After successful applications of depth profiling with sample rotation
in AES and SIMS we used this technique in XPS, too. Until now, most of
the experimental work with rotational depth profiling has been done b
y AES. It was conclusively shown that the technique enables high depth
resolution which is independent of sputtered depth due to reduced ion
-beam-induced topography effects. AES and XPS differ in some instrumen
tal details and experimental conditions, however, the most important d
ifference with respect to profiling is that of the analysed area, whic
h is, even in the case of small-spot XPS instruments, much larger than
in AES. This results in a decisive distortional influence of crater-e
dge effects on XPS depth profiles obtained on stationary and/or rotate
d samples, and is recognized in an increasing degradation of depth res
olution with sputtered depth. The importance of alignment of the probe
beam, analysed spot, ion beam and rotation axis is discussed and is d
emonstrated by comparison of the results of rotational depth profiling
of a Ni/Cr multilayer structure with AES and XPS.