Confocal photoluminescence (PL) spectroscopy on an Al0.35Ga0.65As/GaAs multiple quantum well (MQW) structure has been utilized to study the damage depth profile induced by the ion beam etching (IBE) with argon and nitrogen. A high depth resolution of almost 2 nm has been achieved with this method using a MQW structure with monolayer thickness, a beveled sectioning technique with small inclination angles in the range of 1 X 10(-3) deg. resulting in a high stretching of the material depth along the beveled surface and spatially resolved confocal Fl, measurement. It is shown that the nitrogen IBE process causes significantly less loss on QW PL yield, and thus a lower defect concentration profile compared to the argon etching process. A model including diffusion effects was used to interpret the experimental results and yields a value for the defect diffusion coefficient of similar to 4 x 10(-15) cm(2)/s and similar to 12.3 x 10(-15) cm(2)/s for nitrogen- and argon-etched samples, respectively. For the determination of the near surface amorphization we carried out RBS/Channeling measurements.