Enhanced near-infrared optical transmission in zinc germanium phosphide crystals precise magnesium doping.

A zinc germanium phosphorus (ZnGeP) crystal with a chalcopyrite structure is an efficient frequency converter in the mid-infrared region. However, point defect-induced optical absorption at the pumping wavelength (near infrared region) blocked the further application of ZnGeP. To alleviate the absorption losses caused by point defects, magnesium doping compensation was presented during the ZnGeP bulk crystal growth process the vertical Bridgman method. Combined with theoretical calculations, the structural distortion of the magnesium-doped ZnGeP crystals in different orientations was illustrated. The thermodynamic and kinetic stability of the magnesium-doped ZnGeP structure were demonstrated. The transmission results indicated the improvement of transmittance within a wavelength range of 1.8-2.4 μm when doped with magnesium, which revealed the powerful ability of the appropriate dopant in optimizing near-infrared optical properties. Thus, the introduction of magnesium is a practical approach to improve the transmittance performance and extend the pumping source wavelengths of ZnGeP crystals.