The threshold characteristics of chalcogenide-glass memory switches

A detailed study is reported of the threshold characteristics of memory switches made from a chalcogenide glass of composition Ge₁₅Te₈₁S₂Sb₂. Most of the devices were fabricated by microelectronic processing techniques compatible with integrated-circuit technology. The main experimental feature is the systematic variation of the factors which influence the thermal parameters of the devices, i.e. temperature, geometry (thickness and radius of the active region of the switch) and substrate material. Measurements are also reported of the temperature and field dependence of the isothermal conductivity of the chalcogenide glass. Analysis shows that the results can be described adequately by an electrothermal model which takes into account the full field dependence of the isothermal conductivity and of the thermal fringing in the substrate.