Nanoscale physics

Impurity effect on the spectral parameters of an electron in a quantum dot - quantum ring semiconductor nanostructure
Hnidko I.S., Gutsul V.I., Koziarskyi I.P., Makhanets O.M.
Yuriy Fedkovych Chernivtsi National University, Kotsyubynsky St. 2, Chernivtsi-58002, Ukraine
E-mail: hnidko.ihor@chnu.edu.ua

Multilayer semiconductor nanostructures have been studied both theoretically and experimentally for quite a long time. The unique properties of quasiparticles in such systems make it possible to use them as basic elements in devices of modern nanoelectronics: tunnel nanodiodes, nanolasers, nanodetectors [1, 2].
In this work, we investigate a nanostructure consisting of a cylindrical semiconductor quantum dot (quantum well, GaAs medium), which through a finite potential barrier (AlxGa1–xAs medium) is tunnel-connected to a coaxial cylindrical nanoring (quantum well, GaAs medium). The donor impurity is located on the axial axis of the nanostructure. It creates an attractive Coulomb potential for an electron.
The calculation of the energy spectrum and wave functions of the electron was performed in the model of effective masses and rectangular potential energies. The stationary Schrödinger equation for an electron interacting with an impurity cannot be solved analytically exactly. Therefore, the electron spectrum was found by the method of expansion the unknown wave function of a quasiparticle with a complete orthonormal set of electron wave functions in a nanostructure without impurity and subsequent solution of the obtained secular equation.
The dependence of the electron energy spectrum and the oscillator strengths of intraband quantum transitions on the geometric characteristics of the nanostructure is theoretically investigated. All these dependences are complicated and non-monotonous, due to the complicated nature of the density distribution of the probability of location of electron which is interacting with impurity in nanosructure..

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