Direct determination of the silicon donor ionization energy in homoepitaxial AlN from photoluminescence two-electron transitions

We report on the identification of a two-electron transition for the shallow donor silicon in homoepitaxial aluminum nitride (AlN). One c-oriented sample was analyzed by low temperature photoluminescence spectroscopy on multiple excitation spots. We find a unique correlation of one single emission band, 76.6 meV below the free excitonic emission, with the luminescence of excitons bound to neutral silicon proving the identity as a two-electron transition. The assignment is confirmed by temperature dependent photoluminescence investigations. We find a donor ionization energy of (63.5 +/- 1.5) meV for silicon in AlN. (C) 2013 AIP Publishing LLC.