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Electron paramagnetic resonance of the shallow Si donor in indirect GaAs/AlxGa1-xAs heterostructures.

Elektronen-Spin-Resonanz des flachen Si-Donators in indirekten GaAs/AlxGa1-xAs Heterostrukturen
: Wilkening, W.; Kaufmann, U.

Davies, G.:
Shallow impurities in semiconductors. Proceedings of the Fourth International Conference on Shallow Impurities in Semiconductors
Zürich: Trans Tech Publications, 1991 (Materials Science Forum 65/66)
ISBN: 0-87849-619-X
pp.397-402 : Abb.,Lit.
International Conference on Shallow Impurities in Semiconductors <4, 1990, London>
Conference Paper
Fraunhofer IAF ()
AlGaAs; DX; EPR; ESR; heterostructure; Heterostruktur; strains; Verspannung

We report electrom paramagnetic resonance (EPR) results for the shallow effective mass ground state 1s(T2) of the Si donor associated with the X valleys in indirect (x bigger than 0,4) AlxGa1-xAs:Si layers grown on GaAs. EPR data taken in thermal equilibrium confirm that the heteroepitaxial strain splits the three X valleys such that the Xz valley lies above the Xx and Xy valleys. An independent valley model perfectly accounts for the symmetry properties of the donor resonance over the full indirect gap range of the alloy withhout inclusion of spin-valley interaction. This unexpected results is attributed to local, random in-plane strains which quench the first order spin-valley splitting. Photo EPR and low temperature annealing studies of the photo-enhanced shallow donor signal provide also information on the deep DX state of Si. In particular the data confirm the incase of the DX capture barrier height with increasing Al content within the indirect alloy range.