Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Feedstock verification of silicon boules for SRM640g
Comparison of the left-beam and right-beam diffraction patterns from float-zone silicon. The central peak offset is related to the lattice spacing difference from the transfer crystal. The horizontal scale is in raw angle-interferometer fringes, where 1 fringe is roughly 0.775 μrad (0.16 second of arc). The instrumental angular resolution is approximately 1 nrad.
The incoming intrinsic float-zone silicon boules which will become SRM640g were verified for quality by measuring their lattice spacing. The ability to make such a measurement assured the original crystal is nearly perfect, with very low strain and defect density. The sharp, central fringe in the image will not appear on a crystal with significant imperfections.