Electronic structure of amorphous insulators and semiconductors by X-ray photoelectron and soft X-ray spectroscopies

X-Ray Photoelectron Spectroscopy (XPS) and Soft X-Ray Spectroscopy (SXS) are attractive experimental methods which give complementary information on the electronic structure of amorphous insulators and semiconductors, By XPS, both core levels and valence band (VB) distributions are obtained, By soft X-Ray emission (XES) and absorption spectroscopies (XAS), local and symetry selected VB and CB states are determined. Consequently the XPS and SXS methods give quite complementary information concerning the electronic structure of materials. In this paper, the XPS and SXS methods are described and their possibilities are discussed. Results concerning the electronic structure of insulators and semiconductors specially in the case of amorphous silicon-based systems are discussed.