Vacancy-modulated conductive oxide resistive RAM device including an interfacial oxygen source layer

A method of operating a resistive memory element comprising a semiconductor material portion, a titanium oxide portion and a metal layer disposed between the semiconductor material portion and the titanium oxide portion, the method comprising:

• applying a set voltage to the element to generate oxygen interstitials and oxygen vacancies in the titanium oxide portion and to diffuse the oxygen interstitials to the metal layer to form an oxygen reservoir;
• and
• applying a reset voltage to the element to diffuse oxygen from the oxygen reservoir into the titanium oxide portion to provide the oxygen interstitials which recombine with the oxygen vacancies in the titanium oxide portion,
• wherein:
• the semiconductor material portion comprises an amorphous silicon portion;
• the metal layer comprises a titanium layer;
• the interfacial metal oxide layer comprises an oxygen deficient non-stoichiometric titanium oxide layer having a higher metal to oxygen ratio than the titanium oxide portion;
• the oxygen deficient non-stoichiometric titanium oxide layer has a formula TiO2-∈ in which ∈ is a variable number that changes with distance from the titanium oxide portion in range from 0.7 to 1.5;
• and
• the titanium oxide portion comprises a crystalline anatase titanium oxide which has a formula TiO2-δ in which 0≦δ≦0.3.

A method of forming a resistive memory element, comprising forming a combination of a semiconductor material portion and a titanium oxide portion with at least one interfacial layer therebetween, wherein the at least one interfacial layer comprises an element selected from Ti, Zr, Hf, Ta, Nb, and V and intermetallic alloys thereof,

• wherein:
• the at least one interfacial layer comprises an interfacial metal oxide layer consisting essentially of oxygen and at least one elemental metal selected from Ti, Zr, Hf, Ta, Nb, and V;
• the interfacial metal oxide layer is formed with an oxygen concentration gradient such that a concentration of oxygen increases with distance from the semiconductor material portion;
• the interfacial metal oxide layer comprises a non-stoichiometric metal oxide with oxygen deficiency;
• the semiconductor material portion comprises an amorphous semiconductor material selected from silicon, germanium, a silicon-germanium alloy, a silicon-carbon alloy, a silicon-germanium-carbon alloy, and a III-V compound semiconductor material;
• the semiconductor material portion comprises an amorphous silicon portion;
• a titanium layer is located between the interfacial metal oxide and the semiconductor portion;
• the interfacial metal oxide layer comprises an oxygen deficient non-stoichiometric titanium oxide layer having a higher metal to oxygen ratio than the titanium oxide portion;
• the oxygen deficient non-stoichiometric titanium oxide layer has a formula TiO2-∈ in which ∈ is a variable number that changes with distance from the titanium oxide portion in range from 0.7 to 1.5;
• the titanium oxide portion comprises a crystalline anatase titanium oxide which has a formula TiO2-δ in which 0≦δ≦0.3;
• and
• the resistive memory element is a non-filamentary memory element which changes resistivity due to oxygen interstitial diffusion during set and reset operations.