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Spectral probing of carrier traps in Si–Ge alloy nanocrystals
Author(s) -
Ha Ngo Ngoc,
Giang Nguyen Truong,
Khiem Tran Ngoc,
Dung Nguyen Duc,
Gregorkiewicz Tom
Publication year - 2016
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201600304
Subject(s) - materials science , picosecond , nanocrystal , alloy , luminescence , analytical chemistry (journal) , absorption edge , germanium , optoelectronics , nanotechnology , chemistry , silicon , band gap , optics , metallurgy , laser , physics , chromatography
Photogenerated carriers in Si–Ge alloy nanocrystals (NCs) prepared by co‐sputtering method were investigated by mean of transient induced absorption. The carrier relaxation features multiple components, with three decay life times of τ ≈ 600 fs, 12 ps, and 15 ns, established for Si 0.2 Ge 0.8 alloy NCs of a mean crystal size of 9 nm and standard deviation of 3 nm. Deep carrier traps, identified at the boundary between the NCs and the SiO 2 host with the ionization energy of about 1 eV, are characterized by a long‐range Coulombic potential. These are responsible for rapid depletion of free carrier population within a few picoseconds after the excitation, which explains the low emissivity of the investigated materials, and also sheds light on the generally low luminescence of Si/Ge and Ge NCs. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)