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.
Optical absorption edges of compound semiconductors in the ZnSiP2-ZnSiAs2 range
Optical absorption edges at 300 K and 80 K have been measured for single crystals of the compounds ZnSiP2, ZnSiP1.5As0.5, ZnSiP1As1, ZnSiP0.5As1.5 and ZnSiAs2. Exponential absorption edge tails were observed in all cases. The minimum energy gap increases from ZnSiAs2 through the range to ZnSiP2; a value of approximately 2.0 eV at 300 K for ZnSiAs2 agrees with previous results, but the value of approximately 2.5 eV for ZnSiP2 is significantly higher than previous measurements.
Epitaxial growth of solid solutions of ZnSiP2 in Si
Abstract A new method of epitaxial growth of some solid solutions between group IV elements and II-IV-V 2 diamond-like semiconductors is described. The method involves traversing an appropriate solvent across a slice of germanium or silicon under a temperature gradient in the presence of the vapour of a II-IV-V 2 compound in a sealed ampoule. The technique has been applied to the growth of solid solutions of Si in ZnSiP 2 with a content of 5% ZnSiP 2 . The best solvents for the liquid zone have been found to be gold and silver.