Self aligned top extension formation for vertical transistors

A method of forming a semiconductor device that includes providing a vertically orientated channel region; and converting a portion of an exposed source/drain contact surface of the vertically orientated channel region into an amorphous crystalline structure. The amorphous crystalline structure is from the vertically orientated channel region. An in-situ doped extension region is epitaxially formed on an exposed surface of the vertically orientated channel region. A source/drain region is epitaxially formed on the in-situ doped extension region.