Neutron reflectometry study of thermally induced boron diffusion in amorphous elemental boron

Gregory S. Smith; William A. Hamilton; Michael R. Fitzsimmons; Shenda M. Baker; Kevin M. Hubbard; Michael Nastasi; Juhani P. Hirvonen; Thomas G. Zocco

doi:10.1117/12.130635

23 November 1992 Neutron reflectometry study of thermally induced boron diffusion in amorphous elemental boron

Gregory S. Smith, William A. Hamilton, Michael R. Fitzsimmons, Shenda M. Baker, Kevin M. Hubbard, Michael Nastasi, Juhani P. Hirvonen, Thomas G. Zocco

Author Affiliations +

Proceedings Volume 1738, Neutron Optical Devices and Applications; (1992) https://doi.org/10.1117/12.130635
Event: San Diego '92, 1992, San Diego, CA, United States

Abstract

We have begun a series of neutron reflectometry studies to investigate atomic diffusion behavior in both elemental boron and refractory transition-metal borides. In this paper, we report on the results for boron-atom self-diffusion in amorphous elemental boron. The samples used for the measurements were thin-film bilayer structures consisting of alternating layers of isotopically enriched ¹⁰B and ¹¹B, deposited by electron-beam evaporation. The reflectometry studies were performed with a beam of pulsed neutrons having a broad thermal spectrum incident on the samples at an angle of approximately 1.00 degree(s). Specularly reflected neutrons were detected as a function of their time-of-flight with a position-sensitive detector. This data was reduced to obtain a plot of the reflectivity vs. the perpendicular wavevector. Because of the different nuclear potentials for the two boron isotopes, an interference pattern was observed, analogous to those obtained by X-ray measurements on samples with a modulated index of refraction. Reflectivity profiles were measured and analyzed as a function of annealing time for temperatures of 360 degree(s)C and 400 degree(s)C. Variations in the interference patterns were then used to determine the diffusion coefficient, D, at 360 degree(s)C, and hence the intrinsic diffusion parameters. A typical equilibrium result was determined to be D approximately 10^-1 angstroms²s, measured at an annealing temperature of 360 degree(s)C. The measured diffusion constants are inconsistent with the high melting temperature of elemental boron, but are consistent with measured diffusion constants in other amorphous thin films.

Citation Download Citation

Gregory S. Smith, William A. Hamilton, Michael R. Fitzsimmons, Shenda M. Baker, Kevin M. Hubbard, Michael Nastasi, Juhani P. Hirvonen, and Thomas G. Zocco "Neutron reflectometry study of thermally induced boron diffusion in amorphous elemental boron", Proc. SPIE 1738, Neutron Optical Devices and Applications, (23 November 1992); https://doi.org/10.1117/12.130635

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available