Graphene base transistor and method for making the same

A graphene base transistor, comprising, on a semiconductor substrate surface:

• at least one emitter pillar and at least one emitter-contact pillar, which extend from a pillar foundation, through which they are electrically connected, in a vertical direction pointing perpendicularly away from the substrate surface;
• a dielectric filling layer laterally embedding the emitter pillar and the emitter-contact pillar, and separating them from each other in regions above the pillar foundation,
• an electrically conductive base-contact structure, which is either arranged on or embedded in the dielectric filling layer and which includes
• a) a base-contact face, which is arranged at a lateral distance from the emitter pillar, and,
• b) at least one base-contact arm, which extends from the base-contact face in a direction parallel to the substrate surface and passes between the top surfaces of the emitter pillar and of the emitter contact-pillar without directly contacting them;
• wherein the dielectric filling layer has an upper surface that is flush with a top surface of the emitter pillar and with the at least one base-contact arm
• a base layer of graphene forming a contiguous layer that extends between and covers an immediately adjacent top surface of the emitter pillar and at least a part of an immediately adjacent top surface of the at least one base-contact arm,
• a collector stack that comprises at least a collector-barrier layer, which is arranged immediately on the graphene layer, and an electrically conductive collector layer, which is arranged on the collector-barrier layer,
• wherein the collector stack and the base layer have the same lateral extension in a direction that is parallel to the substrate surface and perpendicular to those edges of the top surface of the emitter pillar and the base-contact arm that face each other.