SHORT-RANGE ORDER IN AMORPHOUS GE(SE1-XSX)2

X-ray diffraction in combination with the Raman scattering measurement in amorphous Ge(Se1-xSx)2 was conducted on a range of compositions. T he first peak in the distribution function, g(r), is well resolved in all compositions and gives roughly four as the Ge coordination number, assuming that the peak contains only Ge-Se and Ge-S contributions, bu t not Se-Se, Se-S or S-S contributions. This result indicates that the se glasses are all formed by mixed-anion AX4-nYn tetrahedral units (n = 0-4). The Raman symmetric stretching frequencies of five tetrahedral units observed in the spectra were determined on the basis of the VFF analysis to be 201 cm-1 for GeSe4, 225 cm-1 for GeSe3S1, 233 and 245 cm-1 for GeSe2S2, 271 cm-1 for GeSe1S3 and 345 cm-1 for GeS4 units.