Various examples are provided for ambipolar vertical field effect transistors (VFETs). In one example, among others, an ambipolar VFET includes a gate layer; a source layer that is electrically percolating and perforated; a dielectric layer; a drain layer; and a semiconducting channel layer. The semiconducting channel layer is in contact with at least a portion of the source layer and at least a portion of the dielectric layer and the source layer and the semiconducting channel layer form a gate voltage tunable charge injection barrier. Another example includes an ambipolar vertical field effect transistor including a dielectric surface treatment layer. The semiconducting channel layer is in contact with at least a portion of the source layer and at least a portion of the dielectric surface treatment layer and where the source layer and the semiconducting channel layer form a gate voltage tunable charge injection barrier.
