Growth and characterization of Cr-doped CdGeAs2 crystal

Cr-doped CdGeAs2 polycrystal was synthesized by a single-temperature region combined with mechanical and temperature oscillation method, and Cr-doped CdGeAs2 single crystal with Φ17 mm × 30 mm was grown by the improved Bridgman method. The crystal structure, electrical properties and doping content of Cr-doped CdGeAs2 were characterized by high-resolution XRD, Hall-effect and ICP, respectively. In the XPS measurement, the high-resolution scanning spectra of the Cr-doped CdGeAs2 crystals were obtained for the first time, and the binding energies of Cr 2p3/2 are 575.44 eV and 576.50 eV, and the binding energies of Cr2p1/2 are 583.06 eV and 585.14 eV by peak separation and fitting. Finally, FTIR was used to characterize the infrared properties of Cd-doped CdGeAs2 crystals. The results show that the transmittance near 5.5 μm increases with a small amount of doping compared to undoped crystal, and reaches a maximum 42% when the Cr content is 0.057%. When the Cr content increases to 0.158%, the transmittance decreases slightly, and while the content reaches 0.324%, the transmittance of the whole wavelengths decreases sharply. Appropriate amount of Cr can reduce the absorption of CdGeAs2 near 5.5 μm, improve its infrared transmittance and broaden its applications.