Further studies of memory switching in copper-calcium-phosphate glass devices

A series of copper-calcium-phosphate glasses was prepared and a simple method of construction of switching devices applicable to many oxdie glasses was introduced. All the glasses showed memory switching but a simple calcium-phosphate glass also showed threshold switching behaviour. There was a somehat random variation of threshold voltage as reported earlier by Drake. Switching on was easier at moderately elevated temperatures but switching off was harder. Electron-diffraction examination of the glass films prior to switching on with pressure contacts and subsequently, and also after having switched off by a high-current pulse, show that switching on is associated with a local amorphous-to-crystalline transition. The reverse process operates on switching off. It is suggested that the switching mechanism in these glasses is less likely to lead to degradation of characteristics with time than the process which operates in chalcogenido glass memory switches.