Heitler-London model for acceptor-acceptor interactions in doped semiconductors

Abstract

The interactions between acceptors in semiconductors are often treated in qualitatively the same manner as those between donors. Acceptor wave functions are taken to be approximately hydrogenic and the standard hydrogen molecule Heitler-London model is used to describe acceptor-acceptor interactions. But due to valence band degeneracy and spin-orbit coupling, acceptor states can be far more complex than those of hydrogen atoms, which brings into question the validity of this approximation. To address this issue, we develop an acceptor-acceptor Heitler-London model using single-acceptor wave functions of the form proposed by Baldereschi and Lipari, which more accurately capture the physics of the acceptor states. We calculate the resulting acceptor-pair energy levels and find, in contrast to the two-level singlet-triplet splitting of the hydrogen molecule, a rich ten-level energy spectrum. Our results, computed as a function of inter-acceptor distance and spin-orbit coupling strength, suggest that acceptor-acceptor interactions can be qualitatively different from donor-donor interactions, and should therefore be relevant to the control of two-qubit interactions in acceptor-based qubit implementations, as well as the magnetic properties of a variety of p-doped semiconductor systems. Further insight is drawn by fitting numerical results to closed-form energy-level expressions obtained via an acceptor-acceptor Hubbard model.

arXiv comment19 pages, 10 figures, text revised, figure quality improved, additional references added

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Cited by in corpus (4)

• A linear combination of atomic orbitals (LCAO) model for deterministically placed acceptor arrays in silicon
• Quadrupolar interactions between acceptor pairs in p-doped semiconductors
• Multi-hole models for deterministically placed acceptor arrays in silicon
• Effect of compensation on magnetic ordering in (Ga,Mn)As