SUPPRESSION OF PHONON REPLICA IN THE RADIATIVE RECOMBINATION OF AN MBE-GROWN TYPE-II GE SI QUANTUM-DOT/

Phonon-suppressed indirect-gap radiative recombination was observed fr om a type-II Ge/Si dot grown by gas source molecular beam epitaxy (MBE ). The phonon suppression occurs due to the formation of an electronic dot and the phononless k-diagonal Delta(1,c) - Gamma(25',v) interband recombination of three-dimensionally confined excitons is understood in the context of the elimination of momentum conservation. The dot co nfinement is established by large self-organized Stranski-Krastanow do ts and the interface trapping due to hole space charge. The dot charac teristics were confirmed by detailed measurements and the electronic d ot precursor was found near the growth mode transition. (C) 1998 Elsev ier Science SIA. All rights reserved.