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Shallow Acceptors (shallow + acceptor)

Distribution by Scientific Domains

Physics and Astronomy	80%

Selected Abstracts

Study on electrical properties of Al/Cu(In,Ga)Se2 Schottky junction and ZnO/CdS/Cu(In,Ga)Se2 heterojunction using admittance spectroscopy

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2006
T. Sakurai
Abstract The electrical properties of Al/Cu(In,Ga)Se2 (Al/CIGSe) Schottky junction and ZnO/CdS/CIGSe heterojunction were studied by admittance spectroscopy. Three distinct peaks (peaks ,, ,, and ,) were detected from all the CIGSe samples. The activation energies for the traps corresponding to peaks , and , were estimated to be approximately 10 meV and 300 meV, respectively. The peak , may be due to the shallow acceptor, and peaks , and , may be due to defects in the CIGSe layer. The characteristics of the peak , have close correlation with the surface potential of the CIGSe layer. Therefore, the peak , may be caused by traps such as grain boundary defects near the surface of the CIGSe layer. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

High-field optically detected EPR and ENDOR of semiconductor defects using W-band microwave Fabry,Pérot resonators,

MAGNETIC RESONANCE IN CHEMISTRY, Issue S1 2005
J.-M. Spaeth
Abstract The designs of W-band (,95 GHz) Fabry,Pérot microwave resonators for optically detected EPR and ENDOR using the magnetic circular dichroism of the optical absorption (MCDA) as well as for photo-luminescence-detected EPR are briefly described. We report on the first MCDA-detected high-field EPR/ENDOR investigation of the paramagnetic EL2+ defect in semi-insulating GaAs. The higher-order effects, which prevented the unambiguous analysis of previous MCDA-detected K-band EPR/ENDOR experiments could be suppressed in W-band. The analysis of the ENDOR spectra showed that an extremely precise alignment of the samples is necessary. The paramagnetic El2+ defect turned out to be an As antisite defect, which has four almost equivalent nearest 75As neighbours differing less than 1.5% in the superhyperfine interactions suggestive of an isolated As antisite, while the third 75As shell (fifth neighbour shell) is clearly of lower symmetry than expected for an isolated As antisite. We discuss as a possible solution to this paradoxical situation that EL2+ is an isolated antisite at room temperature, which at low temperature, where all magnetic resonance experiments are performed, associates itself with shallow acceptors such as ZnGa, more than two nearest neighbour distances away. According to recent theoretical calculations, such ,loose' complexes with binding energies between 0.01 eV and 0.05 eV and disturb the equivalence of the nearest neighbour superhyperfine (shf) interactions less than 1.5%. Also, W-band EPR was measured using the photo-luminescence for detection to investigate P dopants in 6H-SiC. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Manifestation of the equilibrium hole distribution in photoluminescence of n-InN

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2005
A. A. Klochikhin
Abstract Photoluminescence (PL) of n-InN grown by molecular beam epitaxy with Hall concentrations from 3.6 to 7.3 × 1017 cm,3 demonstrates dependences on carrier concentration, temperature, and excitation density which give evidences of a fast energy relaxation rate of photoholes and their equilibrium distribution over localized states. The structure of the PL spectra observed at 4.2 and 77 K in the energy interval from 0.50 to 0.67 eV indicates that a considerable part of holes is trapped by deep and shallow acceptors before the interband recombi- nation with degenerate electrons occurs. At room temperature, the band-to-band recombination of free holes and electrons dominates in PL. Experimental results on PL and absorption are described by model calculations under the assumptions of a band gap equal to 0.665,0.670 eV at zero temperature and zero carrier concentration and a non-parabolic conduction band with the effective mass at the G -point equal to 0.07 of the free electron mass. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Far-infrared spectroscopy of shallow acceptors in semi-insulating GaAs: evidence for defect interactions with EL2

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2003
H. Ch.
Abstract 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 CAs concentration is found in the whole concentration range between 1 × 1014 and 2 × 1016 cm,3. In samples co-doped with zinc in the range around 1 × 1016 cm,3 and 1 to 2 × 1015 cm,3 carbon, both, ZnGa - and CAs -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 × 1015 cm,3. In addition to the far-infrared measurements, the intracentre transition of EL2 (A1 , T2) 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. [source]