PHOTOSTRUCTURAL CHANGES IN AMORPHOUS AS50SE50 FILMS - AN EXAFS STUDY

An extended X-ray absorption fine-structure (EXAFS) study of amorphous As50Se50 films and the bulk glass has been performed. The data fitting of EXAFS spectra of annealed and illuminated films have shown that no appreciable changes occur within the first coordination sphere. Reversible changes have been observed when fitting the data at larger interatomic distances, which may imply an increase in the bond angle (and its fluctuations) subtended at the selenium atom (about 10°). A comparison of the absorption edges and Fourier-transformed spectra of bulk glass, as-evaporated film and annealed film provides evidence that, on annealing, the structure of the film does not approach that of the bulk glass. © 1990 Taylor & Francis Ltd.