APPLICATION OF SPECTRALLY RESOLVED SCANNING PHOTOLUMINESCENCE TO ASSESS RELAXATION PROCESSES OF INGAAS AND INALAS LAYERS STRAINED IN COMPRESSION AND TENSION

The objective of this contribution is to demonstrate the utility of ro om temperature scanning photoluminescence (SPL) techniques with high s patial resolution as an efficient, fast and non destructive approach t o study defects resulting from the relaxation of lattice mismatched ep itaxial layers strained in compression and tension. Experiments were c arried out on InGaAs and InAlAs layers with various compositions and t hicknesses grown by molecular beam epitaxy (MBE) or metal organic chem ical vapour deposition (MOCVD) on InP (001) substrates. We found that SPL images, which display the spatial distribution of spectrally integ rated photoluminescence intensity from investigated layers, reveal the presence of extended defects related to the relaxation process (e.g. misfit dislocation, ...). In addition, spectrally resolved SPL allows to assess lateral distribution of the bandgap and of the valence band splitting.