Investigation of Te inclusions in CdZnTe crystalline material using Raman spectroscopy and IR techniques
IR images reveal that Te inclusions exist in CdZnTe crystal in the form of square, hexagonal and triangular shapes. The density of Te inclusions for sizes above 5 μm sharply varied from 2.27 × 103 cm−2 to 4.52 × 105 cm−2 with a consequent reduction in IR transmittance from ∼60.5% to ∼55% when the Te-rich volume increased to 83 ppma. Raman spectra suggested that the origin of a new peak at 262.5 cm−1 could be a secondary phonon with A1 symmetry and E symmetry of Te inclusions. The peaks of triangular Te inclusions in Te-rich CdZnTe wafers were shifted to high energy, suggesting that compressive stress existed around the Te inclusions.
Fig. 1. Raman scattering spectra of CZT crystals grown under different Te-rich volume conditions.