A heterojunction bipolar transistor (HBT) and methods of fabrication provide a substrate, a base having a first lateral area, an emitter, a sub-collector having a second lateral area, and a collector above the sub-collector, wherein the second lateral area of the sub-collector is less than the first lateral area of the base, which enables the fabrication of HBTs with high linearity, as measured by an improved third order distortion (OIP3) parameter, while maintaining high gain; which enables the fabrication of HBTs with a selectively grown or overgrown collector/sub-collector; and which reduces a capacitance between the base and collector of the HBTs.