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All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Growth and characterization of epitaxial SrF2 on InP(100)

The epitaxial growth of 100-262.5-nm SrF2 films on n-type and p-type (100)InP in a conventional baked UHV system at base pressure about 200 ptorr, temperature 250-350 C, and growth rate from less than 100 to about 200 pm/s. Substrates are chemicomechanically polished, degreased, bombarded with 500-eV Ar ions for 3-4 min at 350 C, and annealed for 23-30 min at 350 C, producing a slightly In-rich (In/P = 1.02) In-island-free surface with a (4 x 1) or (1 x 1) LEED structure. Films grown at 350 C and less than 100 pm/s are found to be smooth and free of cracks in most cases, with a highly faceted (1 x 1) LEED structure. The electrical properties of the SrF2 films are found to be acceptable only when the ohmic contacts are applied prior to the substrate prior to SrF2 growth.

Sinharoy, S.↗
DOE OSTI2020

Materials Data on SrF2 by Materials Project

SrF2 is Fluorite structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Sr2+ is bonded in a body-centered cubic geometry to eight equivalent F1- atoms. All Sr–F bond lengths are 2.54 Å. F1- is bonded to four equivalent Sr2+ atoms to form a mixture of edge and corner-sharing FSr4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrF2 by Materials Project

SrF2 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Sr2+ is bonded in a 3-coordinate geometry to eleven F1- atoms. There are a spread of Sr–F bond distances ranging from 2.40–2.94 Å. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded to six equivalent Sr2+ atoms to form distorted FSr6 octahedra that share corners with twelve equivalent FSr6 octahedra, corners with twelve equivalent FSr5 trigonal bipyramids, edges with six equivalent FSr6 octahedra, faces with two equivalent FSr6 octahedra, and faces with six equivalent FSr5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 50°. In the second F1- site, F1- is bonded to five equivalent Sr2+ atoms to form distorted FSr5 trigonal bipyramids that share corners with twelve equivalent FSr6 octahedra, corners with eight equivalent FSr5 trigonal bipyramids, edges with six equivalent FSr5 trigonal bipyramids, and faces with six equivalent FSr6 octahedra. The corner-sharing octahedra tilt angles range from 31–59°.

36 MATERIALS SCIENCE↗