Electron transport of a quantum wire containing a finite-size impurity under terahertz electromagnetic-field illumination

We investigate theoretically the electron-transport properties for a semiconductor quantum wire containing a single finite-size attractive impurity under an external terahertz electromagnetic-field illumination in the ballistic limit. Within the effective-mass free-electron approximation, the scattering matrix for the system has been formulated by means of a time-dependent mode matching method. Some interesting properties of the electron transmission for the system have been shown through numerical examples. It is found that in the case of a relatively large field amplitude and a frequency resonant with that corresponding to the difference between the two lowest lateral energy levels in the impurity region, the field-induced intersubband transition dominates the process as it does in the absence of the impurity. Furthermore, there is a steplike structure on the transmission as a function of the incident electron energy. However, in the case of a small field amplitude and nonresonant frequencies, both mult...