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 room temperature scanning photoluminescence (SPL) techniques with high spatial resolution as an efficient, fast and non destructive approach to study defects resulting from the relaxation of lattice mismatched epitaxial layers strained in compression and tension. Experiments were carried out on InGaAs and InAlAs layers with various compositions and thicknesses grown by molecular beam epitaxy (MBE) or metal organic chemical vapour deposition (MOCVD) on InP (001) substrates. We found that SPL images, which display the spatial distribution of spectrally integrated 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.