Quantum-Mechanical Approach to the Description of the Interaction between Microwave Radiation and Conducting Thin Films

A quantum-mechanical approach to analysis of the interaction between electromagnetic radiation and ultrathin conducting films in the frequency range of 1–200 GHz is proposed. It is shown that, at film thicknesses smaller than 10 nm, it is necessary to take into account the symmetry of the conductor atomic lattice, the break of which can lead to an increase in the energy gap between the valence and conduction bands. The resulting band gap strongly affects the conductivity of a thin metallic film and its electrodynamic characteristics under interaction with the microwave radiation. It is demonstrated by the example of aluminum that the face-centered lattice symmetry break leads to the formation of a band gap of about 0.07 eV.