Reaction paths and kinetics of aluminide formation in Al/epitaxial-W(001) model diffusion barrier systems
Single‐crystal bcc W(001) layers, 140 nm thick, were grown on MgO(001) substrates by ultrahigh‐vacuum (UHV) magnetron sputter deposition at Ts=600 °C. Al overlayers, 190 nm thick with strong (001) and (011) preferred orientation and an average grain size of 200 nm, were then deposited at Ts=100 °C without breaking vacuum. Changes in bilayer sheet resistance Rs were monitored continuously as a function of time ta and temperature Ta during UHV annealing. In addition, Rutherford backscattering spectroscopy, x‐ray diffraction, transmission electron microscopy (TEM), and scanning TEM, in which cross‐sectional specimens were analyzed by energy‐dispersive x‐ray analysis with a 1 nm resolution, were used to follow area‐averaged and local interfacial reaction paths as well as microstructural changes as a function of annealing conditions. The initial reaction products were discontinuous regions of monoclinic‐structure WAl4 which exhibit a crystallographic relationship with the underlying W layer. bcc WAl12 forms at...
Marker barrier effect in diffusion species study of Ni/Al and W/Al reactions
Rutherford backscattering spectrometry, X-ray diffraction and scanning electron microscopy were used to study the marker barrier effect in the thermally induced thin film reactions of W/(Ni marker)/Al and Ni/(W marker)/Al structures. The nickel marker did not have a barrier effect in the W/Al reaction, but the tungsten marker did in the Ni/Al reaction. The occurrence of the marker barrier effect is decided by the reaction starting temperatures of aluminum with tungsten and nickel.
Liquid state 1H high field NMR in food analysis.
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