Determination of defect density in ZnCdMgSe layers grown on InP using a chemical etch

ZnCdMgSe epitaxial layers grown on InP (001) substrates have been characterized by etch pit density (EPD) measurements. A hydrobromic acid and acetic acid solution at a concentration of 1:7 by volume was found to work well for the EPD measurements. Atomic force microscopy (AFM) was used to characterize the morphology of the etched surface. The AFM results showed that the etch pit depth became constant after a depth corresponding to roughly the II-VI layer thickness. The accuracy of the etch pit density method for revealing stacking faults and dislocations was verified by plan-view transmission electron microscopy (TEM). Both stacking faults and threading dislocations originating from misfit dislocations were revealed by this etchant. The TEM and AFM results showed that the etching is very selective. We show that we have grown ZnCdMgSe layers with an EPD of ∼106 cm−2.