Metal-oxide-based conductive-bridging random access memory (CBRAM) having the solid electrolyte doped with a second metal

1. A resistive random access memory device comprising:

a first electrode made of inert material;

a second electrode made of soluble material;

a solid electrolyte, the first and second electrodes being respectively in contact with one of the faces of the electrolyte on either side of the electrolyte, the second electrode being configured to supply mobile ions circulating in the solid electrolyte to the first electrode to form a conductive filament between the first and second electrodes when a voltage is applied between the first and second electrodes;

wherein the solid electrolyte comprises a region of a first-metal oxide doped by a second metal, the second metal distinct from the first-metal and forming a second-metal oxide, said second metal selected such that the first-metal oxide doped by the second metal has a band gap energy less than or equal to a band gap energy of an undoped first-metal oxide material.

2. The device according to claim 1 , wherein the second metal is selected such that a band gap energy of the second-metal oxide is less than or equal to the band gap energy of the first-metal oxide.

3. The device according to claim 2 , wherein the first-metal oxide is gadolinium oxide Gd 2 O 3 and wherein the second metal is selected from the following metals:

hafnium Hf;

zirconium Zr;

titanium Ti.

4. The device according to claim 1 , wherein the band gap energy of the second-metal oxide is greater than the band gap energy of the first-metal oxide and wherein an atomic concentration of the second metal dopant within the region of the solid electrolyte is such that the first-metal oxide doped by the second metal has a band gap energy less than or equal to the band gap energy of the first-metal oxide not doped by the second metal.

5. The device according to claim 4 , wherein the first-metal oxide is gadolinium oxide Gd 2 O 3 and wherein the second metal is aluminum Al.

6. The device according to claim 1 , wherein the first-metal oxide is aluminum oxide Al 2 O 3 , zirconium dioxide ZrO 2 , titanium dioxide TiO 2 or tantalum oxide Ta 2 O 5 .

7. The device according to claim 1 , wherein the first-metal oxide doped by the second metal has a ratio R less than 1, the ratio R being expressed by: R=(M 1 +M 2 )/O, with M 1 the atomic concentration of first metal, M 2 the atomic concentration of second metal and O the atomic concentration of oxygen.

8. The device according to claim 1 , wherein an atomic percentage of the second metal within the region of the solid electrolyte is substantially comprised between 5% and 30%.

9. The device according to claim 8 , wherein the atomic percentage is comprised between 10% and 20%.

10. The device according to claim 1 , wherein the solid electrolyte further comprises:

a first sub-layer in contact with the first electrode made of inert material, and

a second sub-layer in contact with the second electrode made of soluble material;

and wherein the region of the first-metal oxide doped by the second metal is a central sub-layer located between the first sub-layer and the second sub-layer.

11. The device according to claim 1 , wherein the solid electrolyte is entirely formed by the region made of first-metal oxide doped by the second metal.