A microelectronic device comprises a stack structure comprising a stack structure comprising alternating conductive structures and insulating structures arranged in tiers, each of the tiers individually comprising one of the conductive structures and one of the insulating structures, staircase structures within the stack structure and having steps comprising edges of the tiers, and a doped dielectric material adjacent the steps of the staircase structures and comprising silicon dioxide doped with one or more of boron, phosphorus, carbon, and fluorine, the doped dielectric material having a greater ratio of Si—O—Si bonds to water than borophosphosilicate glass. Related methods of forming a microelectronic device and related electronic systems are also disclosed.