Disclosed are embodiments of a hetero-junction bipolar transistor (HBT) structure and method of forming the structure that provides substantially lower collector-to-base parasitic capacitance and collector resistance, while also lowering or maintaining base-to-emitter capacitance, emitter resistance and base resistance in order to achieve frequency capabilities in the THz range. The HBT is a collector-up HBT in which a dielectric layer and optional sidewall spacers separate the raised extrinsic base and the collector so as to reduce collector-to-base capacitance. A lower portion of the collector is single crystalline semiconductor so as to reduce collector resistance. The raised extrinsic base and the intrinsic base are stacked single crystalline epitaxial layers, where link-up is automatic and self-aligned, so as to reduce base resistance. The emitter is a heavily doped region below the top surface of a single crystalline semiconductor substrate so as to reduce emitter resistance.