Evaluation of cation ordering in ZnSnP2 via non-polarized Raman spectroscopy

Abstract

Evaluation of the degree of order is a crucial issue for ternary derivatives of III–V and II–IV semiconductors owing to the strong correlation between their optical bandgap and the degree of atomic disorder on the cation sublattice. Although x-ray diffraction techniques have been extensively employed, analysis of oriented samples remains challenging. In this study, we demonstrate that the degree of order in the II–IV–V2 chalcopyrite phosphide ZnSnP2 can be semi-quantitatively evaluated by non-polarized Raman spectroscopy. The sensitivity of the totally symmetric Raman mode to the long-range order parameter is explained through the tetrahedral displacement parameter u, based on the bond polarizability model, directly linking the Raman spectra and cation ordering. The proposed relationship is validated by measurements on both powder and bulk samples with controlled order parameters. These findings highlight the potential of non-polarized Raman spectroscopy as a simple and rapid method for in situ evaluation of cation order in multinary compounds.