Structural analysis of amorphous Ge0.5Te0.5 by neutron diffraction

Neutron diffraction measurements have been made on a sputtered sample of amorphous Ge_0.5Te_0.5. Analysis of the radial distribution function derived from Fourier inversion of the measured structure factor gives a nearest neighbor coordination number n = 2.49. This result, compared with coordination models proposed for this composition, favors the chemically ordered 3t2-3 model (where each Ge and Te atom is threefold coordinated by the other one) analogous to a-As with n = 2.78 over the 4-2 models with n > 3.20. More detailed analysis including second neighbor atoms confirms the ordered threefold a-As model.