Comparison of Vanadium Oxide Thin Films Prepared Using Femtosecond and Nanosecond Pulsed Laser Deposition

MRS Advances ◽  
2016 ◽  
Vol 1 (39) ◽  
pp. 2737-2742 ◽  
Author(s):  
Ying Deng ◽  
Anthony Pelton ◽  
R. A. Mayanovic

ABSTRACTPulsed laser deposition (PLD) is a technique which utilizes a high energy pulsed laser ablation of targets to deposit thin films on substrates in a vacuum chamber. The high-intensity laser pulses create a plasma plume from the target material which is projected towards the substrate whereupon it condenses to deposit a thin film. Here we investigate the properties of vanadium oxide thin films prepared utilizing two variations of the pulsed laser deposition (PLD) technique: femtosecond PLD and nanosecond PLD. Femtosecond PLD (f-PLD) has a significantly higher peak intensity and shorter duration laser pulse compared to that of the excimer-based nanosecond PLD (n-PLD). Experiments have been conducted on the growth of thin films prepared from V2O5 targets on glass substrates using f-PLD and n-PLD. Characterization using SEM, XRD and Raman spectroscopy shows that the f-PLD films have significantly rougher texture prior to annealing and exhibit with an amorphous nano-crystalline character whereas the thin films grown using n-PLD are much smoother and highly predominantly amorphous. The surface morphology, structural, vibrational, and chemical- and electronic-state elemental properties of the vanadium oxide thin films, both prior to and after annealing to 450 °C, will be discussed.

2008 ◽  
Vol 8 (5) ◽  
pp. 2604-2608 ◽  
Author(s):  
Y. L. Wang ◽  
M. C. Li ◽  
X. K. Chen ◽  
G. Wu ◽  
J. P. Yang ◽  
...  

Nano-polycrystalline vanadium oxide thin films have been successfully produced by pulsed laser deposition on Si(100) substrates using a pure vanadium target in an oxygen atmosphere. The vanadium oxide thin film is amorphous when deposited at relatively low substrate temperature (500 °C) and enhancing substrate temperature (600–800 °C) appears to be efficient in crystallizing VOx thin films. Nano-polycrystalline V3O7 thin film has been achieved when deposited at oxygen pressure of 8 Pa and substrate temperature of 600 °C. Nano-polycrystalline VO2 thin films with a preferred (011) orientation have been obtained when deposited at oxygen pressure of 0.8 Pa and substrate temperatures of 600–800 °C. The vanadium oxide thin films deposited at high oxygen pressure (8 Pa) reveal a mix-valence of V5+ and V4+, while the VOx thin films deposited at low oxygen pressure (0.8 Pa) display a valence of V4+. The nano-polycrystalline vanadium oxide thin films prepared by pulsed laser deposition have smooth surface with high qualities of mean crystallite size ranging from 30 to 230 nm and Ra ranging from 1.5 to 22.2 nm. Relative low substrate temperature and oxygen pressure are benifit to aquire nano-polycrystalline VOx thin films with small grain size and low surface roughness.


2003 ◽  
Vol 780 ◽  
Author(s):  
Eric Millon ◽  
Jacques Perrière ◽  
Olivier Albert ◽  
Jean Etchepare ◽  
Chantal Boulmer-Leborgne

AbstractThe femtosecond (fs) lasers display noticeable specificities compared with the nanosecond (ns) ones operating in the UV domain, and classically used for the pulsed-laser deposition (PLD) technique. The ultra-short laser pulses offer the feature of minimal thermal damage induced in the target material, and the very high intensities (1012-14 W/cm2) available with fs lasers are likely to allow the ablation of any kind of materials, even the wide band gap insulators.The morphology, structure, composition and properties of the films obtained by fs PLD are studied according to the experimental growth conditions, the nature of the target material, and the dynamic expansion of plasma plume. In the case of ZnO, smooth, dense and nanocrystalline films (10 to 30 nm crystallites) can be epitaxially grown on adequate substrates (i.e. sapphire). On the contrary, BaTiO3 films are formed by the random stacking of aggregates (10 to 200 nm) leading to a non negligible surface roughness,. In addition, the chemical composition of fs PLD thin films of multicomponent compound (i.e. BaTiO3) is not homogeneous, an enrichment in the lighter element being observed in the central part of the film. These properties are related to the phenomena taking place during the various steps of the process (laser-matter interaction, plasma formation, expansion) through time resolved emission spectroscopy and plume optical imaging measurements.


1998 ◽  
Vol 555 ◽  
Author(s):  
H. Fritze ◽  
A. Schnittker ◽  
T. Witke ◽  
C. Rüscher ◽  
S. Weber ◽  
...  

AbstractPulsed Laser Deposition (PLD) allows the ablation of nonconductive and high melting point target materials and the preparation of films with complex composition. High energy impact leads to melting and evaporation of the target material in a single step. In case of mullite ablation, the flux of the metal components is stoichiometric. Under reduced pressure the oxygen content in the layers decreases. However, after a short oxidation treatment, the formation of mullite in the coating is completed, as confirmed by IR spectroscopy and XRD investigations. For a commercial Si-SiC precoated C/C material, the effectiveness of additional PLD mullite layers as outer oxidation protection is tested in the temperature range 773 K < T < 1873 K. Mullite coatings with a thickness of 2.5 pm improve the oxidation behaviour significantly. Because of SiO2 formation at the mullite-SiC interface, all samples exhibited a mass increase upon oxidation. For oxidation durations of three days, only amorphous SiO2 is formed at the mullite-SiC interface. The inward diffusion of oxygen across the outer mullite-containing layer controls the kinetics of the reaction, as was deduced from 18O diffusivity measurements in PLD mullite layers. At temperatures close to the eutectic temperature (1860 K), mullite can seal defects. The calculated oxidation rates resulting from the diffusion parameters in SiO2 and mullite are close to the thermogravimetric data.


2021 ◽  
pp. 126323
Author(s):  
Joseph A. De Mesa ◽  
Angelo P. Rillera ◽  
Melvin John F. Empizo ◽  
Nobuhiko Sarukura ◽  
Roland V. Sarmago ◽  
...  

1996 ◽  
Vol 69 (14) ◽  
pp. 2027-2029 ◽  
Author(s):  
M. A. El Khakani ◽  
M. Chaker ◽  
E. Gat

Sign in / Sign up

Export Citation Format

Share Document