Growth and polarized Raman spectroscopy investigations of single crystal CdSiP2: Experimental measurements and ab initio calculations

Large crack free single crystals of CdSiP2 with the dimension of 40 mm in length and 8 mm in diameter were grown by vertical Bridgman method. The bonds vibration properties of the CdSiP2 single crystal were investigated by means of polarized micro-Raman spectroscopy and ab initio calculations. The Raman-active modes and IR-active modes were selected in turn. They were definitively assigned in wave number and symmetry based on classical lattice dynamics calculations. The results indicate that the high phonon frequencies mainly arise from the atomic vibrations of the lighter atoms Si or benching/stretching vibrations of PSi bonds; while, the lower frequencies mainly arise from the atomic vibrations of the heaver atoms Cd or the benching/stretching vibrations of PCd bonds. The conclusions may apply to other II-IV-V2 chalcopyrite compounds such as ZnGeP2, CdGeP2, ZnSiP2.