Single crystal growth and phase stability of photovoltaic grade ZnSiP2 by flux technique

ZnSiP₂ is a potential optoelectronic material with possible application in lasers, LED´s, photonic integrated circuits, and photovoltaics. The development of ZnSiP₂ as a photovoltaic material could address the current technological challenge of implementing a monolithic top cell on silicon for tandem photovoltaics. In this work we present a detailed description of the growth of ZnSiP₂ single crystals, which has enabled thorough optoelectronic characterization. A flux growth technique was used, under various conditions, to grow ZnSiP₂ single crystals in Zn solution. The results of these growth experiments, along with analysis of previously determined phase diagrams, show that three secondary phases form as a result of the Zn flux growth technique: Zn₃P₂, Si, and the remaining Zn flux. Potential reasons for the formation of these particular phases are discussed, but their presence is found to be non-detrimental, and they can easily be removed. The resulting single crystals are high purity and enable the characterization of the fundamental optoelectronic properties of ZnSiP₂.