EurekAlert December 17, 2020
Silicon crystallized in the usual cubic (diamond) lattice structure has dominated the electronics industry for more than half a century. However, cubic silicon, germanium and SiGe alloys are all indirect-bandgap semiconductors that cannot emit light efficiently. An international team of researchers (Canada, the Netherlands, Germany, Austria) has demonstrated efficient light emission from direct-bandgap hexagonal Ge and SiGe alloys. They measured a sub-nanosecond, temperature-insensitive radiative recombination lifetime and observed an emission yield similar to that of direct-bandgap group-III–V semiconductors. They demonstrated that, by controlling the composition of the hexagonal SiGe alloy, the emission wavelength can be continuously tuned over a broad range, while preserving the direct bandgap. Their experimental findings are in excellent quantitative agreement with ab initio theory. Hexagonal SiGe embodies an ideal material system in which to combine electronic and optoelectronic functionalities on a single chip, opening the way towards integrated device concepts and information-processing technologies…read more. TECHNICAL ARTICLE
Overview of the hex-Si1 − xGex material system. Credit: Nature volume 580, pages205–209(2020)