Compositionally modified resistive electrode

An apparatus comprising:

• a chalcogenide memory element;
• and
• a heater element in thermal communication with the chalcogenide memory element, the heater element comprising:
• a first zone having a first resistivity and a first thermal coefficient of resistivity;
• and
• a second zone formed by exposing a portion of the first zone to an ambient and having a second resistivity and a second thermal coefficient of resistivity, wherein the first resistivity is lower than the second resistivity, and wherein the second thermal coefficient of resistivity has a less negative or positive variation to positive temperature change than the first thermal coefficient of resistivity.

An apparatus comprising:

• a plurality of memory elements, each memory element comprising a volume of memory material having two resistivity values, the volume of memory material being settable to one of the resistivity values in response to a selected electrical input signal;
• a conductor coupled to each memory element;
• and
• an electrode coupled to the volume of memory material and disposed between the volume of memory material and the conductor, the electrode comprising a first portion having a first resistivity value and a second portion having a different second resistivity value formed by exposing the electrode to an ambient.

A method comprising:

• introducing between two conductors formed on a substrate an electrode material;
• modifying a portion of the electrode material so that the electrode material comprises a first portion and a different second portion by exposing the electrode material to a gaseous ambient;
• and
• introducing a volume of memory material over the electrode material, the electrode material and the volume of memory material coupled to a conductor.