The program demonstrated synthesis, optical and electrical characterizations, and device fabrication of GeSn and GeSiSn alloys integrated on Si platforms. These materials were produced via next generation deposition chemistries based on industrially viable hydride compounds. Emphasis was placed on the fabrication of direct-gap GeSn binaries grown on Ge buffered Si as well as light-emitting GeSiSn ternaries covering a broad band of tunable wavelengths from 1300 nm to 2500 nm for the first time. First generation GeSiSn LEDs and IR photodetectors were also demonstrated establishing the ternary as a thermally robust alternative to the binary for long wavelength applications. New breakthrough designs of direct-gap GeSn LEDs were introduced and shown to exhibit superior response relative to the state-of-the-art. The latter technology was further advanced via the creation of degenerate pn junctions representing the basic building block of quasi-direct diode lasers. The demonstration of electrically injected devices in this study was made possible by the ability to dope the materials p- and n-type at levels up to 10E20cm3 using practical in situ methods developed under the grant.