Role of quantum confinement in luminescence efficiency of group IV nanostructures

International audienceExperimental results obtained previously for the photoluminescence efficiency (PLeff) of Ge quantum dots (QDs) are theoretically studied. A log-log plot of PLeff versus QD diameter (D) resulted in an identical slope for each Ge QD sample only when E-G similar to (D-2 + D)(-1). We identified that above D approximate to 6.2 nm: E-G similar to D-1 due to a changing effective mass (EM), while below D approximate to 4.6 nm: E-G similar to D-2 due to electron/hole confinement. We propose that as the QD size is initially reduced, the EM is reduced, which increases the Bohr radius and interface scattering until eventually pure quantum confinement effects dominate at small D. (C) 2014 AIP Publishing LLC