Intense laser field effects on the binding energy of impurities in semiconductors

Abstract

Nonperturbative, accurate variational results for the binding energy of a shallow hydrogenic impurity in a bulk semiconductor irradiated by a high-frequency, intense laser field are presented. It is pointed out that variational results found with $1s$ and $2s$ atomic trial wave functions presented in previous works on this subject are incorrect because these wave functions do not allow the stretching of the electronic cloud along the polarization direction. This is corrected here by choosing appropriate trial wave functions for the ground and first excited states, which resemble those for the $(1s)\ensuremath{\sigma}$ states of the ${{\mathrm{H}}_{2}}^{+}$ molecular ion. Special attention is paid to the limit of large values for the laser-dressing parameter ${\ensuremath{\alpha}}_{0}$, where our model furnishes almost exact results. In this limit, we found that the binding energy tends to $\ensuremath{-}1∕4\phantom{\rule{0.3em}{0ex}}{\mathrm{Ry}}^{*}$ with the increase of ${\ensuremath{\alpha}}_{0}$. Then, impurity stability against ionization is expected, which is in contrast to previous works.