Erbium-doped Al2O3 films have been deposited in a single step process by pulsed laser deposition using independent ablation of Al2O3 and Er targets. This procedure allows to control the Er3+ ions in-depth distribution. The characteristic Er3+ photoluminescence at 1.54 μm shows lifetime values which increase from 6.0 to 7.1 ms when the Er3+–Er3+ in-depth separation is increased from 3 to 9 nm. These results are discussed in terms of the ion–ion interaction and clustering for separations shorter than 6 nm. © 1999 American Institute of Physics.