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Silicon nitride transmission X-ray mirrors.

Cornaby S, Bilderback DH - J Synchrotron Radiat (2008)

Bottom Line: Transmission X-ray mirrors have been fabricated from 300-400 nm-thick low-stress silicon nitride windows of size 0.6 mm x 85 mm.The energy cut-off can be adjusted from 8 to 12 keV at an angle of 0.26 degrees to 0.18 degrees , respectively.The observed mirror transmittance was above 80% for a 300 nm-thick film.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA.

ABSTRACT
Transmission X-ray mirrors have been fabricated from 300-400 nm-thick low-stress silicon nitride windows of size 0.6 mm x 85 mm. The windows act as a high-pass energy filter at grazing incidence in an X-ray beam for the beam transmitted through the window. The energy cut-off can be selected by adjusting the incidence angle of the transmission mirror, because the energy cut-off is a function of the angle of the window with respect to the beam. With the transmission mirror at the target angle of 0.22 degrees , a 0.3 mm x 0.3 mm X-ray beam was allowed to pass through the mirror with a cut-off energy of 10 keV at the Cornell High Energy Synchrotron Source. The energy cut-off can be adjusted from 8 to 12 keV at an angle of 0.26 degrees to 0.18 degrees , respectively. The observed mirror transmittance was above 80% for a 300 nm-thick film.

No MeSH data available.


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Drawing of silicon nitride TM windows on a silicon wafer. The upper support blocks the reflected beam.
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fig1: Drawing of silicon nitride TM windows on a silicon wafer. The upper support blocks the reflected beam.

Mentions: The films for the windows were grown by vapour deposition on silicon double-sided polished 100 mm-diameter wafers. The films grown on the wafers had thicknesses of 300 nm and had a uniform thickness of within 2–5% over the entire wafer, with the thickness in the middle of the wafer being slightly thinner than the thickness at the edges. The roughness of typical silicon nitride films is 1.5 nm r.m.s. to well over 2 nm, measured by atomic force microscopy at the Cornell Nano­Scale Science and Technology Facility (R. Ilic, personal communication). Our films have not been measured by atomic force microscopy to verify their roughness. Each wafer had three windows of size 0.6 mm × 85 mm. One of the 0.6 mm sides was not supported by the silicon wafer in order to allow the transmitted beam to pass through. Thus, a piece of silicon wafer covered by silicon nitride was glued onto the top side of the silicon wafer with epoxy to support the free side of the silicon nitride window (Fig. 1 ▶). This unfortunately blocks the reflected beam from the transmission window. Other support methods have been tested to allow collection of both the transmitted and reflected beams from the silicon nitride membrane, but they have not yet produced a working TM.


Silicon nitride transmission X-ray mirrors.

Cornaby S, Bilderback DH - J Synchrotron Radiat (2008)

Drawing of silicon nitride TM windows on a silicon wafer. The upper support blocks the reflected beam.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2631103&req=5

fig1: Drawing of silicon nitride TM windows on a silicon wafer. The upper support blocks the reflected beam.
Mentions: The films for the windows were grown by vapour deposition on silicon double-sided polished 100 mm-diameter wafers. The films grown on the wafers had thicknesses of 300 nm and had a uniform thickness of within 2–5% over the entire wafer, with the thickness in the middle of the wafer being slightly thinner than the thickness at the edges. The roughness of typical silicon nitride films is 1.5 nm r.m.s. to well over 2 nm, measured by atomic force microscopy at the Cornell Nano­Scale Science and Technology Facility (R. Ilic, personal communication). Our films have not been measured by atomic force microscopy to verify their roughness. Each wafer had three windows of size 0.6 mm × 85 mm. One of the 0.6 mm sides was not supported by the silicon wafer in order to allow the transmitted beam to pass through. Thus, a piece of silicon wafer covered by silicon nitride was glued onto the top side of the silicon wafer with epoxy to support the free side of the silicon nitride window (Fig. 1 ▶). This unfortunately blocks the reflected beam from the transmission window. Other support methods have been tested to allow collection of both the transmitted and reflected beams from the silicon nitride membrane, but they have not yet produced a working TM.

Bottom Line: Transmission X-ray mirrors have been fabricated from 300-400 nm-thick low-stress silicon nitride windows of size 0.6 mm x 85 mm.The energy cut-off can be adjusted from 8 to 12 keV at an angle of 0.26 degrees to 0.18 degrees , respectively.The observed mirror transmittance was above 80% for a 300 nm-thick film.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA.

ABSTRACT
Transmission X-ray mirrors have been fabricated from 300-400 nm-thick low-stress silicon nitride windows of size 0.6 mm x 85 mm. The windows act as a high-pass energy filter at grazing incidence in an X-ray beam for the beam transmitted through the window. The energy cut-off can be selected by adjusting the incidence angle of the transmission mirror, because the energy cut-off is a function of the angle of the window with respect to the beam. With the transmission mirror at the target angle of 0.22 degrees , a 0.3 mm x 0.3 mm X-ray beam was allowed to pass through the mirror with a cut-off energy of 10 keV at the Cornell High Energy Synchrotron Source. The energy cut-off can be adjusted from 8 to 12 keV at an angle of 0.26 degrees to 0.18 degrees , respectively. The observed mirror transmittance was above 80% for a 300 nm-thick film.

No MeSH data available.


Related in: MedlinePlus