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Far‐infrared spectroscopy of shallow acceptors in semi‐insulating GaAs: evidence for defect interactions with EL2
Author(s) -
Alt H. Ch.,
Gomeniuk Y.,
Kretzer U.
Publication year - 2003
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.200301533
Subject(s) - shallow donor , infrared , analytical chemistry (journal) , infrared spectroscopy , acceptor , doping , impurity , zinc , absorption (acoustics) , fourier transform infrared spectroscopy , chemistry , absorption spectroscopy , spectroscopy , fermi resonance , materials science , condensed matter physics , optics , optoelectronics , physics , organic chemistry , chromatography , quantum mechanics , composite material
Far‐infrared FTIR absorption measurements are carried out at 10 K in order to assess the uncompensated fraction of shallow acceptors in semi‐insulating GaAs after optical bleaching of EL2. In carbon‐doped material a linear correlation of the G line at 122.3 cm –1 with the C As concentration is found in the whole concentration range between 1 × 10 14 and 2 × 10 16 cm –3 . In samples co‐doped with zinc in the range around 1 × 10 16 cm –3 and 1 to 2 × 10 15 cm –3 carbon, both, Zn Ga ‐ and C As ‐related far‐infrared absorption lines are observed. Taking into consideration the Fermi level position after bleaching of EL2, it can be concluded that no other donors than EL2 are present above a total concentration of 1 × 10 15 cm –3 . In addition to the far‐infrared measurements, the intracentre transition of EL2 (A 1 → T 2 ) at 1.0389 eV is studied. The results are compatible only with an increase of the total EL2 concentration with the shallow acceptor concentration. Possible mechanisms for the interaction between shallow‐ and deep‐level defects are discussed.