Semiconductor nanotube in strong electrostatic field

Abstract

The states of interacting electron-hole pair in semiconductor nanotube in the presence of strong lateral homogeneous electric field are considered theoretically. It is shown in single-particle approximation that along with the size-quantization of charge carriers’ motion by the radial direction the external strong field leads to the additional (field) localization of particles by the angular variable also. The corresponding additional energy spectrum has an equidistance character. At the same time the strong external field polarizes the electron-hole pair and traps them on the opposite ends of tube’s diameter. Consequently, the excitonic complex with transversal dimensions of the order of the system’s diameter is formed in a nanotube. By using the variation approach, the binding energies and wave functions of first two states of such field excitonlike complex in the tube are also calculated. The electro-optical transitions in the tube without and with the account of electron-hole interaction are considered. It is shown that along with the dependence on the geometric dimensions of the sample and the intensity of the external field, the presence of strong electric field leads also to an explicit dependence of the intensity and the threshold frequencies of absorption on the effective mass of carriers. The resulting field dependence of the optical characteristics of the system can serve as a basis for the direct experimental observation of such excitonlike complexes in semiconductor nanotubes.