Characteristics and optimizations of silicon BiCMOS transistors and integrated circuits

The performance of modern low-power high-speed heterojunction bipolar transistor (HBT) has been dramatically improved over the past decades with aggressive scaling of device feature size and optimizations of device layer structures. This thesis comprehensively summarizes the characterizations and optimizations of SiGe RF power HBTs and SiGe BiCMOS (bipolar-complementary metal-oxide-semiconductor) transistors and integrated circuits. The HBT characterizations include RF linearity characteristics of both common-emitter (CE) and common-base (CB) configurations. The performance of SiGe power HBTs and SiGe HBT-based power amplifiers are further investigated at extreme environment, such as radiation and extreme temperatures. Based on the characterizations, optimizations for the performance improvement of SiGe RF power HBTs are conducted, including power performance enhancement by using layout optimization and power handling capability improvement by using a novel bias scheme. Theoretical analyses, extensive simulations and experiments are conducted for these topics.;Besides the SiGe HBTs, another important active device family in the SiGe BiCMOS technology is complementary metal-oxide-semiconductor (CMOS) field-effect transistors (FETs). The metal interconnect of future high-density CMOS chips will eventually be replaced with high-speed optical interconnects. For these interconnects, monolithically integrating lasers on Si is essential. To ease the integration of III-V lasers on a Si CMOS chip, Si MOSFET devices have been attempted to fabricate on a 4° off-axis silicon substrate. To investigate the influences of the off-axis orientation on the performance of MOSFETs, the electron mobility of the MOSFET devices fabricated on different substrates is studied in detail and the underlying mechanisms are revealed by experimental results and theoretical analyses.;In parallel with the downscaling of the rigid substrate-based Si devices, flexible electronics based on soft substrates and flexible semiconductors have attracted great attention in recent years. In this dissertation study, an alternative method is developed to make low-cost flexible thin-film transistors on low-temperature plastics by applying a transfer technique to polycrystalline Si. By further applying the transfer technique to released single-crystalline Si nanomembrane (as waveguide for optical interconnects), low-loss on-chip single-crystalline Si waveguide is integrated with III-V optoelectronics.