Memory device

A memory device, comprising:

• a memory cell including a first conductive layer, a second conductive layer, a third conductive layer provided between the first conductive layer and the second conductive layer, a switching layer provided between the first conductive layer and the third conductive layer, and a variable resistance layer provided between the third conductive layer and the second conductive layer,
• wherein the switching layer contains:
• an oxide, a nitride, or an oxynitride of a first element being at least one element selected from a group consisting of aluminum (Al), silicon (Si), germanium (Ge), zirconium (Zr), yttrium (Y), tantalum (Ta), lanthanum (La), cerium (Ce), titanium (Ti), hafnium (Hf), and magnesium (Mg);
• a second element being different from the first element, and being at least one element selected from a group consisting of aluminum (Al), zinc (Zn), tin (Sn), gallium (Ga), and indium (In);
• and
• a third element being at least one element selected from a group consisting of tellurium (Te), sulfur(S), selenium (Se), and antimony (Sb),
• wherein the switching layer includes a first region and a second region, and the second region is provided either between the first region and the first conductive layer or between the first region and the third conductive layer, and
• assuming that a sum of an atomic concentration of the first element, an atomic concentration of the second element, an atomic concentration of the third element, an atomic concentration of oxygen (O), and an atomic concentration of nitrogen (N) is a summed concentration,
• a first concentration obtained by dividing a sum of an atomic concentration of the second element and an atomic concentration of the third element in the first region by the summed concentration is higher than a second concentration obtained by dividing a sum of an atomic concentration of the second element and an atomic concentration of the third element in the second region by the summed concentration.