Abstract: A composite collector structure containing InGaAsP was designed,which can effectively eliminate the energy spike at the B-C junction and avoid the current blocking effect.The dependence of the characteristics of a DHBT on the parameters of the collector structure were analyzed theoretically,and an optimized result was delivered which can give a theoretical direction and reference for the design of this kind of composite collector.The data were analyzed based on the theory of this paper,and a satisfactory result was obtained.

Key words: InP/InGaAs, HBT, composite collector, barrier spike