Mapping and simulation of processing-induced mechanical strain in GaAs laser diodes

We investigated the build-up of mechanical strain during the fabrication process of GaAs-based laser diodes. Test samples reproducing the geometrical features of the ridge waveguide, covered with metal thin films representative of the P contact layer, were characterized by mapping the degree of polarization of the photoluminescence from the facet. Experimental maps of the strain distribution were produced and compared to finite element simulations. This allowed us to quantify the amount of strain introduced by the metal thin film and identify the most critical parameters that influence this strain. This investigation opens the way to a design strategy for laser diodes with improved performances.