A transistor structure includes a stack of nanoribbons coupling source and drain terminals. The nanoribbons may each include a pair of crystalline interface layers and a channel layer between the interface layers. The channel layers may be a molecular monolayer, including a metal and a chalcogen, with a thickness of less than 1 nm. The channel layers may be substantially monocrystalline, and the interface layers may be lattice matched to the channel layers. The channel layers may be epitaxially grown over the lattice-matched interface layers. The crystalline interface layers may be grown over sacrificial layers when forming the stack of nanoribbons.