MPI für Festkörperforschung / FKF Publikationen 2003 |
|Ge hut cluster luminescence below bulk Ge band gap|
|Authors:||Denker, U.; Stoffel, M.; Schmidt, O. G.; Sigg, H.|
|Date of Publication (YYYY-MM-DD):||2003|
|Title of Journal:||Applied Physics Letters|
|Issue / Number:||3|
|Abstract / Description:||We report on the photoluminescence (PL) properties of Ge hut
cluster islands on Si(001) that were overgrown at temperatures
as low as 250 degreesC. We find that the island-related
photoluminescence systematically redshifts as the overgrowth
temperature is reduced from 500 to 360 degreesC, which is
attributed to a reduced Ge segregation. For even lower
overgrowth temperatures, the emission energy saturates at 0.63
eV or 1.96 mum, more than 110 meV smaller than the band gap of
unstrained bulk Ge. We report a PL peak centered at 2.01 mum at
low excitation power, in good agreement with the estimated
transition energy for a spatially indirect transition between
holes confined in the strained Ge island and electrons confined
in the surrounding Si matrix. PL is observed up to a
temperature of 185 K and an activation energy of 40 meV is
deduced from fitting the temperature-dependent peak intensity.
Annealing experiments reveal a systematic blueshift of the hut
cluster-related PL, thus verifying unambiguously, that the PL
signal originates from the hut clusters and not from defects.
(C) 2003 American Institute of Physics.
|External Publication Status:||published|
|Communicated by:||Michaela Asen-Palmer|
|Affiliations:||MPI für Festkörperforschung|
|External Affiliations:||; Max Planck Inst Festkorperforsch, Heisenbergstr 1, D-70569 Stuttgart, Germany
; Paul Scherrer Inst, CH-5232 Villigen, Switzerland
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