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Charge transition level of GeP b1 centers at interfaces of SiO 2 /Ge x Si 1− x /SiO 2 heterostructures investigated by positron annihilation spectroscopy
Author(s) -
Madia O.,
Segercrantz N.,
Afanas'ev V.,
Stesmans A.,
Souriau L.,
Slotte J.,
Tuomisto F.
Publication year - 2014
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201400040
Subject(s) - spectroscopy , dangling bond , materials science , germanium , electron paramagnetic resonance , fermi level , atomic physics , condensed matter physics , analytical chemistry (journal) , chemistry , electron , silicon , nuclear magnetic resonance , physics , optoelectronics , quantum mechanics , chromatography
In this work, we address the charge trapping properties of Ge dangling bond (DB) defects – GeP b1 centers as typified by electron spin resonance spectroscopy (ESR) – found at the interfaces between condensation‐grown Si 1− x Ge x (0.28 < x < 0.8) alloys and insulating SiO 2 . The ESR observation of singly‐occupied paramagnetic GeP b1 centers, carried out at 4.3 K, is complemented by temperature‐dependent positron annihilation spectroscopy (PAS) in the Doppler broadening mode, which enables observation of the neutral‐to‐negative defect transitions as the temperature increases from 50 to 300 K. Through correlation of this re‐charging behavior with the temperature‐induced shift of the Fermi energy, the energy of the Ge DB −/0 transition in the Si 0.27 Ge 0.73 alloy is inferred to be energetically distributed in a ∼0.1 eV interval above the top of the semiconductor valence band. This result refines previous estimates from capacitance–voltage measurements, thus providing independent affirmation that the energy levels of Ge DBs lie inside the band gap of the Si 1− x Ge x alloys.