Skip to Main Content
Heterojunction bipolar transistor (HBT) fabrication on thin-film silicon-on-insulator (SOI) has been recently demonstrated. Due to the space volume constraint (thin film) for the device fabrication, the HBT structure is different from bulk HBT. In fact, compared to a bulk device, the buried layer has been suppressed and a lateral collector contact configuration is introduced. This device features a vertical expansion followed by a lateral expansion of the base-collector space charge region. This nonconventional charge behavior induces a kink in the base-collector junction capacitance characteristics, and as a consequence a modified Early effect. Furthermore, the low current transit time is modified compared to a bulk HBT. In this paper, all these effects are analyzed and a compact model for SOI-HBT is proposed. The model is validated on real SOI-HBTs with different collector doping levels.