Study on the Near-infrared Absorption Properties of ZnGeP_2 Single Crystals

Zinc germanium phosphide crystals about φ20mm×90mm were grown by using Bridgman techniques.The three measured crystal sheets with thickness 4.0mm were obtained from the tail,middle and top of single crystal ingot.The infrared absorption properties were studied according to the experimental and theoretical data.The results show that the transmitted intensity gradually increased from top to bottom of ZGP crystals,which is caused by the inhomogeneous distribution of different kinds of intrinsic point defect.The absorption spectra of donor defects GeZn+ and acceptor defect V-Zn in ZGP crystals are calculated theoretically.It is found that the influence of acceptor defect V-Zn on absorption spectra is stronger than that of donor defect GeZn+.