Temperature-dependent dc characteristics of an InGaAs/InGaAsP heterojunction bipolar transistor with an InGaAsP spacer and a composite-collector structure

The temperature-dependent dc characteristics of an interesting heterojunction bipolar transistor with an InGaAsP spacer and an InGaAs/InGaAsP composite-collector structure are studied and demonstrated. By employing the intermediate band-gap In_0.72Ga_0.28As_0.61P_0.39 material at the emitter-base and base-collector heterojunction, the electron blocking effect is effectively eliminated. The studied device gives the promising dc performances including the small offset and saturation voltages without degrading the breakdown behaviors. The typical incremental current gain of 114 and the maximum dc current gain of 118 are obtained. It is worthwhile to note that the desired current amplification over 11 decades of the magnitude of collector current I_C is obtained in the studied device. Moreover, the switching or hysteresis phenomenon usually observed in InP-based devices is not seen in the studied device.