Phase-change memory cell with vanadium oxide based switching layer

A device, comprising, in sequence in the following order:

• 1) a first electrode layer;
• 2) a switching layer comprising vanadium oxide (VOx) material;
• 3) a phase-change material layer;
• and
• 4) a second electrode layer;
• wherein:
• the switching layer is adapted to control the phase-change material layer to switch between a crystalline state and an amorphous state when a voltage is applied to the first electrode layer and the second electrode layer,
• wherein the device is configured to
• 1) apply an electric pulse greater than a threshold voltage Vth of the switching layer between the first electrode layer and the second electrode layer, so that a temperature of the switching layer rises to be higher than its phase transition temperature, and the VOx material switches from a monoclinic crystal system in an insulating state to a tetragonal crystal system in a metallic state:
• 2) apply an electric pulse less than a holding voltage VoId of the switching layer between the first electrode layer and the second electrode layer, so that the temperature of the switching layer decreases to be lower than its phase transition temperature, and the VOx material returns to the monoclinic crystal system in the insulating state;
• 3) apply a resetting pulse having a voltage greater than a write operation threshold voltage VReset and a falling edge of 10 ns between the first electrode layer and the second electrode layer, so that the temperature of the phase-change material layer rises beyond melting temperature, the long-range order of the crystalline state is destroyed, and the phase-change material rapidly cools down below the crystallization temperature under the falling edge;
• there is no time for the phase-change material to crystallize;
• the phase-change material is in the amorphous state, and the phase-change material layer is in a low resistance state, to achieve a write operation;
• and
• 4) apply a setting pulse having a voltage between the phase transition voltage Vset of the phase-change material layer and the write operation threshold voltage VReset and a pulse width of 200 ns between the first electrode layer and the second electrode layer, so that the temperature of the phase-change material rises between the crystallization temperature and the melting temperature for 200 ns to ensure the crystallization of the phase-change material;
• the phase-change material changes from an amorphous state to a crystalline state, and the phase-change material layer is in a high resistance state, to achieve an erase operation.