The interdiffusion of lateral composition-modulated (GaP)2/(InP)2 short-period superlattices was studied. Lateral compositional modulation was obtained by using the strain-induced lateral layer ordering process. A blue-shift of the inter-band transition was observed, by means of photoluminescence spectroscopy, in cap-less and SiO2-encapsulated annealed (800C, 5.5h) short-period superlattices. The intensity and wavelength of Si3N4-encapsulated annealed short-period superlattices were only slightly perturbed. Transmission electron microscopy showed that capless-annealed (800C, 5.5h) short-period superlattices retained their lateral composition modulation. However, the (00½) satellite reflections disappeared. After long (48h) annealing, the inter-band transition corresponded to that of an In0.50Ga0.50P alloy. This suggested that the lateral composition modulation disappeared. The observed lateral interdiffusion coefficient exceeded the vertical one by a factor of about 30; thus suggesting that short-period superlattice interdiffusion was enhanced by native point defects.

J.I.Malin, A.C.Chen, J.E.Bonkowski, J.E.Baker, K.Y.Cheng, K.C.Hsieh: Journal of Applied Physics, 1996, 80[2], 1233-5