Reduction of the extended defect density in molecular beam epitaxy grown ZnSe based II-VI heterostructures by the use of a BeTe buffer layer

The reduction of extended defects in ZnSe based II-VI heterostructures grown by molecular beam epitaxy on (001) GaAs is reported, using BeTe buffer layers as a novel approach. After defect selective chemical etching three different types of etch pits could be observed by optical microscopy. By the application of a thin BeTe buffer layer the density of paired Frank type stacking faults could be strongly reduced to values below 103 cm−2. The role of Se in the background pressure for the defect nucleation at the II-VI/GaAs interface is significant. It has been found that BeTe can form a smooth interface to GaAs and ZnSe which is reflected in high resolution x-ray diffraction data.