PREPARATION AND SOME PHYSICAL PROPERTIES OF ZNGEP

Single crystal ZnGeP2 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 ZnGeP2 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 ZnGeP2 is always p‐type. Minority carrier studies point to an electron mobility between 103 and 104 cm2/Vs. Photoconductivity and optical absorption measurements lead to the conclusion that the direct energy gap in ZnGeP2 is 2.25 eV. Copyright © 1969 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim