Strain determination in PbEuTe/PbTe multi-quantum wells

A series of Pb1-xEuxTe/PbTe multi-quantum well (MQW) samples were grown on (111) cleaved BaF2 substrates by molecular beam epitaxy. The Eu content was maintained at x similar to 0.05-0.06 and the PbTe well width was varied fr om 23 to 206 Angstrom. The samples were characterized structurally by high resolution x-ray diffraction in the triple axis configuration. The omega/2 Theta scans of the (222) Bragg reflection showed very well resolved satelli te peaks up to the tenth-order for all samples indicating that sharp interf aces were obtained. Reciprocal space mapping around the (224) lattice point indicated that the MQW structure tended to the free-standing condition. Th e (222) omega/2 Theta scans were calculated by dynamical theory of x-ray di ffraction and compared to the measured ones. Using the in-plane lattice con stant as the main fitting parameter, the strain in the PbTe well inside the MQW structure was obtained as a function of its width. It decreased monoto nically from an almost fully strained layer to 26% of strain relaxation as the PbTe well increased from 23 to 206 Angstrom. (C) 2000 American Institut e of Physics. [S0021-8979(00)06414-8].