Dependence of the optical properties of p-CdTe and p-Cd0.96Zn0.04Te on the bromine concentration in a bromine-methanol etching solution

Photoluminescence measurements were carried out to investigate the dependence of the optical properties of p-CdTe and p-Cd0.96Zn0.04Te on various relative concentrations of bromine in a mixture of methanol and bromine. As the bromine concentration increased, the intensity of the luminescence increased; additionally, an exciton bound to a neutral acceptor (A°X) peak at 1.588 eV in p-CdTe was resolved into an exciton bound to neutral donor (D°X) peak at 1.592 eV and an A°X peak. The mixed bands of the 1.574 and 1.546 eV peaks were well resolved by using an etching bromine concentration of 2%; in particular, the intensities of the D°X and 1.574 eV peaks increased as much as five and seven times, respectively. The intensity of the peak at 1.48 eV related to defects also increased. The intensity of A°X at 1.609 eV in p-Cd0.96Zn0.04Te changed slightly with the bromine concentration. The intensities of the luminescence peaks due to the recombination of the electrons in conduction band with acceptors and to the defect relation did not vary. These results indicated that the number of Cd vacancies could be reduced due to the addition of Zn.