Study on the Near-infrared Absorption Properties of ZnGeP2 Single Crystals

Zinc germanium phosphide crystals about 20mm×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 and acceptor defect in ZGP crystals are calculated theoretically. It is found that the influence of acceptor defect on absorption spectra is stronger than that of donor defect.