Depth Profiling Analysis Of Films Research Articles

Radiofrequency GDOES: a powerful technique for depth profiling analysis of thin films

AbstractPreviously, glow discharge optical emission spectroscopy (GDOES), both d.c. and r.f. has been used for depth profiling analysis of thick films several tens of microns thick, utilizing its high sputtering rates of >1 µm min−1. Through selected examples, it is demonstrated here that r.f. GDOES also has enormous potential for depth profiling analysis of ultrathin films <10 nm thick, where AES and SIMS have dominant roles. The significant features of r.f. GDOES enabling such analysis arise from the nature of r.f. glow discharge sputtering where samples, both conducting and non‐conducting, are sputtered very stably with Ar+ ions of low energies (<50 eV) and high current fluxes (of the order of 100 mA cm−2). The low Ar+ energy ensures that film sputtering proceeds without significant formation of altered layers, which is a prerequisite for successful depth profiling analysis of ultrathin films at high depth resolution. The high current fluxes allow sputtering to proceed at very high rates of >1 µm min−1, thereby extending the limit of film thickness for analysis to 100 µm. Thus r.f. GDOES, with its unique ability to accommodate depth profiling analysis of films of a very wide thickness range, is expected to play an important role in the field of practical surface analysis. Copyright © 2003 John Wiley & Sons, Ltd.

Non-uniform sputtering and degradation of depth resolution during GDOES depth profiling analysis of thin anodic alumina films grown over rough substrates

Degradation of depth resolution during glow discharge optical emission spectroscopy (GDOES) depth profiling analysis of thin films, formed on relatively rough substrates, has been investigated using preconditioned aluminium substrates of controlled surface roughness. The anodic alumina films, -120 nm thick, were depth profiled partially and examined carefully by atomic force microscopy and by transmission electron microscopy of ultramicrotomed sections. It is revealed clearly that depth profiling sputters ridges, associated with the rough surface, more rapidly than valleys, thereby degrading depth resolution. Further, such observations show that film sputtering proceeds very smoothly, with relatively little damage to the remaining film material. The excellent depth resolution realized during GDOES depth profiling analysis of films grown on mirror-finished, microscopically flat substrates is clearly associated with the highly uniform sputtering of amorphous anodic alumina.

Electrochemical and surface analytical study of the formation of oxide films on monel-400 and copper in alkaline media

The nature of the oxide films formed on monel-400 and copper in presence of NaOH and N-methylpyrrolidine (a volatile amine) at pH 9.5 and in 0.1 M KNO3 medium were investigated. The oxide films were grown by applying an anodic potential of +0.4 V (vs saturated calomel electrode) for 30 min. The compositions of the surface oxide films were analysed by X-ray photoelectron spectroscopy. In the case of copper in NaOH medium, Cu(0) and a very small amount of copper hydroxide were observed. However, in amine medium, Cu(0) and Cu-amine complex were found. For monel in NaOH, the anodic film was found to contain hydroxides of both copper and nickel. After sputtering, this film showed a small amount of metal oxide below the hydroxide layer as confirmed by the oxygen peak. In amine medium the anodic film was found to contain only nickel hydroxide and metallic copper. The depth profile analysis of films showed that the film developed was very thin and the nickel hydroxide was sputtered very easily from the film.