Chemical analysis of ZnGeP2 as a new line of research of heterogeneity in bulk crystals

► ICP AES method was proposed for examination of heterogeneous bulk ZnGeP2 crystals. ► The stoichiometric ZnGeP2 was used as a standard to correct all statistical errors. ► Heterogeneous ZnGeP2 crystals were analyzed with this standard under the same conditions. ► ZnP2 and Ge phases distributed irregularly in the bulk crystals were determined around 2-7 mol.%.