X-ray fluorescence method for determining the mass absorption coefficient in two-layer thin-film Ti/Ge and Ni/Ge systems

Abstract

We propose a new method for determining the mass absorption coefficient in x-ray fluorescence analysis of two-layer thin-film Ti/Ge and Ni/Ge systems using easily made standardized film layers obtained by deposition of titanium or nickel on a polymer film substrate. We calculate correction factors taking into account absorption of primary emission from the x-ray tube and absorption of the analytical line for an element of the bottom layer in the top layer.Introduction. During synthesis and use of thin-film structures, analytical monitoring is required since most of their properties of practical importance depend on the composition and thickness of the film composites. The problem is complex because in determining the analyte parameters, we need to ensure sufficiently high accuracy under conditions such that the composition and structure are preserved. Among the familiar physicochemical methods for determining both the composition and thickness of each layer in thin-film systems, x-ray fluorescence analysis (XFA) is the most effective. The role and importance of XFA are due to its advantages, including the possibility of carrying out the analysis without destroying the analyte sample, its speed, its multielement capability, and its relatively high accuracy.The major difficulty limiting use of this method for analysis of film structures is the lack of a specific standard set of film layers, needed for determining the mass absorption coefficients. The accuracy of the calculation of these coefficients has a considerable effect on the uncertainty in determination of both the elemental concentrations and the thickness of the layers in the analyte systems. Thus the comparison of the mass attenuation coefficients carried out in [1] using the nine most complete sources showed that there is a significant spread in the data, especially in the case of light elements.Previously, in studying two-layer composites, we used both single-component monolayer and two-layer films [2] and also two-layer systems in which one layer was multicomponent and the other was single-component [3,4]. In calculating the mass absorption coefficients, taking into account attenuation of the primary emission from the x-ray tube and attenuation of the analytical lines for the elements of the bottom layer in the top layer, we used a very labor-intensive method involving deposition of a second layer on the monolayer single-component films. The two-layer systems obtained in this case could not be used later in studying other structures.In this work, in determining the mass absorption coefficient for x-ray fluorescence of Ge in the top layer consisting of Ti or Ni, we propose using easily made standardized monolayer and single-component layers obtained by sputter deposition of the elements on a polymer film substrate [(C 10 H 8 O 4 ) n ]. A certain combination of Ge layers on Polikor and Ti or Ni, sputter deposited on the polymer film and then placed in a special holder, lets us form composites of two-layer film structures identical to the systems to be an...

Determination of the Mass Absorption Coefficient in Two-Layer Ti/V and V/Ti Thin Film Systems by the X-Ray Fluorescence Method

“…In determining mass absorption coeffi cients taking into account attenuation of the primary radiation of the X-ray tube and attenuation of spectral lines of the lower layer elements in the upper layer, a very time-consuming technique was used which entailed applying a second layer onto one-layer single-component fi lms. The resulting two-layer systems could not be used further in the study of other structures.Application of the simple to manufacture unifi ed one-layer single-component layers, obtained by deposition of elements on a polymer fi lm substrate [(C 10 H 8 O 4 ) n ], is proposed here for the determination of the mass absorption coeffi cients of X-ray fl uorescence of Ge atoms (lower layer) for Ti, Ni, V, or Cr (upper layer) found in two-layer systems on polycore substrates [5,6]. Combination of Ge layers on the polycore and Ti, Ni, V, or Cr deposited on a polymer fi lm, when arranged in a particular way, allowed to form composites identical to the systems of two-layer fi lm structures subject to analysis.…”

“…Application of the simple to manufacture unifi ed one-layer single-component layers, obtained by deposition of elements on a polymer fi lm substrate [(C 10 H 8 O 4 ) n ], is proposed here for the determination of the mass absorption coeffi cients of X-ray fl uorescence of Ge atoms (lower layer) for Ti, Ni, V, or Cr (upper layer) found in two-layer systems on polycore substrates [5,6]. Combination of Ge layers on the polycore and Ti, Ni, V, or Cr deposited on a polymer fi lm, when arranged in a particular way, allowed to form composites identical to the systems of two-layer fi lm structures subject to analysis.…”

“…In the auxiliary systems, thin layers of titanium and vanadium (<350 nm) were applied to a polymer fi lm with a thickness of 5 microns. Titanium fi lms were obtained by ion-plasma sputtering in a vacuum [5] on the URM-3.279.026 unit, vanadium fi lms -by electron beam evaporation using a photometric thickness monitoring system [6] on a commercial vacuum unit VU-1A. The pressure of the residual atmosphere before sputtering was 2·10 -4 Pa. A preliminary degassing of the substrates before sputtering was carried out at a temperature of 160 ± 5 o C. The starting materials were target cells of the investigated elements (at least 99.9% pure) in the form of bulk samples that were used later for determining the relative intensities 0 A A I I ∞ .…”