Electron beam effects in Ge–Se thin films and resistance change memory devices

Abstract

Chalcogenide glasses are the advanced materials of choice for the emerging nanoionic memory devicesconductive bridge random access memory (CBRAM). To understand the nature of the effects occurring in these devices under influence of electron-beam radiation, the interaction of blanked chalcogenide films and nanostructured films containing chalcogenide glass and silver (Ag) source are studied. Raman spectroscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction are used for establishing the structural and compositional effects occurring under radiation. They have strong compositional dependence with the stoichiometric compositions being most stable showing less structural changes after radiation. These effects are associated with the availability of lone-pair electrons, their participation in the bonding configurations and the coupling of electron states in the bandgap. They are further enhanced in the bilayers by silver diffusion in the chalcogenide matrix, as a result of interaction with electrons. These effects are used to interpret the electrical performance of CBRAM devices after radiation. The devices are characterized by their resistance states, threshold voltage and endurance. Those based on selenium-rich and stoichiometric composition undergo continuous parameters changes with increase in the radiation dose while in the devices based on germanium-rich composition a counter play of the structural changes and expulsion of silver occur.

Proton Beam Effects on Ge–Se/Ag Thin Films

“…When Ag film is in contact with the chalcogenide film, the impact of electrons over Ag diffusion, distribution and migration within the chalcogenide glasses is well expressed, which also changes the performance of CBRAM devices because of the key role that Ag has in their operation.…”

“…There is one more detail that has to be considered in the plurality of effects occurring by interaction of charged particles with chalcogenide glasses and coupled to them Ag films − the compositional dependence of the chalcogenide glass. Studies show that the Ge–rich glasses of the Ge–Se system are highly sensitive when interacting with radiation of electrons or Ar + ions . This seems to be related to the fact that these glasses contain Ge–Ge bonds which are the weakest among all bonds present in these structures.…”

“…They can easily break, but recombination of the formed dangling bonds does not occur easily because of the structural rigidity of the glass. On the other hand, devices based on Ge–rich composition are more stable, and this makes devices based for example on Ge 40 Se 60 worth studying in terms of their application in CBRAM devices.…”

Preferred location for conducting filament formation in thin-film nano-ionic electrolyte: study of microstructure by atom-probe tomography

“…But the role of non-uniformity in the a-Ch on the formation of CFs remains unknown. A major experimental difficulty is that the imaging technique itself can induce structural modifications and damage [23].…”

Editorial

“…The electron density quickly decreases with radial direction, while the density is larger in the center of the Brillouin zone in the angular direction. 12 Chalcogenide glasses are the advanced materials of choice for the emerging nanoionic memory devices -conductive bridge random access memory (CBRAM). In order to understand the nature of the effects occurring in these devices, under the influence of electron-beam radiation, the interaction of blanked chalcogenide films and nanostructured films containing chalcogenide glass and silver (Ag) source were studied.…”