Erbium-doped Si1-xGex/Si structures for light emitting diodes

LEDs have been fabricated from erbium-doped Si and Si1-xGex quantum wells, and exhibit radiation at 1.54 mu m when operated in forward bias. The strai ned Si1-xGex/Si quantum wells were doped with erbium, either by implantatio n or during MBE growth, for two germanium fractions, 13% and 25% respective ly, and their quality was monitored by transmission electron microscopy. PL measurements as a function of temperature exhibit a dependence of the high temperature signal quenching on the germanium fraction. The forward-bias E L and PL from the Er:Si1-xGex, exhibit different emission energies irrespec tive of whether the samples are ion implanted or doped during MBE growth. T he energy changes are attributed to confinement of injected holes in the el ectroluminescence measurement by the quantum wells, and subsequent excitati on of a different set of Er atoms which may be in the Si1-xGex host. Electr ic field effects have been eliminated by performing the EL and PL under ide ntical conditions. This is very encouraging for the potential use of SiGe w aveguides in future injection-type silicon-based LEDs.