Open AccessIntegration method for directly analyzing interface statistics of periodic multilayers from X‐ray scattering
Author(s) -
Li Haochuan,
Zhu Jingtao,
Wang Zhanshan,
Chen Hong,
Wang Yuzhu,
Wang Jie
Publication year - 2014
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s1600577513024296
Subject(s) - scattering , diagram , exponent , momentum (technical analysis) , surface finish , plane (geometry) , torr , optics , physics , materials science , condensed matter physics , computational physics , geometry , mathematics , statistics , thermodynamics , finance , economics , composite material , linguistics , philosophy
An integration method is demonstrated for directly determining the average interface statistics of periodic multilayers from the X‐ray scattering diagram. By measuring the X‐ray scattering diagram in the out‐of‐plane geometry and integrating the scattered intensity along the vertical momentum transfer q z in an interval, which is decided by the thickness ratio Γ (ratio of sublayer's thickness to periodic thickness), the cross‐correlations between different interfaces are canceled and only the autocorrelations are reserved. Then the multilayer can be treated as a `single interface' and the average power spectral density can be obtained without assuming any vertical correlation model. This method has been employed to study the interface morphology of sputter‐deposited W/Si multilayers grown at an Ar pressure of 1–7 mTorr. The results show an increase in vertical correlation length and a decrease in lateral correlation length with increased Ar pressure. The static roughness exponent α = 0 and dynamic growth exponent z = 2 indicate the Edwards–Wilkinson growth model at an Ar pressure of 1–5 mTorr. At an Ar pressure of 7 mTorr, α = 0.35 and z = 1.65 indicate the Kardar–Parisi–Zhang growth model.