Characterization of Compositional Gradients in Amorphous Semiconductor thin Films By Real Time Spectroscopic Ellipsometry

Abstract

ABSTRACTA new approach has been developed for the analysis of real time spectroscopie ellipsometry (RTSE) data that has important applications in characterizing compositionally-graded layers in amorphous semiconductor devices. The new RTSE data analysis approach determines (i) the instantaneous deposition rate, (ii) the surface roughness layer thickness, and (iii) the dielectric function of the near-surface layer (top 20 Å) of the growing film, all without any knowledge of the deposition history. We tested this new approach by characterizing a-Si1-xCx:H (x ∼ 0.09) alloy films with continuously graded void volume fractions. The results reported here are unique in that they represent the first successful optical analysis of amorphous semiconductor structures having continuously varying properties with depth into the film.