Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 36: Ge, GeSi, and Si
HL 36.11: Vortrag
Mittwoch, 24. März 2010, 12:15–12:30, H14
Isotope Effect on the Spin Resonance of Boron in Silicon — •Andre R. Stegner1, Hiroyuki Tezuka2, Till Andlauer1, Christoph Pellinger1, Kohei M. Itoh2, Martin Stutzmann1, and Martin S. Brandt1 — 1Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching — 2School of Fundamental Science and Technology, Keio University, Yokohama 223-8522, Japan
The fourfold degeneracy of the Boron acceptor ground state in silicon, which is easily lifted by any symmetry breaking perturbation, allows for a strong inhomogeneous broadening of the B-related electron paramagnetic resonance (EPR) lines, e.g. by randomly distributed, defect-induced local strain. In previous studies a number of fundamental questions concerning the line shape, the magnitude of the residual broadening, and the substructure of the B resonances have remained unsolved. We show that local fluctuations of the valence band edge due to the presence of different Si isotopes in the vicinity of the B acceptors can quantitatively account for all inhomogeneous broadening effects in high purity Si with a natural isotope composition. A comparison of our calculations with previous work investigating the B acceptor ground state in the absence of an external magnetic field, provides an independent verification of the energy offsets between the valence bands of 28Si, 29Si, and 30Si. Moreover, our calculations show that the isotopic perturbation also leads to a shift in the g-value of different B-related resonance lines, which could be verified in our experiments.