  
Surface Acoustic Wave ◽  
Limit Of Detection ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
High Porosity ◽  
Porous Films ◽  
Sem Images

The influence of sensitive porous films obtained by pulsed laser deposition (PLD) on the response of surface acoustic wave (SAW) sensors on hydrogen at room temperature (RT) was studied. Monolayer films of TiO2 and bilayer films of Pd/TiO2 were deposited on the quartz substrates of SAW sensors. By varying the oxygen and argon pressure in the PLD deposition chamber, different morphologies of the sensitive films were obtained, which were analyzed based on scanning electron microscopy (SEM) images. SAW sensors were realized with different porosity degrees, and these were tested at different hydrogen concentrations. It has been confirmed that the high porosity of the film and the bilayer structure leads to a higher frequency shift and allow the possibility to make tests at lower concentrations. Thus, the best sensor, Pd-1500/TiO2-600, with the deposition pressure of 600 mTorr for TiO2 and 1500 mTorr for Pd, had a frequency shift of 1.8 kHz at 2% hydrogen concentration, a sensitivity of 0.10 Hz/ppm and a limit of detection (LOD) of 1210 ppm. SAW sensors based on such porous films allow the detection of hydrogen but also of other gases at RT, and by PLD method such sensitive porous and nanostructured films can be easily developed.

scholarly journals The Properties of Zn-Doped AlSb Thin Films Prepared by Pulsed Laser Deposition

Coatings ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 136
Author(s):  
Ping Tang ◽  
Weimin Wang ◽  
Bing Li ◽  
Lianghuan Feng ◽  
Guanggen Zeng
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Pulsed Laser Deposition ◽  
Band Gap ◽  
Photovoltaic Effect ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Sem Images ◽  
Glass Substrates ◽  
Substrate Temperatures

Aluminum antimony (AlSb) is a promising photovoltaic material with a band gap of about 1.62 eV. However, AlSb is highly deliquescent and not stable, which has brought great difficulties to the applications. Based on the above situation, there are two purposes for preparing our Zn-doped AlSb (AlSb:Zn) thin films: One is to make P-type AlSb and the other is to find a way to suppress the deliquescence of AlSb. The AlSb:Zn thin films were prepared on glass substrates at different substrate temperatures by using the pulsed laser deposition (PLD) method. The structural, surface morphological, optical, and electrical properties of AlSb:Zn films were investigated. The crystallization of AlSb:Zn thin films was enhanced and the electrical resistivity decreased as the substrate temperature increased. The scanning electron microscopy (SEM) images indicated that the grain sizes became bigger as the substrate temperatures increased. The Raman vibration mode AlSb:Zn films were located at ~107 and ~142 cm−1 and the intensity of Raman peaks was stronger at higher substrate temperatures. In the experiment, a reduced band gap (1.4 eV) of the AlSb:Zn thin film was observed compared to the undoped AlSb films, which were more suitable for thin-film solar cells. Zn doping could reduce the deliquescent speed of AlSb thin films. The fabricated heterojunction device showed the good rectification behavior, which indicated the PN junction formation. The obvious photovoltaic effect has been observed in an FTO/ZnS/AlSb:Zn/Au device.

Synthesis of ZnO Nanowires by Pulsed Laser Deposition in Furnace

2005 ◽  
Vol 900 ◽  
Author(s):  
Kyung Ah Jeon ◽  
Hyo Jeong Son ◽  
Jong Hoon Kim ◽  
K. H. Yoo ◽  
Sang Yeol Lee
Keyword(s):  
Pulsed Laser Deposition ◽  
Deep Level ◽  
Average Length ◽  
Green Light ◽  
Pulsed Laser ◽  
Zno Nanowires ◽  
Laser Deposition ◽  
Near Band Edge ◽  
Vacuum Furnace ◽  
Sem Images

ABSTRACTZnO nanowires (NWs) were fabricated on Au coated sapphire (0001) substrates by using a pulsed laser deposition (PLD) system in vacuum furnace with a Q-switched Nd:YAG laser. ZnO NWs have various size and shape with a substrate position inside a furnace, and their morphologic construction is reproducible. Scanning electron microscopy (SEM) images indicate that the diameters of ZnO NWs ranged from 100 to 150 nm and the average length was greater than 3 μm. Room-temperature photoluminescence spectra of the NWs show the near band-edge emissions and the deep-level green light emissions. The formation mechanism of the NWs is discussed.

Growth of Textured Nanocrystalline Cobalt Ferrite Thin Films by Pulsed Laser Deposition

2008 ◽  
Vol 8 (8) ◽  
pp. 4135-4140 ◽  
Author(s):  
Lakshmikanta Aditya ◽  
A. Srivastava ◽  
S. K. Sahoo ◽  
P. Das ◽  
C. Mukherjee ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Pulsed Laser Deposition ◽  
Cobalt Ferrite ◽  
Pulsed Laser ◽  
Grazing Incidence ◽  
Orientation Distribution ◽  
Laser Deposition ◽  
X Ray ◽  
Ferrite Thin Films

Cobalt ferrite thin films have been deposited on fused quartz substrates by pulsed laser deposition at various substrate temperatures, TS (25 °C, 300 °C, 550 °C and 750 °C). Single phase, nanocrystalline, spinel cobalt ferrite formation is confirmed by X-ray diffraction (XRD) for TS ≥ 300 °C. Conventional XRD studies reveal strong (111) texturing in the as deposited films with TS ≥ 550 °C. Bulk texture measurements using X-ray orientation distribution function confirmed (111) preferred orientation in the films with TS ≥ 550 °C. Grain size (13–16 nm for TS ≥ 300 °C) estimation using grazing incidence X-ray line broadening analysis shows insignificant grain growth with increasing TS, which is in good agreement with grain size data obtained from transmission electron microscopy.

Grain size, texture, and crystallinity in lanthanum monosulfide thin films grown by pulsed laser deposition

2012 ◽  
Vol 524 ◽  
pp. 166-172 ◽  
Author(s):  
S. Fairchild ◽  
M. Cahay ◽  
P.T. Murray ◽  
L. Grazulis ◽  
X. Wu ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Lanthanum Monosulfide

Novel Nanocrystalline Materials by Pulsed Laser Deposition

2000 ◽  
Vol 617 ◽  
Author(s):  
J. Narayan ◽  
A.K. Sharma ◽  
A. Kvit ◽  
D. Kumar ◽  
J.F. Muth
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Grain Boundary Sliding ◽  
Laser Deposition ◽  
Nanocrystalline Metal ◽  
Potential Applications ◽  
Novel Method ◽  
Boundary Sliding

AbstractWe have developed a novel method based upon pulsed laser deposition to produce nanocrystalline metal, semiconductor and magnetic material thin films and composites. The size of nanocrystals was controlled by interfacial energy, number of monolayers and substrate temperature. By incorporating a few monolayers of W during PLD, the grain size of copper nanocrystals was reduced from 160nm (Cu on Si (100)) to 4nm for a multilayer (Cu/W/Cu/W/Si (100)) thin film. The hardness increased with decreasing grain size up to a certain value (7nm in the case of copper) and then decreased below this value. While the former is consistent with Hall-Petch model, the latter involves a new model based upon grain boundary sliding.We have used the same PLD approach to form nanocrystalline metal (Ni, Co, Fe embedded in α-A12O3 and MgO) and semiconductor (Si, Ge, ZnO, GaN embedded in AIN and α-A12O3) thin films. These nanocrystalline composites exhibit novel magnetic properties and novel optoelectronic properties with quantum confinement of electrons, holes and excitons in semiconductors. We review advanced PLD processing, detailed characterization, structureproperty correlations and potential applications of these materials.

Growth and Characterization of Titanium Nitride Nanowires on Silicon Substrate Using Pulsed Laser Deposition Method for Biological Applications

2013 ◽  
Author(s):  
Seyram Gbordzoe ◽  
K. Mensah-Darkwa ◽  
Ram Gupta ◽  
Dhananjay Kumar
Keyword(s):  
Titanium Nitride ◽  
Pulsed Laser Deposition ◽  
Silicon Substrate ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Single Crystal Silicon ◽  
Laser Deposition ◽  
Sem Images ◽  
Crystal Silicon

The present work reports on the growth and characterization of titanium nitride (TiN) nanowires on silicon substrate using a pulsed laser deposition (PLD) method. The TiN nanowires were grown on single crystal silicon substrate with (100) and (111) orientations at a range of substrate temperatures and under both nitrogen ambient and vacuum. The different orientation of silicon was chosen to see the effect of the substrate orientation on the growth of TiN nanowires. The laser energy entering the vacuum chamber to impinge the TiN target for nanowire deposition was varied from 70 to 80 mJ. The TiN nanowires samples were characterized using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). The diameter of the nanowires was observed to increase from 25 nm to 40 nm with an increase in laser beam energy entering the chamber. The shape and orientation of the nanowires was observed to be the same for (100) and (111) oriented silicon substrates as observed in SEM images. Corrosion tests were also conducted on the TiN nanowires.

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