Techniques relate to forming a vertical field effect transistor (FET). One or more fins are formed on a bottom source or drain of a substrate, and one or more fins extend in a vertical direction. Gate material is formed to be positioned on sides of the one or more fins. Gate encapsulation material is formed on sides of the gate material to form a trench, such that top portions of the one or more fins are exposed in the trench. A top source or drain is formed on top of the one or more fins such that the top source or drain is laterally confined by the trench in a lateral direction that is parallel to the one or more fins.