Intense-terahertz-laser modulated photoionization cross section of shallow-donor impurity in semiconductors in a magnetic field

Abstract

The effects of intense terahertz laser and magnetic fields on the photoionization cross section (PICS) of shallow-donor impurity in semiconductors are investigated within the Faraday configuration. The donor ground-state energy level and its wave function are calculated using a combination of nonperturbative and variational methods where radiation field is exactly included through a laser-dressed Coulomb potential (LdCP). We find that a competition between donor ground-state binding energy and optical integrals in tailoring the magnitudes and peak positions of PICS is achieved by external fields via the LdCP. In this way, the magnitudes and peak positions of PICS can be decreased or increased and effectively tuned with an appropriate choice of external fields. The overall shape of PICS is optically anisotropic, which is more pronounced in the z-polarization direction for large laser field intensity or low magnetic field. In the vicinity of ωc, the overall shape of PICS in the z-polarization direction changes into that of PICS in the x-polarization direction. Our theoretical findings hold promising applications in designing and developing new efficient impurity-based devices manipulated by external fields.

Keywords

• Intense THz laser field
• Photoionization cross section
• Shallow-donor impurity
• Nonperturbative approach