Interface Diagnostics: Equivalent Circuit Characterization for a Growing Bulk Single Crystal

Despite the Czochralski technology having been commonly used for manufacturing bulk single crystals, crystal quality and production are still limited by the insufficient understanding of the crystal-melt interface. Herein, we propose a novel perspective on the voltammetric characteristics of an equivalent circuit model to reveal a growing boule. Specifically, by elucidating the interface electromotive force during lithium niobate crystal growth, we find the nonlinear conduction behavior at the crystal-melt interface, representing the characteristic of a PN junction. Further regarding this interface as a rectifier diode with parasitic resistance, the volt-ampere curves will draw abundant crystal growth information in situ. For example, the real-time cyclic voltammetry curves are highly consistent with the circuit simulations, whose series resistance well predicts the actual length of the as-grown crystal. More importantly, this equivalent circuit model establishes a simple but effective perspective for revealing the nature of the growth system, encompassing the kinetics of high-temperature phase transition and the thermodynamics of quantitative composition control.