Far-infrared absorption spectra of the ground-state–to–excited-state transitions of excitons bound to the double acceptors Be and Zn in Ge

Fourier-transform far-infrared absorption spectroscopy has been used to detect ground-state--to--odd-parity--excited-state transitions in bound excitons associated with the double acceptors Be and Zn in Ge. The energy of the principal transition of the Zn spectrum is in good agreement with a previous magnetoabsorption measurement, but more fine structure is observed in the present results. The new results for the Be bound exciton show even more detailed fine structure, and the excited states for both systems are shown to be in excellent agreement with a pseudodonor model. The far-infrared transition energies support a recent reinterpretation of the Ge:Zn photoluminescence spectrum.