A vertical tunneling, ultra-thin body transistor is formed on a substrate out of a vertical oxide pillar having active regions of opposing conductivity on opposite ends of the pillar. In one embodiment, the source region is a p+ region in the substrate under the pillar and the drain region is an n+ region at the top of the pillar. A gate structure is formed along the pillar sidewalls and over the body layers. The transistor operates by electron tunneling from the source valence band to the gate bias-induced n-type channels, along the ultra-thin silicon bodies, thus resulting in a drain current.