Depth profiling of thin films of Ag and Au on Mo deposited on a quartz crystal microbalance

Abstract

Depth profiling of thin films on a quartz crystal microbalance (QCM) is performed by combining the frequency-change rate with two surface sensitive spectroscopies, ion surface scattering (ISS) and Auger electron spectroscopy (AES). The deposition of the thin film on top of the Mo overlayer on the QCM and the composition analyses are carried out in the same uhv-system. One outcome of the method is determination of the variation in the sputtering yield as a function of varying surface composition. For the Au/Mo interface a linear relation is found between sputtering yield and adsorbate concentration. A simple model predicts the linearity. However, profiling of a thin film of Ag on Mo shows deviation from the linear concentration dependence when the adsorbate is much diluted into the substrate.