Memory devices and electronic systems include an array of vertical memory cells positioned along respective vertical channels to define vertical memory strings. Each of the vertical channels includes a channel material exhibiting an electron mobility of at least about 30 cm2/(V·s) and a room temperature band gap of at least about 1.40 eV (e.g., zinc oxide, silicon carbide, indium phosphide, indium gallium zinc oxide, gallium arsenide, or molybdenum disulfide) and a bottom plug material exhibiting a room temperature band gap of less than about 1.10 eV (e.g., silicon germanium, germanium, or indium gallium arsenide). Methods of fabricating a memory device include forming such a bottom plug material within vertical channels and forming such a channel material electrically coupled to the bottom plug material.