Reflectance measurements on clean surfaces for the determination of optical constants of silicon in the EUV/soft-x-ray range
- Univ. of California, Berkeley, CA (United States); Ernest Orlando Lawrence Berkeley National Lab., CA (United States). Center for X-ray Optics
- Ernest Orlando Lawrence Berkeley National Lab., CA (United States). Center for X-ray Optics
The response of a given material to an incident electromagnetic wave is described by the energy dependent complex index of refraction n = 1 {minus} {delta} + i{beta}. In the extreme ultraviolet (EUV)/ soft x-ray spectral region, the need for accurate determination of n is driven by activity in areas such as synchrotron based research, EUV/x-ray lithography, x-ray astronomy and plasma applications. Various methods are used in order to determine the optical constants {delta}, {beta} such as reflectance measurements, angle dependent electron yield, transmission measurements, interferometry and ellipsometry. In this work, the method of angle dependent reflectance is evaluated and implemented in order to obtain the optical constants of Si in the region around the L{sub 2,3} edge (99.8 eV). Silicon is among the materials of particular importance for practical applications in the EUV/soft x-ray range, due to its implementation as filter and spacer material in multilayer mirrors, for energies below the L{sub 2,3} edge. The refractive index of Si in this energy range has been investigated by previous experimenters using various methods. The discrepancies among their data arise mainly due to the surface quality of the samples used for measurements and the inherent difficulties of each method. Angle dependent reflectance measurements have the advantage that both {delta} and {beta} may be deduced experimentally, and thus provide an important test of the tabulated values of {delta} generated using the Kramers-Kronig relations. In addition, measurements may be performed on bulk samples without the need to fabricate the free standing thin films required for transmission measurements.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 603484
- Report Number(s):
- LBNL-39981; ON: DE97007345; TRN: 98:009512
- Resource Relation:
- Related Information: Is Part Of: Advanced light source: Compendium of user abstracts 1993--1996, 622 p.
- Country of Publication:
- United States
- Language:
- English
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