The defect depth distribution which was caused by 500eV N ion-beam etching of a Ga0.65Al0.35As/GaAs multiple quantum-well structure was investigated by means of confocal photoluminescence measurements performed on a bevelled section of the sample. A bevelled section, with the extremely small angle which was necessary for high depth-resolution was itself fabricated by means of ion-beam etching. The present 500eV N ion-beam etching technique led to a very low defect density, as compared with other ion-beam or plasma-assisted etching processes. A model, which accounted for diffusion effects in describing the profile, yielded a value of 4 x 10-15cm2/s for the defect diffusion coefficient.

F.Frost, K.Otte, A.Schindler, F.Bigl, G.Lippold, V.Gottschalch: Applied Physics Letters, 1997, 71[10], 1362-4