HIGH-RESOLUTION X-RAY-DIFFRACTION CHARACTERIZATION OF PIEZOELECTRIC INGAAS GAAS MULTIQUANTUM WELLS AND SUPERLATTICES ON (111)B GAAS/

In this paper we show some examples of strained InGaAs/GaAs multilayer s on (111)B GaAs substrates studied by high-resolution X-ray diffracto metry. The samples consisted of a multiquantum well or superlattice em bedded in the intrinsic region of a p-i-n photodiode. We have analysed piezoelectric (111)B structures with 3, 7, 10, and 40 periods and dif ferent indium contents and compared the results with identical structu res simultaneously grown on (001) substrates. The interpretation of th e diffraction profiles has been carried out with a computer simulation model developed in our labs, which allows the calculation of symmetri c and asymmetric reflections regardless of the substrate orientation o r miscut angle. The agreement between the experimental scans and the t heory was very satisfactory in all the samples, which has enabled us t o determine the main structural parameters of the diodes. Asymmetric 2 24+/- reflections on (111)B structures have been simulated for the fir st time. We have also compared the structural parameters obtained by h igh-resolution X-ray diffractometry with the results deduced from phot oluminescence and photocurrent spectroscopies.