Abstract: A novel InGaAs/InP DHBT with a δ-doping sheet in the emitter and a N⁺ doping composite collector was designed. To analyze the characteristics of InGaAs/IhP DHBT, an analytical model is developed. Based on this model, the I-V characteristic, currents, and current gain are calculated. It is found that the I-V characteristics is improved with increasing the thickness of N⁺ layer and the doping concentration of N⁺ layer. When the δ doping concentration is greater than 2 × 10¹²cm^-3, current gain reaches a saturation value.