Fine structural properties of ZnSe

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-Znse strained-layer superlattices grown onGaAs (100) substrates by MOCVD were investigated by high resolution transmission electron microscope. Examination of the type and distribution of the defects has revealed that the appearance of defects has relation with the quality of buffer layer. The superlat-tices material that have smooth structure has been prepared by improving the composition of the buffer layer and the thickness of each layer of the superlattice.The superlattice quality was intensely dependent on the substrate surface and buffer layer surface. The superlattice grown on smooth buffer layer has smooth surface

and grown on poor buffer layer has poor quality

and has more defects.The critical layer thickness of ZnS epitaxy grown on smooth GaAs substrate is 2nm

it is slightly bigger than that theortically.The crystalline defects are found to be concentrated in the ZnS layers. It is found that mainly

the ZnS lattice constants change to match with the ZnSe lattice.The imperfection of superlattice structure also shows that there exists a great number of interface steps that make sublattices suspended.In atmospheric pressure growth the interface of ZnSe and ZnS layer exists some deep mutual diffused layer that makes the interface lattice image vague and

indistinct.