CDZNSE/ZNSE STRAINED-LAYER SUPERLATTICES DISORDERED BY GERMANIUM DIFFUSION

We have investigated the phenomenon of layer disordering in CdZnSe/ZnSe strained layer superlattices (SLSs) by Ge diffusion and have fabricated CdZnSe/ZnSe optical waveguides using the Ge-induced disordering. Both the as-grown sample and the sample annealed without a Ge layer showed several orders of well-resolved double crystal x-ray satellite peaks due to SLS periodic structure. However, the satellite peaks completely disappeared in the Ge-diffused sample, indicating that the SLS structure was disordered by the Ge diffusion and not caused by the annealing process. Photoluminescence (PL) measurements at 1.4K of both the as-grown and the annealed samples without Ge diffusion show intense, sharp excitonic emission around 483 nm in CdZnSe/ZnSe SLS. After Ge diffusion, the PL peaks shift to higher energy confirming the layer disordering of the SLS. The blue shift due to disordering was also observed in the PL at room temperature (RT). The optical guided mode in the SLS guiding layer confined by the disordered alloy was confirmed. Lateral optical confinement in the stripe geometry laser was also confirmed by observing the RT stimulated emission produced by optical pumping.