Search

Chalcopyrite of CdGeAs 2 single crystal was grown by a modified vertical Bridgman method with sufficient size and quality, and its optical, electrical and thermodynamic properties are characterized. The transmission is recorded in the 2.3–18 μm range, and the band-gap at room temperature is at 0.56 eV. Non-ideal transparency near 5.5 μm which limited its application severely exists in the front of the crystal. The crystal is p type at room temperature with hole concentrations varying from 10 14 to 10 16 cm −3 . From the results of X-ray diffraction measurements carried out over the range 25–450 °C and thermal dilatometer tests, the thermal expansion coefficients are evaluated. And on this basis the Grüneisen parameters at different temperatures are evaluated and also exhibit anisotropic behavior ( γ a > γ c ). It is found that γ a , γ c , and γ V have some difference between these two kinds of test methods. Using these Grüneisen parameters, lattice thermal conductivities have been deduced by two correction formulas. Meanwhile, specific heat capacity and thermal conductivity of [204] have been obtained as a function of temperature by experiment. [ABSTRACT FROM AUTHOR]

• CGSim numerical simulation is employed for Φ60 mm ZnGeP 2 growth. • The constructed numerical model can make qualitative and accurate prediction. • Optimal parameters are obtained to guide experimental growth of Φ60 mm ZnGeP 2 crystal. The mid-infrared nonlinear crystals have shown great promise for the usage in the fields of sum frequency generation, optical parametric amplifier and optical parametric oscillator. These motivations are empowered by high-quality ZnGeP 2 optical devices with high second-order dielectric susceptibility, thermal conductivity and hardness. However, the rapid development of large-sized ZnGeP 2 single crystals with high optical quality is limited by traditional time-consuming and unpredictable growth route. Herein, for the first time, a strategy of comprehensive unsteady computer modeling is implemented to stimulate the Vertical Bridgman growth process of large-sized ZnGeP 2 single crystal by the Crystal Growth Simulator (CGSim) software. The accurate simulations of temperature field, crystal growth rate, crystallization interface shape and thermal stress evolution are achieved by using this established numerical model. The accuracy and feasibility have been confirmed by the agreement between stimulated and experimental results of the temperature field curves and crystallization interface shape. The optimal parameters for growing large-sized (Φ = 60 mm) ZnGeP 2 single crystal are determined: pulling speed of 0.3 mm/h, temperature gradient of 5 K/cm and slow cooling regime. The large-sized (Φ = 60 mm) ZnGeP 2 single crystal with better quality is thus successfully obtained in the crystal-growth experiment in our lab, further verifying the accuracy of the constructed numerical model. Our work provides a new way to predict and guide the growth of large ZnGeP 2 single crystal and other similar single crystals. [ABSTRACT FROM AUTHOR]