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Journal ArticleDOI

Kinetic-energy induced smoothening and delay of epitaxial breakdown in pulsed-laser deposition

24 Aug 2007-Physical Review B (American Physical Society)-Vol. 76, Iss: 8, pp 085431
TL;DR: In this paper, the effect of kinetic energy of depositing species from flux pulsing during pulsed-laser deposition (PLD) on surface morphology evolution of Ge(001) homoepitaxy at low temperature was isolated.
Abstract: We have isolated the effect of kinetic energy of depositing species from the effect of flux pulsing during pulsed-laser deposition (PLD) on surface morphology evolution of Ge(001) homoepitaxy at low temperature $(100\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C})$. Using a dual molecular beam epitaxy (MBE) PLD chamber, we compare morphology evolution from three different growth methods under identical experimental conditions except for the differing nature of the depositing flux: (a) PLD with average kinetic energy $300\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ (PLD-KE); (b) PLD with suppressed kinetic energy comparable to thermal evaporation energy (PLD-TH); and (c) MBE. The thicknesses at which epitaxial breakdown occurs are ranked in the order $\mathrm{PLD}\text{\ensuremath{-}}\mathrm{KE}g\mathrm{MBE}g\mathrm{PLD}\text{\ensuremath{-}}\mathrm{TH}$; additionally, the surface is smoother in PLD-KE than in MBE. The surface roughness of the films grown by PLD-TH cannot be compared due to the early epitaxial breakdown. These results demonstrate convincingly that kinetic energy is more important than flux pulsing in the enhancement of epitaxial growth, i.e., the reduction in roughness and the delay of epitaxial breakdown.

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Citations
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Proceedings ArticleDOI
21 Jul 2020
TL;DR: In this paper, the authors used time-domain thermoreflectance to measure the thermal conductivity and thermal boundary conductance (TBC) of thin films of β-Ga 2 O 3 grown using molecular beam epitaxy (MBE) on c-Al 2O 3 (sapphire) and 4H-SiC substrates.
Abstract: β-Ga 2 O 3 is considered as a promising material for future power electronic applications. In this work, we used time-domain thermoreflectance to measure the thermal conductivity and thermal boundary conductance (TBC) of thin films of β-Ga 2 O 3 grown using molecular beam epitaxy (MBE) on c-Al 2 O 3 (sapphire) and 4H-SiC substrates. One sample was 119 nm thick on sapphire, while the other sample was 81 nm thick on 4H-SiC. The Ga 2 O 3 layer on c-sapphire presented a through-plane thermal conductivity of 3.2 ± 0.3 W/m-K with a Ga 2 O 3 /sapphire TBC of 155.6 ± 65.3 MW/m2-K. The thermal conductivity of the Ga 2 O 3 layer on 4H-SiC was measured as 3.1 ± 0.5 W/m-K with a Ga 2 O 3 /SiC TBC of 141.8 ± 63.8 MW/m2-K. When compared with the thermal conductivity of films grown using pulsed-laser deposition from a previous study, thermal conductivity of layers grown by MBE show higher values, which suggests that the films grown by epitaxial method such as MBE can improve the thermal conductivity of thin films.

2 citations


Additional excerpts

  • ...example, researchers in [24] compared the low temperature...

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Book ChapterDOI
01 Jan 2011
TL;DR: In this paper, the authors analyzed the interlayer transport as the primary driving force behind formation of atomically sharp layers from the measurements of time constants and shot-to-shot changes in single laser shot time dependent coverages in the growth of perovskite srTiO3.
Abstract: We review recent results in the study of pulsed laser deposition growth kinetics using real-time surface X-ray diffraction. interlayer transport as the primary driving force behind formation of atomically sharp layers is analyzed quantitatively from the measurements of time constants and shot-to-shot changes in single laser shot time dependent coverages in the growth of the model perovskite srTiO3. The results show that direct deposition into the open layers and very fast interlayer transport driven by energetic species during the arrival of the laser plume are the main components of layer growth per laser shot in both homo-and heteroepitaxy of complex oxides.

2 citations

Journal ArticleDOI
TL;DR: In this article, the growth of strongly textured thin films on substrates was achieved with ultrashort-pulsed laser deposition using 810-nm, 46-fs ablation pulses.
Abstract: Growth of strongly textured $\mathrm{FeCO}_{3}$ thin films on substrates was achieved with ultrashort-pulsed laser deposition using 810-nm, 46-fs ablation pulses. The crystallinity and composition were verified with X-ray diffraction and Raman spectroscopy. Using Mossbauer spectroscopy, it is shown that the deposited $\mathrm{FeCO}_{3}$ thin films possess the film quality required for application in research of nuclear quantum optics. It is found that a relatively low substrate temperature is crucial for growing a strongly textured film of $\mathrm{FeCO}_{3}$ while avoiding decomposition of $\mathrm{FeCO}_{3}$ into $\mathrm{Fe}_{2}\mathrm{O}_{3}$ and $\mathrm{CO}_{2}$ . This supports the importance of the use of ultrashort-pulsed laser deposition in providing adatoms with high mobility for attaining good crystallinity. The surface morphology was characterized by surface profilometry, scanning electron microscopy and atomic force microscopy. It is found to be significantly affected by changing the ablation laser parameters, including laser fluence, pulse duration, and on-target spot size. The results show that the peak deposition flux must be below approximately 0.03 nm/pulse in order to grow a flat film.

1 citations

Journal ArticleDOI
TL;DR: In this article, in situ x-ray scattering was used to study homoepitaxy properties of particles with kinetic energies of less than 10 eV for both energetic deposition and thermalization by He background gas.
Abstract: Pulsed laser deposition (PLD) is widely used to grow epitaxial thin films of quantum materials. Here, we use in situ x-ray scattering to study homoepitaxy of ${\mathrm{SrTiO}}_{3}$ by energetic deposition (e-PLD) versus PLD thermalized by a He background gas (th-PLD). Energetic PLD suppresses the lateral growth of two-dimensional islands, which suggests that particles with kinetic energies of $\ensuremath{\sim}100$ eV break up smaller islands. Fast interlayer transport occurs for th-PLD as well as e-PLD, implying a process operating on submicrosecond time scales for incident particles with kinetic energies below 10 eV.

1 citations

Journal ArticleDOI
TL;DR: The theoretical fundamentals of a promising growth kinetics of films from the vapor phase are outlined, in which pulsed fluxes are combined with temperature transients to enable short-range surface relaxations and to inhibit long-range relaxations.
Abstract: Here, we outline the theoretical fundamentals of a promising growth kinetics of films from the vapor phase, in which pulsed fluxes are combined with temperature transients to enable short-range surface relaxations (e.g., species rearrangements) and to inhibit long-range relaxations (atomic exchange between species). A group of physical techniques (fully pulsed thermal and/or laser depositions) based on this kinetics is developed that can be used to prepare films with roughnesses even lower than those obtained with pulsed-laser deposition, which is the physical vapor-phase deposition technique that has produced the flattest films reported so far.

1 citations

References
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Book ChapterDOI
01 Jan 1994
TL;DR: Pulsed laser deposition of high-temperature superconducting thin films for active and passive device applications is discussed in this article, with a focus on the commercial scale-up of Pulsed Laser Deposition.
Abstract: Partial table of contents: History and Fundamentals of Pulsed Laser Deposition (J. Cheung). Diagnostics and Characteristics of Laser--Produced Plasmas (D. Geohegan). Particulates Generated by Pulsed Laser Ablation (L.--C. Chen). Angular Distribution of Ablated Material (K. Saenger). Film Nucleation and Film Growth in Pulsed Laser Deposition of Ceramics (J. Horwitz & J. Sprague). Processes Characteristics and Film Properties in Pulsed Laser Plasma Deposition (S. Metev). Commercial Scale--Up of Pulsed Laser Deposition (J. Greer). Pulsed Laser Deposition: Future Trends (T. Venkatesan). Comparison of Vacuum Deposition Techniques (G. Hubler). Pulsed Laser Deposition of High--Temperature Superconducting Thin Films for Active and Passive Device Applications (R. Muenchausen & X. Wu). Pulsed Laser Deposition of Metals (J. Kools). Appendix. References. Index.

3,228 citations

Journal ArticleDOI
TL;DR: In this article, the authors outline the fundamental physics involved and go on to discuss recent experimental findings of pulsed laser deposition, as an alternative to chemical vapor deposition or molecular beam epitaxy.
Abstract: Photons have many advantages for vaporizing condensed systems, and laser vaporization sources have a flexibility not available with other methods. These sources are applied to making thin films in the well-known technique of pulsed laser deposition (PLD). The vaporized material may be further processed through a pulsed secondary gas, lending the source additional degrees of freedom. Such pulsed-gas sources have long been exploited for fundamental studies, and they are very promising for film deposition, as an alternative to chemical vapor deposition or molecular beam epitaxy. The authors outline the fundamental physics involved and go on to discuss recent experimental findings.

722 citations

Journal ArticleDOI
TL;DR: In this paper, the magnetoresistance peak occurs around the Curie point, whereas for x = 0.5 the onset of magnetoreduction is somewhat below and increases monotonically as.
Abstract: Manganites of the series , with x = 0, 0.1, 0.3, 0.5, 0.7 and 1.0, have been characterized in ceramic form and thin films have been prepared by pulsed laser deposition. Characterization techniques included x-ray diffraction, conductivity and magnetoresistance, magnetization and susceptibility, optical spectroscopy and the Faraday effect. Both the films and ceramics exhibit a maximum low-temperature conductivity at which is coexistent with ferromagnetic order. The negative magnetoresistance effect is qualitatively different for the x = 0.3 and x = 0.5 compositions. For x = 0.3 the magnetoresistance peak occurs around the Curie point, whereas for x = 0.5 the onset of magnetoresistance is somewhat below and increases monotonically as . The applied field appears to modify the magnetic order (on the scale of the spin diffusion length) down to the lowest temperatures for x = 0.5, but for x = 0.3 the ferromagnetic order is essentially complete and collinear below the Curie point.

415 citations

Journal ArticleDOI
TL;DR: In this article, the dynamics of nanoparticle formation, transport, and deposition by pulsed laser ablation of c-Si into 1-10 Torr He and Ar gases are revealed by imaging laser-induced photoluminescence and Rayleigh-scattered light from gas-suspended 1−10 nm SiOx particles.
Abstract: The dynamics of nanoparticle formation, transport, and deposition by pulsed laser ablation of c-Si into 1–10 Torr He and Ar gases are revealed by imaging laser-induced photoluminescence and Rayleigh-scattered light from gas-suspended 1–10 nm SiOx particles. Two sets of dynamic phenomena are presented for times up to 15 s after KrF-laser ablation. Ablation of Si into heavier Ar results in a uniform, stationary plume of nanoparticles, while Si ablation into lighter He results in a turbulent ring of particles which propagates forward at 10 m/s. Nanoparticles unambiguously formed in the gas phase were collected on transmission electron microscope grids for Z-contrast imaging and electron energy loss spectroscopy analysis. The effects of gas flow on nanoparticle formation, photoluminescence, and collection are described.

318 citations

Journal ArticleDOI
TL;DR: In this article, the basic principles of nanoparticle synthesis by conventional pulsed laser ablation are described and the theoretical development and analysis of the experimental results are given for condensation, expansion and properties of silicon nanoclusters.

188 citations