Local atomic environment in amorphous Ge₁₅Te₈₅

Abstract

The structure of amorphous Ge15Te85 has been studied by neutron and x-ray diffraction. Experimental data have been modelled simultaneously with the reverse Monte Carlo simulation method. The contrast between structure factors together with the application of some plausible physical constraints allowed the separation of the three partial pair correlation functions and determination of Ge and Te local environment.

Local order in amorphousGe2Sb2Te5andGeJóvári1, Kaban2, Steiner3 et al. 2008Phys. Rev. B15320834View full textAdd to dashboardCite

“…Figure 6 shows the Te-Ge-Te BAD's of amorphous Ge 2 Sb 2 Te 5 and Ge 15 Te 85 . 21 In the case of the binary alloy, the peak is at about 107°, which is very close to the tetrahedral angle ͑109.47°͒. Due to the asymmetry of g GeTe ͑r͒, the Te-Ge-Te BAD of amorphous Ge 2 Sb 2 Te 5 is somewhat sensitive to the cutoff distance used for bond angle calculations.…”

Determination of partial pair distribution functions in amorphous Ge15Te85 by simultaneous RMC simulation of diffraction and EXAFS data

“…These two factors may lead to the 'mixing' of overlapping r-space peaks, i.e. individual peak positions may shift towards the centre of mass of the two peaks in the RMC simulated g(r)s. This effect can really be seen in [1] where the mean Ge-Te distance was longer while the mean Te-Te distance was shorter than the majority of literature values.…”

“…Recently we carried out X-ray diffraction (XRD) and neutron diffraction (ND) study on amorphous Ge 15 Te 85 and analyzed the experimental data with reverse Monte Carlo (RMC) simulation method [1]. In principle, the separation of the three partial pair correlation functions of a binary sample requires three independent diffraction datasets.…”

“…and the neutron scattering lengths (b Ge = 8.185 fm, b Te = 5.8 fm [5]) for Ge and Te XRD and ND data give complementary information on the structure of amorphous Ge 15 Te 85 . In our previous study [1], the homopolar bonding between Ge atoms was excluded by setting their minimum distance to as high as 3.5 Å . This way it was possible to separate g GeGe (r) from g GeTe (r) and g TeTe (r).…”

Structural studies on Te-rich Ge–Te melts

“…On the base of Raman scattering data we assumed in our previous paper [26] that there are no Ge-Ge bonds in amorphous Ge 15 Te 85 . It is reasonable to assume that this also holds for liquid Ge 15 Te 85 in the vicinity of the melting point.…”