Keith L. Hart

Thermal Stability of W/C Multilayer Films

W(10A)/C(40A), W(15A)/C(15A) and W(40A)/C(10A) periodic multilayer films were prepared by magnetron sputtering and subsequently annealed at 730°C. The resulting change of the layered and crystal structures was studied by X-ray diffraction. The resulting structures largely depended on the thickness ratio of W to C. For example, in the W(15Å)/C(15Å) sample a-W as formed without any peaks of carbon crystals; in W(40Å) C(10Å)only W2C (orthorhombic) peaks appeared.

Measured X-ray Performance of Synthetic Multilayers Compared To Calculated Effects of Layer Imperfection

In connection with the manufacture of OVONYXTM multilayer x-ray optical elements, investigations have been carried out into the effects of various types of layer imperfections on the x-ray optical properties of multilayers. These have included extensive numerical modeling of real multilayers (using a computational scheme based on the complete dynamical theory) including simulations of interface diffusion, deviations from constant d-spacing, and interface roughness. Results are presented for several examples of Hf-Si and W-Si multilayers, including comparison of measurements at Cu-Kato the theoretical model.

MULTILAYER X-RAY REFLECTORS: EFFECTS OF LAYER IMPERFECTIONS

Periodic multilayer structures, consisting of largely amorphous alternating layers of heavy and light elements, have been fabricated by sputtering techniques. Investigations have been carried out into the effects of various types of layer imperfections on the x-ray optical properties of these multilayers. These have included extensive numerical modeling of real multilayers (using a computational scheme based on the complete dynamical theory) with simulations of diffused interfaces and deviations from constant d-spacing. Results are presented for examples of W–C and Hf–Si multilayers, with comparison of measurements at Cu–K to the theoretical model.