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Title: Bombardment-Induced Tunable Superlattices in the Growth of Au-Ni Films

Abstract

Highly ordered superlattices are typically created through the sequential deposition of two different materials. Here, we report our experimental observation of spontaneous formation of superlattices in coevaporation of Au and Ni under energetic ion bombardment. The superlattice periodicities are on the order of a few nanometers and can be adjusted through the energy and flux of ion beams. Such a self-organization process is a consequence of the bombardment-induced segregation and uphill diffusion within the advancing nanoscale subsurface zone in the film growth. Our observations suggest that ion beams can be employed to make tunable natural superlattices in the deposition of phase-separated systems with strong bombardment-induced segregation.

Authors:
; ; ; ;  [1]
  1. Naval Research Laboratory, Washington, DC 20375 (United States)
Publication Date:
OSTI Identifier:
20778601
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 96; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevLett.96.056105; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRYSTAL GROWTH; DEPOSITION; GOLD; ION BEAMS; NANOSTRUCTURES; NICKEL; PERIODICITY; SEGREGATION; SUPERLATTICES; TAIL IONS; THIN FILMS

Citation Formats

He, J.H., Carosella, C.A., Hubler, G.K., Qadri, S.B., and Sprague, J.A.. Bombardment-Induced Tunable Superlattices in the Growth of Au-Ni Films. United States: N. p., 2006. Web. doi:10.1103/PHYSREVLETT.96.0.
He, J.H., Carosella, C.A., Hubler, G.K., Qadri, S.B., & Sprague, J.A.. Bombardment-Induced Tunable Superlattices in the Growth of Au-Ni Films. United States. doi:10.1103/PHYSREVLETT.96.0.
He, J.H., Carosella, C.A., Hubler, G.K., Qadri, S.B., and Sprague, J.A.. Fri . "Bombardment-Induced Tunable Superlattices in the Growth of Au-Ni Films". United States. doi:10.1103/PHYSREVLETT.96.0.
@article{osti_20778601,
title = {Bombardment-Induced Tunable Superlattices in the Growth of Au-Ni Films},
author = {He, J.H. and Carosella, C.A. and Hubler, G.K. and Qadri, S.B. and Sprague, J.A.},
abstractNote = {Highly ordered superlattices are typically created through the sequential deposition of two different materials. Here, we report our experimental observation of spontaneous formation of superlattices in coevaporation of Au and Ni under energetic ion bombardment. The superlattice periodicities are on the order of a few nanometers and can be adjusted through the energy and flux of ion beams. Such a self-organization process is a consequence of the bombardment-induced segregation and uphill diffusion within the advancing nanoscale subsurface zone in the film growth. Our observations suggest that ion beams can be employed to make tunable natural superlattices in the deposition of phase-separated systems with strong bombardment-induced segregation.},
doi = {10.1103/PHYSREVLETT.96.0},
journal = {Physical Review Letters},
number = 5,
volume = 96,
place = {United States},
year = {Fri Feb 10 00:00:00 EST 2006},
month = {Fri Feb 10 00:00:00 EST 2006}
}
  • A technique is described for selectively modifying, by ion bombardment during film growth, the state of internal stress of thin films on flexible polymer substrates. A laser-monitoring system is used to measure strain-induced deflections of the simply supported substrate prior to, during, and after the deposition without disturbing the film--substrate system. Sensitivity of the in situ measured bending force per unit width is approx.130 dyn/cm. The result is a composite view of the ''frozen-in'' thin-film internal stress including postdeposition relaxation. Permalloy (83% Ni--17% Fe) is deposited on Kapton at room temperature by electron beam evaporation simultaneous with Ar/sup +/ bombardmentmore » of current densities j = 10 to 1000 ..mu..A/cm/sup 2/ and ion energies E = 150, 300, 750, and 1500 eV/ion. In the absence of ion bombardment, the average internal stress is tensile with a value of 11 Gdyn/cm/sup 2/ for deposition rate = 0.5 nm/s. Transition from tensile to compressive stress is a strong function of j and a rather weak function of E.« less
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  • The structure of sputtered Mo/Fe superlattices of periodicities 9 to 30 A grown at a substrate temperature of 300 K at various pressures and levels of low-energy ion bombardment have been studied using x-ray diffraction. The samples show the growth of an amorphous phase below 17 A periodicity and a crystalline phase above 21 A, with mixed phases in between. Limited ion bombardment reduces the coherency in the growth direction in the crystalline phase, while heavy bombardment sufficient to promote significant mixing acts to improve the coherency, but not to the level observed in films with no bombardment. The relativemore » intensities of the average lattice spacing reflection and its most intense satellite give the composition profile change due to the ion mixing. Some ion bombardment of the iron layer markedly improves the reflectance for x rays at both low and high angles near the Bragg peak due to the average lattice spacing.« less
  • No abstract prepared.