Impact of Ge Grading Profile on the Performance Characteristics of SiGe Heterojunction Bipolar Transistors

The DC characteristics of the different Ge grading profiles of the SiGe Heterojunction Bipolar Transistor (HBT) named as Linear increasing (LI), Symmetrically Triangular (ST), Hybrid Trapezoidal (HT), and Conventional Trapezoidal (CT) having 20% Ge contents is observed. After validation with experimental results, the four HBTs are simulated in the TCAD tool. The hybrid trapezoidal profile based SiGe HBT has the best DC characteristics like the highest current gain (294), the highest early voltage (-110 V), the lowest offset voltage (109 μV), and the lowest breakdown voltage (1.75 V) is observed.