DENSITIES OF STATES OF SEMICONDUCTORS BY SOFT-X-RAY SPECTROSCOPY

Soft X-ray spectroscopy (SXS) allows to obtain electronic distributions which are of a given angular momentum character due to dipole selection rules and which concern the different constituants of a solid since a core level is involved in the X-ray process. Thus from complementary emission (SXES) and photoabsorption (SXAS) spectra involving respectively the valence and the conduction bands, information on the occupied and unoccupied densities of states can be reached separately. With these two experimental methods, investigation of elemental, III-V, IV-IV or IV-VI semiconductors has been performed. We report on several results concerning p or s densities of states of Si, P and Ge in pure elements and several alloys and compounds and we compare them to theoretical calculations when available. Attention is focused on the effects of disorder, alloying and hydrogen incorporation on the densities of states. © 1990.