Numerical Approaches to Non-Destructive Depth Profiling by Variable Angle X-Ray Photoelectron Spectroscopy

Variable angle x-ray photoelectron spectroscopy (VAXPS), also known as angle-resolved x-ray photoelectron spectroscopy (ARXPS), is a method which can be used to depth profile the near surface region non-destructively. The intensity variation with angle of a given energy level in a sample contains the complete information about the concentration profile of the photoionized component in the depth probed. It has been shown that the intensity is the Laplace transform of the concentration profile. Theoretically it should be possible to uniquely determine the concentration profile as the inverse Laplace transform of the intensity data. After a brief background sketch, the numerical approaches which have been used to solve the inverse Laplace transform problem in VAXPS are discussed