Arsenic doped amorphous silicon layers have been deposited on silicon single crystals by rf cathodic sputtering of a silicon target in a reactive argon‐hydrogen mixture, and annealed with aQ‐switched ruby laser. Topographic analysis of the laser irradiated layers indicate that a crater is formed due to an evaporation of material which could be related to the presence of a high concentration of argon in these deposited films. Furthermore, Rutherford Backscattering experiments showed that a highly disordered surface layer is left after irradiation due probably to an inhibition of the recrystallization by the presence of hydrogen as revealed by nuclear reaction analysis. Nevertheless, it was found that below this surface layer arsenic has diffused into the monocrystalline substrate. Therefore, under convenient experimental conditions, (repetitive laser pulses),p‐njunctions of good quality could be formed.