Device Parameter Optimization of Scaled Si-Ge Hetrojunction Bipolar Transistor

The immense demand for communication systems worldwide has created an enormous market for semiconductors devices (SiGe HBTs) in variegated applications. Nowadays SiGe HBTs are surpassing even the fastest III-V production devices in the GHz speed orbit. Scaling has been the prime source of supremacy behind the successful technology innovations. The design and optimization of un-scaled and scaled SiGe HBTs for the key performance parameter which affect the speed parameter in GHz frequency range has been explored extensively using appropriate scaling technique, which have recently emerged as a tough competitor for RF and mixed-signal applications. In this paper, the dynamic performance of un-scaled and scaled SiGe HBTs in terms of the cut off frequency, the maximum frequency of oscillation is investigated in a faultless approach with the help of Yparameter by ATLAS software from SILVACO. Both vertical and lateral scaling affect the device parameters. The impact of lateral scaling on cut off frequency is not as prominent as vertical scaling, but a certain level of lateral scaling needs to go along with vertical scaling Since maximum frequency of oscillation is absolutely associated to cut off frequency, the remuneration of vertical scaling on cut off frequency also apply to maximum frequency of oscillation, although the impact level is comparatively lower. However, maximum frequency of oscillation depends on RB and CCB, too, which are truly degraded by vertical scaling. As a result, the impact of vertical scaling on maximum frequency of oscillation is thorny, depending on structural details of the given device. On the other hand, lateral scaling, which has only some degree of influence on cut off frequency, plays a major role on maximum frequency of oscillation. The simulated results of un-scaled and scaled SiGe HBT are compared and contrasted.