A transistor structure includes a base and a body over the base. The body comprises a semiconductor material and has a first end portion and a second end portion. A gate structure is wrapped around the body between the first end portion and the second end portion, where the gate structure includes a gate electrode and a dielectric between the gate electrode and the body. A source is in contact with the first end portion and a drain is in contact with the second end portion. A first spacer material is on opposite sides of the gate electrode and above the first end portion. A second spacer material is adjacent the gate structure and under the first end portion of the nanowire body. The second spacer material is below and in contact with a bottom surface of the source and the drain.