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Epitaxial beryllium films and beryllium-based multilayer mirrors for soft x-rays

Thesis/Dissertation ·
OSTI ID:121185

Epitaxial Be films and Be-based multilayers were fabricated and characterized for a variety of deposition conditions. Epitaxial Be films were grown for the first time on {alpha}-Al{sub 2}O{sub 3} (0001), Si (111), Si(100), GaAs (111), and Ge (111) single-crystal substrates. The effects of the substrate material, substrate temperature, deposition rate, and post-annealing temperature on the crystalline quality of the epitaxial Be films were studied. All of the resultant epitaxial films exhibited the hexagonal close-packed (hcp) Be crystal structure. Epitaxial Be films which were grown on substrates with hexagonal lattices [{alpha}-Al{sub 2}O{sub 3} (0001), Si (111), and Ge (111)] invariably grew with their hexaganal lattices parallel to the substrate plane. In nearly all cases, the Be hcp lattice grew in the anticipated best-fit epitaxial relation with the substrate. The crystalline quality of the Be films improved significantly with increasing substrate temperature. However, Be films deposited at substrate temperatures {>=}400{degrees}C were discontinuous, and many exhibited hexagonal-shaped crystallites. The deposition rate had no effect on crystalline quality over the range studied (3.1-18.5 {angstrom}/min). Annealing epitaxial Be films at temperatures {<=}625{degrees}C after deposition improved crystalline quality only slightly. Annealing the films at 700{degrees}C resulted in the collapse of hexagonal grains in order to relieve stress within the film.

Research Organization:
Arizona Univ., Tucson, AZ (United States)
OSTI ID:
121185
Country of Publication:
United States
Language:
English