Authors: Shaaker Hajati Sven Tougaard
Publish Date: 2010/01/21
Volume: 396, Issue: 8, Pages: 2741-2755
Abstract
Depth profiling of nanostructures is of high importance both technologically and fundamentally Therefore many different methods have been developed for determination of the depth distribution of atoms for example ion beam eg O 2 + Ar+ sputtering lowdamage C60 cluster ion sputtering for depth profiling of organic materials water droplet cluster ion beam depth profiling ionprobing techniques Rutherford backscattering spectroscopy RBS secondaryion mass spectroscopy SIMS and glowdischarge optical emission spectroscopy GDOES Xray microanalysis using the electron probe variation technique combined with Monte Carlo calculations angleresolved XPS ARXPS and Xray photoelectron spectroscopy XPS peakshape analysis Each of the depth profiling techniques has its own advantages and disadvantages However in many cases nondestructive techniques are preferred these include ARXPS and XPS peakshape analysis The former together with parallel factor analysis is suitable for giving an overall understanding of chemistry and morphology with depth It works very well for flat surfaces but it fails for rough or nanostructured surfaces because of the shadowing effect In the latter method shadowing effects can be avoided because only a single spectrum is used in the analysis and this may be taken at near normal emission angle It is a rather robust means of determining atom depth distributions on the nanoscale both for largearea XPS analysis and for imaging We critically discuss some of the techniques mentioned above and show that both ARXPS imaging and particularly XPS peakshape analysis for 3D imaging of nanostructures are very promising techniques and open a gateway for visualizing nanostructures
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