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Due to the high bandgap (Eg =1.9eV) and etching selectively of In0.5 Ga0.5P material, the InGaP/GaAs material system has been proposed to replace the AlGaAs/GaAs. Undoped or lighted doped InGaP, with a relatively high resistance, was considered well as an “insulator”. The wide bandgap characteristics enhance the breakdown voltage and, thus, the power handling capabilities of the device for high power applications. From the device point of view, the high breakdown voltage is an important requirement for high power operations. The wide-gap InGaP was also used to increase the collector breakdown voltage in an NpN double heterojunction bipolar transistors (DHBT's). For InGaP/GaAs DHBT's, the electron blocking effect associated with the presented ΔEC between B-C heterojunction could cause a degraded current gain. Therefore, it is necessary to suppress the electron blocking effect which mainly resulting from the ΔEC at BC heterojunction.