Binding Energies of Hydrogen-like Impurities in a Semiconductor in Intense Terahertz Laser Fields

We present a detailed theoretical study of the influence of linearly polarized intense terahertz (THz) laser radiation on energy states of hydrogen-like impurities in semiconductors. The dependence of the binding energy for ground (1s) and first excited (2s) states, E1s and E2s, on the intensity and the frequency of the THz radiation has been examined for a GaAs-based system. It is found that E1s, E2s and E2s-E1s decrease with increasing radiation intensity or with decreasing radiation frequency, which implies that an intense THz field can enhance ionization of dopants in semiconductors. Our analytical and numerical results show that one of the most important results obtained by A. L. A. Fonseca et al. [Phys. Stat. Sol. (b)186, K57 (1994)] is incorrect.