Microelectronic devices, and related methods and memory devices

A method of forming a microelectronic device, comprising:

• forming a stack structure comprising levels of sacrificial material vertically alternating with levels of insulative material;
• forming a pillar structure to vertically extend through the stack structure, the pillar structure comprising semiconductor material;
• replacing portions of the sacrificial material of the levels of sacrificial material with an interfacial liner material having a work function within a range of from about 4.6 electronvolts (eV) to about 6.0 eV;
• and
• replacing additional portions of the sacrificial material of the levels of sacrificial material with a conductive material having a different work function than the interfacial liner material, the interfacial liner material horizontally interposed between the pillar structure and the conductive material.

A memory device, comprising:

• a stack structure including conductive structures vertically alternating with insulative structures, the conductive structures respectively comprising:
• an interfacial liner material comprising one or more of molybdenum oxide, molybdenum nitride, and molybdenum oxynitride;
• and
• conductive material neighboring the interfacial liner material and having a different material composition than the interfacial liner material;
• and
• strings of memory cells vertically extending through the stack structure, the interfacial liner of respective ones of the conductive structures of the stack structure horizontally interposed between channel material of the strings of memory cells and the conductive material of the respective ones of the conductive structures of the stack structure.