(Invited) Integration of InP Heterojunction Bipolar Transistors on Silicon Substrates for 6G Networks

The power amplifier (PA) in an RF front-end module operating above 100 GHz required for 6G wireless networks is the most power-hungry device circuit component. In that respect, InP-based heterojunction bipolar transistors (HBT) clearly outperform other PA technologies, but being processed on small size wafers, they lack a cost-effective fabrication for mass production. This paper presents a comprehensive comparison of various integration approaches for InP-based HBTs. A key aspect in achieving high yield device fabrication is the use of large-diameter silicon wafers. This study discusses the advantages and disadvantages of different InP-based HBT integration concepts on Si, emphasizing important factors for upscaling InP technologies. Furthermore, this work introduces nano-ridge engineering (NRE), a novel monolithic III-V integration approach currently being explored at imec, which holds the potential for cost-effective and complementary metal oxide semiconductor (CMOS)-compatible production.