Comparative investigation of InP/InGaAs abrupt, setback, and heterostructure-emitter heterojunction bipolar transistors

In this paper, the characteristics of InP/InGaAs abrupt, setback, and heterostructure-emitter heterojunction bipolar transistors (HBTs) are comparatively investigated by twodimensional simulation analysis. In the setback (heterostructure-emitter) HBT, a thin 50 $\mathring{\mathrm{A}}$ undoped In$_{0.53}$Ga$_{0.47}$As ($n$-In$_{0.53}$Ga$_{0.47}$As) layer is inserted between $n$-InP emitter and $p^+$-InGaAs base layers to lower the energy band at emitter side for decreasing the collector-emitter offset voltage. The simulated results exhibits that the abrupt HBT has the largest current gain, the largest collector-emitter offset voltage, and the smallest unity gain cutoff frequency. While, the setback and heterostructure-emitter HBTs exhibit the smallest current gain and offcet voltage, respectively. Consequentially, the demonstration and comparison of the three-type HBTs provide a promise for design in circuit applications.