Low energy electron excited nanoscale luminescence spectroscopy of erbium doped AlN

We have investigated the optical activity of Er3+ ions in AlN via depth-res olved, (5 nm to 250 nm), low energy electron-excited nanoscale (LEEN) lumin escence spectroscopy and compared it with the luminescence of an Er-free Al N film. For the Er-free film, there was no emission in the IR from the AlN at any depth, and at higher energies we measured only a broad, weak feature between 1.7-3.25 eV along with an O defect related feature at 3.8 eV, whic h is significantly enhanced toward the surface. We found strong emission in the AlN:Er films from the first excited --> ground state transition of Er3 + 0.80 eV along with many other excited state transitions, although the fea tures are broad compared to those of GaN:Er. The AlN:Er luminescence satura tes near a concentration of 10(21) cm(-3), at which point we also observe e nhanced O defect related luminescence uniformly distributed throughout the film. This finding suggests a role for O in activating the Er at low Er con centrations, while inhibiting the Er activity at high O concentrations.