Evidence of chlorine ion penetration in InP/InAsP quantum well structures during dry etching processes and effects of induced-defects on the electronic and structural behaviour

The samples are not really etched, but just exposed shortly to the plasma for the interaction to take place. Actually, we just etch at most a few tens of nanometers. Characterisation was carried out by spectrally-resolved cathodo-luminescence and photo-luminescence. We also measured secondary ion mass spectrometry profiles, which revealed the penetration of chlorine into the samples. High resolution transmission electron microscopy was used, to probe the crystal quality. By comparing doped and un-doped samples, we show that the chlorine observed after exposure consists at least partly in Cl− ions. The other important observation is some mechanical compressive stress, which is also a consequence of the local concentration of Cl impurities after exposure to the plasma.