Wider latitude for sophisticated devices by incorporating carbon into crystalline Si or SiGe

Research on highly supersaturated, carbon-containing alloys on silicon substrates started only a few years ago. Meanwhile, knowledge has been accumulated on growth, strain manipulation, thermal stability, carbon effects on band structure and charge carrier transport. We review basic mechanical and electrical material properties of Si_1-yC_y and Si_1-x-yGe_xC_y layers grown pseudomorphically on Si(001). Adding carbon alleviates some of the constraints for strained Si_1-xGe_x, and opens new possibilities for device application of heteroepitaxial Si-based systems. The incorporation of carbon is beneficial for: (i) improving SiGe layer properties; (ii) creating layers with new properties; and (iii) controlling dopant diffusion in microelectronic devices. A large variety of applications in microelectronic devices appears likely. The first device application ready for production is the npn-SiGe:C heterojunction bipolar transistor (HBT) with excellent static and high frequency performance.