Structural properties and relaxation behavior of short-period BeTe/ZnSe superlattices

Transmission and scanning electron microscopy, Nomarski interference light microscopy and atomic force microscopy were applied to study the structural properties of short-period BeTe/ZnSe superlattices (SLs). The relaxation behavior was investigated as a function of the SL thickness for SLs under compressive and tensile stress. The strain state of the SLs is determined by the layer thickness ratio and the chemical bonds (BeSe or ZnTe) at the interfaces. The relaxation of SLs under tensile stress occurs exclusively by cracks. Misfit dislocations are generated in the SLs under compressive stress at thicknesses which significantly exceed the calculated critical thickness.