Preparation and Some Physical Properties of ZnGeP₂

Abstract

Abstract Single crystal ZnGeP 2 has been prepared by slow cooling from the melt and by vapour transport of the constituent elements in a phosphorus atmosphere. X‐ray powder studies lead to a c/a ratio for the chalcopyrite‐structured ZnGeP 2 of 1.961. Thermal analysis measurements give a phase change at (952 ± 2) °C, probably disordering of chalcopyrite to zinc blende, and congruent melting at 1025 °C. Resistance‐temperature investigations suggest that acceptor levels at 0.10 and 0.62 eV control the free carrier concentration above and below room temperature, respectively. Undoped ZnGeP 2 is always p‐type. Minority carrier studies point to an electron mobility between 10 3 and 10 4 cm 2 /Vs. Photoconductivity and optical absorption measurements lead to the conclusion that the direct energy gap in ZnGeP 2 is 2.25 eV.