Storage device and storage unit

Abstract

A storage device includes: a first electrode; a storage layer including an ion source layer; and a second electrode. The first electrode, the storage layer, and the second electrode are provided in this order. The ion source layer contains a movable element, and has a volume resistivity of about 150 mΩ·cm to about 12000 mΩ·cm both inclusive.

What is claimed is: 
     
         1 . A storage device, comprising:
 a first electrode;   a second electrode; and   a storage layer between the first electrode and the second electrode, the storage layer including an ion source layer,   wherein the ion source layer is positively or negatively ionized by application of an electric field, and   wherein the ion source layer has a volume resistivity of at least 150 mΩ·cm and less than or equal to 12000 mΩ·cm such that the storage layer has a low resistance state corresponding to first stored information, a high resistance state corresponding to second stored information, and at least one intermediate resistance state, between the low resistance state and the high resistance state, corresponding to third stored information.   
     
     
         2 . The storage device according to  claim 1 , wherein the ion source layer has the volume resistivity of about 450 mΩ·cm to about 3000 mΩ·cm both inclusive. 
     
     
         3 . The storage device according to  claim 1 , wherein the ion source layer contains oxygen. 
     
     
         4 . The storage device according to  claim 3 , wherein the ion source layer contains one or more elements selected from the group consisting of Group 4 elements, Group 5 elements, and Group 6 elements of the Periodic Table. 
     
     
         5 . The storage device according to  claim 1 , wherein the ion source layer is selected from the group consisting of titanium (Ti), zirconium (Zr), and hafnium (Hf) 
     
     
         6 . The storage device according to  claim 1 , wherein the ion source layer contains one or more elements selected from the group consisting of Group 16 elements of the Periodic Table. 
     
     
         7 . The storage device according to  claim 1 , wherein the ion source layer that is negatively ionized is selected from the group consisting of sulfur (S), selenium (Se), and tellurium (Te). 
     
     
         8 . The storage device according to  claim 1 , wherein the storage layer includes a resistance change layer provided closer to the first electrode than the second electrode. 
     
     
         9 . The storage device according to  claim 8 , wherein the resistance change layer is configured from a metal oxide film, a metal nitride film, or a metal oxynitride film 
     
     
         10 . The storage device according to  claim 8 , wherein the resistance change layer has a resistance value that varies in response to an application of a voltage to the first electrode and the second electrode. 
     
     
         11 . A storage unit with a plurality of storage devices and a pulse applier that selectively applies a voltage pulse or a current pulse to the storage devices, the storage devices each comprising:
 a first electrode;   a second electrode; and   a storage layer between the first electrode and the second electrode, the storage layer including an ion source layer   wherein the ion source layer is positively or negatively ionized by application of an electric field, and   wherein the ion source layer has a volume resistivity of at least 150 mΩ·cm and less than or equal to 12000 mΩ·cm such that the storage layer has a low resistance state corresponding to first stored information, a high resistance state corresponding to second stored information, and at least one intermediate resistance state, between the low resistance state and the high resistance state, corresponding to third stored information.   
     
     
         12 . The storage unit according to  claim 11 , wherein the ion source layer has the volume resistivity of about 450 mΩ·cm to about 3000 mΩ·cm both inclusive. 
     
     
         13 . The storage unit according to  claim 11 , wherein the ion source layer contains oxygen. 
     
     
         14 . The storage unit according to  claim 13 , wherein the ion source layer contains one or more elements selected from the group consisting of Group 4 elements, Group 5 elements, and Group 6 elements of the Periodic Table. 
     
     
         15 . The storage unit according to  claim 11 , wherein the ion source layer is selected from the group consisting of titanium (Ti), zirconium (Zr), and hafnium (Hf). 
     
     
         16 . The storage unit according to  claim 11 , wherein the ion source layer contains one or more elements selected from the group consisting of Group 16 elements of the Periodic Table. 
     
     
         17 . The storage unit according to  claim 11 , wherein the ion source layer that is negatively ionized is selected from the group consisting of sulfur (S), selenium (Se), and tellurium (Te). 
     
     
         18 . The storage unit according to  claim 11 , wherein the storage layer includes a resistance change layer provided closer to the first electrode than the second electrode. 
     
     
         19 . The storage unit according to  claim 18 , wherein the resistance change layer is configured from a metal oxide film, a metal nitride film, or a metal oxynitride film. 
     
     
         20 . The storage unit according to  claim 18 , wherein the resistance change layer has a resistance value that varies in response to an application of a voltage to the first electrode and the second electrode.