Depth profiling energy relation

Q.) is based on the ejection of the recoiled particles out of the sample in the forward direction by an energetic heavy ion beam. The measured energy spectra of these recoiled atoms can be related to their concentration profiles. The use of range foil in front of the energy detector to permit selective absorption of the various recoils introduces a few limitations in the application of the technique, e.g. deterioration of the energy resolution and hence the depth resolution, the limitation on the accessible depth in the depth profile information, etc. Indeed, the practical utility of the experimental set-up is enormously reduced in the region where overlapping spectra of various atoms are difficult to separate. 

The quantity of interest is the elemental concentration as a function of depth. The detected number of events are related to the concentration while their energies with respect to the maximum energy (surface energy) gives the depth information. These are discussed further in the depth profile analysis procedure described later. 

One related protocol that alleviates this problem is low energy (-200 eV) depth profiling with Cs ions [343],... 

In addition, adjustment factors were reported to be required for specific elements whose concentrations were being over estimated, i.e. those of H, C, and O (van der Heide et al. 1998). Subsequent studies carried out under improved vacuum conditions within a Cameca ims-6f revealed that these factors were most likely to account for the adsorption of H2,02, and various gas phase-based organics onto the respective sputtered surfaces during acquisition of the energy-dependent depth profiles (van der Heide, unpublished observation). Note As covered in Section 4.2.1.1, molecular adsorption occurs even under high and ultrahigh vacuum conditions, i.e. one monolayer can form in as short a time as 10 s at 10 Torr. It is only the rate that is affected (see Relations 4.3 and 4.4). 

The dependence of the depth profiles, related directly to ion mixing as deduced above, on the ion energy and angle of incidence in Ge-Si specimens of various structures has also been studied, but since the angular dependence is rather weak, the results given are concerned only with the energy dependence of the mixing (20, 211. 

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