SIGEC - BAND-GAPS, BAND OFFSETS, OPTICAL-PROPERTIES, AND POTENTIAL APPLICATIONS

Studying the structural and photoluminescence properties of pseudomorp hic Si1-yCy and Si1-x-yGexCy multiple quantum well (QW) structures on (001) Si substrates offer a quantitative characterization of the band gap and band offset shifts caused by C alloying for y < 3%. The main f eatures of Si1-yCy alloys, which are a reduced lattice constant and a strong lowering of the conduction band energy, promise that C may serv e as a counterpart to Ge in Si heteroepitaxy. The photoluminescent pro perties of Si1-yCy and SiGeC QWs are comparable to SiGe. Novel pseudom orphic Si1-yCy/SiGe coupled QW structures and Si1-yCy/Ge quantum dot s tructures result in a strong enhancement of the photoluminescent effic iency. The ternary SiGeC material system offers a higher degree of fre edom in strain and band edge,engineering of structures. We focus on ou r recent results on Si1-yCy and SiGeC QW layers embedded in Si concern ing the growth by solid-source molecular beam epitaxy, structural prop erties, thermal stability, optical properties, and band offsets. The p rospects of SiGeC alloys for realization of,optoelectronic structures are discussed. First characteristics from 0.75 mu m p-channel modulati on-doped field-effect transistor devices containing an active SiGeC la yer demonstrate good electrical properties. (C) 1998 American Vacuum S ociety.