This paper reviews the different specifications required for a high yi
eld and low cost epitaxial process of heterojunction bipolar transisto
r (HBT) structures on GaAs and InP substrate. For these two semiconduc
tor systems, it is shown that arsenide/phosphide heterostructures and
carbon doping of the npn HBT base layer lead to both high device relia
bility and simple and reproducible HBT fabrication process. Other requ
irements concerning high growth rate, low and constant growth temperat
ure, high growth uniformity on several wafers as well as low surface d
efect density are also identified. It is shown that chemical beam epit
axy (CBE) and metal-organic vapor phase epitaxy (MOVPE) techniques fit
all these requirements while molecular beam epitaxy (MBE) must be imp
roved on specific points.