The combination of time‐of‐flight secondary mass spectrometry (ToF‐SIMS) and monochromatized x‐ray photoelectron spectroscopy (XPS) has proved to be a valuable tool for the analysis of chemically modified polymer surfaces. By applying these techniques in situ, together with a plasma modification chamber and a Knudsen cell, we have investigated the plasma modification of polyimide in an oxygen plasma and the first steps of copper deposition on the untreated and the plasma‐modified polyimide substrate. Characterization of the initial stages of copper deposition by XPS and comparison with the untreated and the plasma‐modified substrate indicate that, in the case of the untreated substrate, copper binds to the carbonyl group of the repeat unit, whereas after plasma modification a great number of C–O and C–N functionalities are available as binding sites for the metal overlayer. The molecular ion species identified by ToF‐SIMS allow the identification of specific plasma‐induced fragmentation mechanisms and confirm the interface reaction mechanisms deduced from the XPS results. The nature and amount of copper–substrate bonds are directly correlated to the adhesion strength of the copper/polyimide interface as measured by the force applied in a standard industrial peel test. Copyright © 1999 John Wiley & Sons, Ltd.

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AlGaN/GaN-based high electron mobility transistor heterostructures with different GaN cap layer thicknesses were grown by metalorganic vapor phase epitaxy (MOVPE) and molecular beam epitaxy. The influence of the different growth methods on the structure of the GaN caps was examined by x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Due to the high surface sensitivity of these methods, several effects, such as residual Al incorporation into the GaN cap during growth, etching of the GaN cap during cool-down, and preferential etching of Ga out of the AlGaN barrier could be evaluated. It is demonstrated that these effects play a major role for MOVPE-grown structures

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