Growth improvement and quality evaluation of ZnGeP2 single crystals using vertical Bridgman method

ZnGeP2 single crystals were grown using two-temperature zone vertical Bridgman method. The effect of crucible material, crucible shape, and cooling program on the growth of the ZnGeP2 crystal was investigated. The qualities of the crystals were evaluated by high resolution X-ray diffraction, X-ray fluorescence spectrometry, and IR transmittance spectra. The results show that the full width at half maximum of the rocking curves for (200), (004), and (220) faces are 45″, 37″, and 54″, respectively. The concentration of the P, Zn and Ge are almost homogeneous along the growth axis, but P and Zn are slightly deficient compared with Ge in the as-grown ZnGeP2 crystals. The increase of annealing temperature from 600 °C to 700 °C has little effect on the reduction of the absorption losses in ZnGeP2 powders, and has negative effect on the reduction of the absorption losses in ZnP2 powders. Annealed in ZnP2 powders at 600 °C for 300 h, the optical absorption loss at 2.05 μm reduce by 37%, compared with that of 27% reduction annealed in ZnGeP2 powders.

► Quartz crucible is favor for nucleation in ZnGeP2 spontaneous growth.
► PBN crucible is favor for the integrity in the seeded ZnGeP2 growth.
► Concentration of the P, Zn, and Ge are almost homogeneous along the growth axis. M025BA; Annealing in ZnP2 powders at 600 °C, the absorption loss at 2.05 μm reduce by 37%.