DETERMINATION OF THE RESIDUAL STRAIN BY X-RAY-ANALYSIS IN ZNSE EPILAYERS GROWN ON GAAS(001), GASB(001) AND GASB(111) BY METALORGANIC VAPOR-PHASE EPITAXY

The residual strain in ZnSe epilayers grown on GaAs (001) and successfully on GaSb (001) and GaSb (111) by metalorganic vapor phase epitaxy (MOVPE) is investigated by X-ray diffraction. The substrate's orientation induced that of the layers. Double X- ray diffraction used to characterize the ZnSe/GaAs heterostructures (lattice mismatch 0.27 % ) allows the determination of the crystalline quality of the layers and also the state of the strain. In heterostructures the lattice mismatch and the difference in the thermal expansion coefficients between layer and substrate induced a residual strain in the layer. Both phenomena are observed in ZnSe/GaAs. In ZnSe/GaSb heterostructure there is a lattice mismatch of -7 %. In ZnSe /GaSb (001) a decrease of the strain is observed with increasing layer thickness from 0.4 to 5 mum and is attributed to the relaxation of the thermal strain. For the (111) orientation, a determination of the distance between the (111) planes of the layer is possible and allowed a comparison with the distance of these planes in bulk material. To study the residual strain in epilayers, X - ray diffraction is an accurate, non-destructive and useful method.