Variation of the Photoionization Cross Section Depending on the Choice of Impurities in the Case of GaAs and CdTe

In this present work, a theoretical study of the variation of the photoionization cross-section, the impact of the vibrational wave functions of the crystal lattice, and the choice of the acceptor nature of some impurities in the case of GaAs and CdTe on this last are carried out. In this work, we added the contribution of overlapping vibrational wave functions to the photoionization of cross section in a polar semiconductor for a charge carrier bound to an impurity. We adopted the Born Oppenheimer approximation to describe the initial state of impurity through a test function and the Lee-Low-Pines function for the final state. Chemical shift, charge carrier-phonon interaction, and central cell correction are taken into account. We used the variational method by minimizing the average value of the energy in order to calculate the binding energy. The behavior of the photoionization cross-section spectra obtained with various frequently used impurities is compared with the experimental and theoretical data. It is observed that the photoionization cross sections increase up to their peaks starting from a quasi-zero value and then decrease as the photon frequency increases. The peaks of the photoionization cross section are almost identical but sometimes shifted. This shows that the vibrational contribution of the crystal lattice is important in the process of calculating the photoionization cross-section. The spectra obtained indicate that the photoionization cross-section is sensitive to the choice and the nature of the impurity.