RECIPROCAL SPACE MAPS OF PBTE SNTE SUPERLATTICES/

PbTe/SnTe superlattices were grown on (111) BaF2 substrates by molecul ar beam epitaxy using PbTe as buffer layers. The individual layer thic kness and number of repetitions were chosen in order to change the str ain profile in the superlattices from completely pseudomorphic to part ially relaxed. The superlattices structural properties were investigat ed by making reciprocal space maps around the asymmetric (224) Bragg d iffraction points and omega/2 Theta scans for the (222) diffraction wi th a high resolution diffractometer in the triple axis configuration. With the strain information obtained from the maps, the (222) omega/2 Theta scan was simulated by dynamical diffraction theory. The simulate d spectra of the pseudomorphic superlattices, in which the in-plane la ttice constant is assumed to be the same as the PbTe buffer throughout the superlattice, fitted in a remarkably good agreement with the meas ured data, indicating that almost structurally perfect samples were ob tained. For the thicker superlattices, the (224) reciprocal space maps revealed a complex strain profile. Our results show the importance of detailed structural characterization on the interpretation of the ele ctrical properties. (C) 1998 American Institute of Physics. [S0021-897 9(98)03219-8]