In some embodiments, a transistor includes a stack having a bottom source/drain region, a first insulative material, a conductive gate, a second insulative material, and a top source/drain region. The stack has a vertical sidewall with a bottom portion along the bottom source/drain region, a middle portion along the conductive gate, and a top portion along the top source/drain region. Third insulative material is along the middle portion of the vertical sidewall. A channel region material is along the third insulative material. The channel region material is directly against the top and bottom portions of the vertical sidewall. The channel region material has a thickness within a range of from greater than about 3 Å to less than or equal to about 10 Å; and/or has a thickness of from 1 monolayer to 7 monolayers.