An investigation was made of the phenomenon of layer disordering in strained-layer superlattices due to Ge diffusion, and (Cd,Zn)Se/ZnSe optical waveguides were fabricated by using Ge-induced disordering. Both as-grown samples, and samples which had been annealed without a Ge layer, exhibited several orders of well-resolved double-crystal X-ray satellite peaks which were due to a strained-layer superlattice periodic structure. However, the satellite peaks completely disappeared from Ge-diffused samples, thus indicating that the strained-layer superlattice structure was disordered by Ge diffusion rather than by annealing. Photoluminescence measurements at 1.4K, of both as-grown and annealed samples without Ge diffusion, exhibited an intense sharp excitonic emission around 483nm in (Cd,Zn)Se/ZnSe strained-layer superlattices. After Ge diffusion, the photoluminescence peaks shifted to higher energies and confirmed layer disordering of the strained-layer superlattices. A blue shift which was due to disordering was also observed in the photoluminescence at room temperature.

T.Yokogawa, P.D.Floyd, J.L.Merz, H.Luo, J.K.Furdyna: Journal of Electronic Materials, 1994, 23[3], 283-7