DROPLETS AND OUTGROWTHS ON HIGH-Tc LASER ABLATED THIN FILMS

IJsselsteijn, R.P.J.; Blank, David H.A.; Out, P.; Roesthuis, F.J.G.; Flokstra, Jakob; Rogalla, Horst

doi:10.1016/b978-0-444-89353-6.50044-0

Cited by 5 publications

(5 citation statements)

References 8 publications

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“…We have observed nearly equivalent results from all the targets we have tried, which is consistent with results reported in [3]. Some groups report that the target density or structure determines the occurrence of droplets, while other groups find no such dependence.…”

Section: Methodssupporting

confidence: 90%

“…Films with the best surface morphology appear to be possible only at a lower substrate temperature and over a much narrower range of temperatures than reported for direct deposition on substrates that do not require buffer layers [2,3,6]. Films with the best surface morphology appear to be possible only at a lower substrate temperature and over a much narrower range of temperatures than reported for direct deposition on substrates that do not require buffer layers [2,3,6].…”

Section: Introductionmentioning

confidence: 80%

“…IJsselstein et al 3 reported on films deposited on SrTiO3 and Zr02 substrates using a 308 nm XeCl laser. There have been a number of studies on the relationship between process parameters and surface morphology of YBCO films deposited by laser ablation.…”

Section: Introductionmentioning

confidence: 99%

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<title>Investigation of substrate temperature effect on the surface morphology of excimer laser deposited YBa<formula><inf><roman>2</roman></inf></formula>Cu<formula><inf><roman>3</roman></inf></formula>O<formula><inf><roman>7</roman></inf></formula>/CeO<formula><inf><roman>2</roman></inf></formula> films on sapphire</title>

1994

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Excimer laser ablation is an excellent means of depositing high temperature superconducting (HTS) thin films because of high quality electrical properties of the resulting films and also because of the relative simplicity of the deposition system. The principal disadvantage of laser ablation is the contamination of the deposited film by particles, leading to a rough film surface. The influence of substrate temperature on surface morphology in YBa2Cu3O7 thin films deposited by excimer laser on r-plane sapphire with a CeO2 buffer layer has been investigated. The substrate temperature was measured using gold-nickel thermocouples on the substrate surface during deposition. The optimal deposition temperatures were found to be lower in comparison with films deposited on LaA1O3 because damage occurs to the buffer layer. For 10 nm thick CeO2 buffer layers, the deposition temperature is limited to a range from about 660 °C to 680 °C. CeO2 deposited at higher temperatures does not act as a barrier to chemical reaction and hence does not produce good YBCO films. The YBCO deposition temperature may be higher than the deposition temperature for CeO2, but is limited to about 800 °C at which point the CeO2 fails. The best results observed were with a deposition temperature of 660 °C for a 10 nm thick CeO2 layer followed by 725°C for a 300 nm thick YBCO layer. Special attention was paid to the occurrence of droplets and outgrowths in the films. The ablation process produces droplets that range from 0. 1 im to a maximum of 1 jim in size. In the course of film growth these droplets undergo metamorphosis and form the basis of outgrowths.

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Section: Methodssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 80%

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<title>Investigation of substrate temperature effect on the surface morphology of excimer laser deposited YBa<formula><inf><roman>2</roman></inf></formula>Cu<formula><inf><roman>3</roman></inf></formula>O<formula><inf><roman>7</roman></inf></formula>/CeO<formula><inf><roman>2</roman></inf></formula> films on sapphire</title>

1994

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“…One of the mechanism of creation of the droplets (usually called outgrowth) can be explained by different growth rates ofYBaCuO in a-b plane and perpendicular to this plane [16]. The other theory suggests that the particles can arise during the expansion of plasma cloud in background gas [17].…”

Section: Droplets Problemmentioning

confidence: 99%

Pulsed Laser Deposition of Thin Films

Jelı́nek

Trtik

Jastrabı́k

1997

Physics and Materials Science of High Temperature Superconductors, IV

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The principle of thin film deposition by laser ablation, a droplet problem, basic schemes for laser deposition of smooth thin films, creation of multilayer structures with YBaCuO, ferroelectric:films and metals are discussed. Experimental results with deposition of YBaCuO on monocrystalline and polycrystalline substrates, buffer layers, ferroelectric films (pZT, PLZT, PMN) and some possible applications are presented.

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“…Standard deposition parameters were used. These parameters were optimised for the growth of epitaxial films with thicknesses between 60 and 200 nm, yielding reproducibly critical temperatures above 87 K [28 ]. After film deposition, silver contacts are evaporated and contact leads are defined by conventional photolithography and argon plasma etching, at a pressure of 4 Pa and a plasma bias voltage of 600 V. For these conditions, the etching rate of YBa2Cu307_6 is approximately 9 nm/min.…”

Section: Preparationmentioning

confidence: 99%

Coherent vortex motion in YBa2Cu3O7-δ nanobridges prepared by a substrate-etching technique

Nivelle

Gerritsma

Rogalla

1994

Physica C: Superconductivity

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Nanobridges with widths down to 140 nm and lengths of about 250 nm were structured in a 25 nm YBa2CuaOT_a thin film, by means of a substrate-etching technique. At low temperatures, the current-voltage characteristics of these bridges show clear signs of periodic single-vortex motion. A quantitative comparison could be made with a vortex-flow model, which describes the forces acting on the vortices inside a hyperbolically shaped nanobridge, with dimensions much smaller than the thin film magnetic-penetration depth. It follows that the related viscous drag coefficient ~/is approximately I. 0 × 10-to kg/ms and the penetration depth is approximately 4 ttm. These values indicate that the transport properties are dominated by the weak-link behaviour of grain boundaries or twin boundaries in the thin film.

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DROPLETS AND OUTGROWTHS ON HIGH-Tc LASER ABLATED THIN FILMS

Cited by 5 publications

References 8 publications

Pulsed Laser Deposition of Thin Films

Coherent vortex motion in YBa2Cu3O7-δ nanobridges prepared by a substrate-etching technique

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