Absorption of Infrared Radiation by an Electronic Subsystem of Semiconductor Nanoparticles

The frequency dependence of the cross section of photon absorption by semiconductor nanoparticles in the infrared range is considered. Light is absorbed by conduction electrons with plasmon formation and electrons in the traps both within the bulk and on the nanoparticle surface. The regularities of the photoabsorption cross section largely depend on the size of the nanoparticles. For sufficiently large nanoparticles, there appear only two characteristic peaks in the cross section distribution corresponding to light absorption by two types of electrons—conduction electrons and electrons in the volume traps of nanoparticles. The number of electrons trapped on the surface is relatively small, and the electrons do not contribute to the total cross section of photoabsorption. In the case of photon absorption by quantum dots, the contribution of these surface electrons as well as a third peak is evident. This result occurs due to a complex dependence of the number of electrons in the traps on their depth and s...