Depth profiles represent the composition of a layer or sample surface as a function of depth. For this analysis the sample surface has to be removed by suitable processes. This can be done either continuously (dynamic SIMS, GDOS) or iteratively (TOF-SIMS, XPS, AES).
In the iterative method a well defined, very thin layer of the surface is removed. This is usually done by sputtering with ions or cluster ions. Thereafter the newly formed surface is analyzed by the chooses analytical technique. After the analysis the next sputter step may follow. These iterative steps are repeated until the required depth is reached.