No abstract

Density Functional Theory simulations have been used to identify the structural factors that define the material properties of OTS. They show that the nature of the mobility-gap states in amorphous Ge-rich Ge50Se50 is related to Ge-Ge bonds, whereas in Se-rich Ge30Se70 -Ge valence-alternating-pairs and Se lone-pairs are dominating. To obtain a faithful description of the electronic structure, delocalization of states, it is required to combine hybrid exchangecorrelation functionals with large unit-cell models. The extent of the localization of the electronic states depends on the applied external electric field. Hence, OTS materials undergo structural changes during the electrical cycling of the device, with a decrease in the population of less exothermic Ge-Ge bonds in favor of more exothermic Ge-Se. This reduces the amount of charge traps, which translates into coordination changes, increase in mobility-gap and subsequently changes the selector device electrical parameters. The threshold voltage drift process can be explained by the natural evolution of the non-preferred Ge-Ge bonds (or

A plasma-enhanced ALD process has been developed to deposit nickel phosphate. The process combines a trimethylphosphate (TMP) plasma with an oxygen plasma and nickelocene at a substrate temperature of 300°C....

Raman spectroscopy and electrical measurements are performed on sputtered GexSe1−x thin films to identify and link bond presence to electrical behaviour.