Chemical states of GeTe thin-film during structural phase-change by annealing in ultra-high vacuum

Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films

“…that the phase change in GeTe has to be attributed mainly to local symmetry changes with no change in the charge density around Ge 24 . The latter interpretation has been supported by synchrotron-based XPS experiments 25 , while different groups have reported changes in the electronic structure of a-GeTe and c-GeTe 26 . The evident controversy in the interpretation of XPS results underlines the need for an experimental method more sensitive to the very small valence state changes occurring at the Ge site during the amorphous-to-crystalline GeTe phase transition.…”

Effect of Ag photo-doping on structural, optical and phase change properties of GeTe chalcogenide films

“…amount Ag in GeTe films with photodoping. For pure GeTe film, the diffraction pattern of devitrified films revealed NaCl-like fcc structure [5], with the peak of maximum intensity at 29.831 corresponding to (200) plane along with a week diffraction peak of GeTe 2 phase. The devitrified photo-diffused films showed diffraction peaks corresponding to GeTe phase only.…”

“…The nanosecond switching in GeTe alloy films in confined geometry together with high resistance change upon crystallization and the non-volatile retention of data is very promising for its device applications [4]. It has been reported by high resolution X-ray photoelectron spectroscopy that the structural environment of Ge atom changes during phase transition and not its chemical environment [5]. The sandwiched Ag-rich Ge-Te electrolyte films in the programmable metallization cell structure have shown the promising performance for their non-volatile random access memory applications [6][7][8].…”

Chemical states of Bi-doped GeTe (Bi: 6 at.%) thin film in structural phase transition investigated by synchrotron X-ray photoelectron spectroscopy

“…It is apparent that the binding energy and the peak shape of the Te 4d core-level showed little change after annealing. This might imply that the Te atom was firmly fixed at a certain site (such as the Na site in the NaCl structure) and underwent no change in its chemical state [16,17]. In the case of the Ge 3d 5/2 and Bi 4f 7/2 core-levels, their binding energies in the meta-stable crystalline phase were 29.9 and 157.9 eV, respectively.…”