Terahertz Spectroscopy of Nanostructures

Many of the characteristic energy scales in semiconductor quantum nanostructures such as quantized subband energies are typically between 1 meV and 100 meV. On the other hand, characteristic time scales in nanostructures such as scattering times and tunneling times are typically 0.1-10 ps. All these energy and time scales, if converted to frequencies of electromagnetic radiation, lie in the terahertz (THz) range. Therefore, the investigation of interaction between electrons and THz electromagnetic radiation gives us important information on the electronic states and dynamical transport properties of electrons in quantum nanostructures, which is not accessible by dc transport experiments. In this section, basic techniques of THz spectroscopy are briefly introduced and some recent topics on the THz spectroscopy of quantum nanostructures are discussed.