Investigation of the optical properties of CdZnTe by IR transmission and PL spectra

The optical properties of CdZnTe crystals grown by vertical Bridgman method were investigated in detail by infrared (IR) transmission spectra and photoluminescence (PL) spectra. IR transmission measurements showed that according to the trends of the IR transmission with the wavenumbers, IR transmission spectra could be classified into four types, i.e. descending, ascending, low straight and high straight. Each of them indicated one type of CdZnTe crystals with specified properties. PL measurements revealed that the low-temperature PL spectra consisted of three emissions: the near-band-edge emission (I₀) situated at 1.66eV related to the free and bound excitons, the donor-acceptor emission (I₁) centered at 1.62eV related to the impurities, and a defect band emission (I₂) centered at 1.50eV due to the dislocations. The full width at half maximum (FWHM) of I ₀ and the PL intensity ratios of I₁/I₀ and I₂/I₀ could be used to evaluate the properties of the crystals.