We present a useful and simple technique to prepare controllable Er‐doped Si thin films using KrF excimer laser ablation. The sharp intense photoluminescence (PL) at 1.54 &mgr;m originating from the intra‐4fshell transition in Er3+ions was observed from 18 K up to room temperature. Characteristics of PL thermal quenching and time decay of prepared Er‐doped Si thin films are very similar to those of Er‐doped porous Si and/or Er‐doped amorphous Si. Furthermore, observation of Er3+emission from as‐prepared thin films without thermal annealing suggests that the Er doping in the form of Er atomic radical species produced by laser ablation is essential in activation of Er3+ions. Moreover, incorporating a prescribed amount of Er in the bulk target enables us to control the Er doping level in thin films prepared by laser ablation. ©1996 American Institute of Physics.