2015/10/29 by E. Vitiello, Elisa Vitiello, M. Virgilio +15 · 13 citations
Engineering · Materials Science · Physics and Astronomy · #Atomic physics #Circular polarization #Condensed matter physics #Doping #Electron paramagnetic resonance #Excitation #Excited state #Heterojunction #Materials science #Nanowire Synthesis and Applications #Nuclear magnetic resonance #Optics #Optoelectronics #Photoluminescence #Physics #Population #Radiative transfer #Semiconductor materials and devices #Silicon Nanostructures and Photoluminescence #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.92.201203
published in Physical Review B 92(20) (American Physical Society)
arxiv created 2015/10/29 · openalex publication_date 2015/11/19 · arxiv updated 2015/11/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The circular polarization of direct gap emission of Ge is studied in optically excited tensile-strained Ge-on-Si heterostructures as a function of doping and temperature. Owing to the spin-dependent optical selection rules, the radiative recombinations involving strain-split light (c\mathrm\ensuremathΓ-LH) and heavy hole (c\mathrm\ensuremathΓ-HH) bands are unambiguously resolved. The fundamental c\mathrm\ensuremathΓ-LH transition is found to have a low temperature circular polarization degree of about 85%, despite an off-resonance excitation of more than 300 meV. By photoluminescence (PL) measurements and tight-binding calculations we show that this exceptionally high value is due to the characteristic energy dependence of the optically induced electron spin population. Finally, our observation of a direct gap doublet clarifies that the light hole contribution, previously considered to be negligible, can dominate the room temperature PL even at low tensile strain values of \ensuremath≈0.2%.