  Semiconductor light emitters compatible with standard Si integration
technology (SIT) are of particular interest for overcoming limitations in the
operating speed of microelectronic devices 1-3. Light sources based on group-IV
elements would be SIT compatible but suffer from the poor optoelectronic
properties of bulk Si and Ge. Here, we demonstrate that epitaxially grown Ge
quantum dots (QDs) in a fully coherent Si matrix show extraordinary optical
properties if partially amorphised by Ge-ion bombardment (GIB). The GIB-QDs
exhibit a quasi-direct-band gap and show, in contrast to conventional SiGe
nanostructures, almost no thermal quenching of the photoluminescence (PL) up to
room-temperature (RT). Microdisk resonators with embedded GIB-QDs exhibit
threshold-behaviour and super-linear increase of the integrated PL-intensity
(IPL) with increasing excitation power Pexc which indicates light amplification
by stimulated emission in a fully SIT-compatible group-IV nano-system.
