Transistor And Methods Of Forming Transistors

A transistor comprises a top source/drain region, a bottom source/drain region, and a channel region vertically between the top and bottom source/drain regions. A gate is operatively laterally-adjacent the channel region. The top source/drain region, the bottom source/drain region, and the channel region respectively have crystal grains and grain boundaries between immediately-adjacent of the crystal grains. At least one of the bottom source/drain region and the channel region has an internal interface there-within between the crystal grains that are above the internal interface and the crystal grains that are below the internal interface. At least some of the crystal grains that are immediately-above the internal interface physically contact at least some of the crystal grains that are immediately-below the internal interface. All of the grain boundaries that are between immediately-adjacent of the physically-contacting crystal grains that are immediately-above and that are immediately-below the interface align relative one another. The internal interface comprises at least one of (a) and (b), where (a): conductivity-modifying dopant concentration immediately-above the internal interface is lower than immediately-below the internal interface and (b): a laterally-discontinuous insulative oxide. Other embodiments, including method, are disclosed.