Steady-state level-anticrossing spectra for bound-exciton triplets associated with complex defects in semiconductors

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Abstract
A detailed analysis of magnetically induced level-anticrossing (LAC) effects for bound-exciton (BE) triplets associated with isoelectronic complex defects in semiconductors is presented, using rate equations and a spin Hamiltonian approach. It is shown that the observation of the LAC effects is due to nonvanishing microscopic interactions coupling the approaching states. In addition there exists an inequivalency between these states, due to a steady-state excitation mechanism. The hyperfine interactions are proved to be the main static interaction responsible for the LAC effects. Characteristic distinctions between different BE systems (from thermalized to unthermalized) are shown to exist in the vicinity of the LAC field region as well as for high magnetic fields. A good agreement between the treatment developed in the present work and experimental LAC spectra for several complex defects in GaP has been obtained. Useful information about the bound excitons and their associated defects can be extracted by simple steady-state level-anticrossing spectroscopy, i.e., in complete absence of external perturbing radiofrequency or microwave fields.