XPS analysis of a N-doped GaAs thin film using Ag Lα excitation

Nitrogen-doped GaAs (GaAs1-xNx) is finding application in high efficiency solar cells and vertical cavity surface emitting lasers (VCSELs). Nitrogen doping has been shown to cause perturbation of the host band structure. Determination of chemical state and nitrogen concentration is pivotal in defining the material’s electronic structure. X-ray photoelectron spectroscopy (XPS) is a commonly used technique for surface characterisation of this dilute N doped material.
In this application note we contrast the use of Al Kα and Ag Lα as excitation sources for XPS analysis of GaAs1-xNx. The advantage of using the higher photon energy excitation source to ‘remove’ overlapping Auger transitions with the N 1s core-level photoemission peak is demonstrated. Also introduced are advantages relating to the increased sampling depth provided by using the Ag Lα excitation for characterisation of a thin-film material.