Correlation between the low-temperature PL spectra and Cd _0.9Zn_0.1Te quality

The low-temperature photoluminescence (PL) measurements revealed that Cd_0.9Zn_0.1Te PL spectra consisted of three regions: the near-band-edge region with an emission peak I₀ situated at 1.66 eV related to the free and bound excitons, the donor-acceptor region with an emission peak I₁ centred at 1.62 eV related to the impurities, and a defect-band region with an emission peak I₂ centred at 1.50 eV due to the dislocations. The near-band-edge region was dominated by the donor bound exciton peak (I₀) for high-quality Cd_0.9Zn _0.1Te, but dominated by the acceptor bound exciton peak for low-quality Cd_0.9Zn_0.1Te. For all high- and low-quality Cd_0.9Zn_0.1Te, the full width at half maximum of I ₀ can be used to evaluate the overall quality of the crystal, and the PL peak intensity ratios of I₁/I₀ and I ₂/I₀ could be employed to reflect the impurity concentration and dislocation density of the crystal, respectively.