Low temperature electroformation of TaOx-based resistive switching devices

Transport characteristics of TiN/Ta/TaOx/TiN resistive-switching crossbar devices with amorphous TaOx functional layer have been investigated at cryogenic temperatures. Quasi-DC I-V characteristics at 10 K show a negative differential resistance region followed by a rapid transition to the non-volatile formed state. Accounting for Joule heating, the device temperature at the point of switching was estimated at 150 K. Measurements of transient resistance at low stage temperatures revealed an abrupt drop of resistance delayed by a characteristic incubation time after the leading edge of the voltage pulse. The incubation time was a strong function of applied voltage but did not depend on temperature between 10 K and 100 K. This implies a very low activation energy of the threshold switching process at low temperatures. Both of these observations argue against the involvement of oxygen vacancy motion at the onset of the forming process.