Binding energy of a hydrogenic impurity in a coaxial quantum wire with an insulator layer

Abstract

The electronic properties of a coaxial cylindrical quantum well-barrier system constituted about an central insulating wire were determined under an external electric field. The model wire, inside to outside, was considered to be layered as AlAs/GaAs/Alx1Ga1−x1As/GaAs/Alx2Ga1−x2As. Within the framework of the effective mass-approximation, the binding energy of a hydrogenic impurity is calculated by using the combination of the fourth-order Runge-Kutta method and variational approaches. The binding energy exhibits sharp changes depending on the impurity position and the geometrical parameters of the structure such as the well widths of the GaAs wires and the height and thickness of the barrier constituted by Alx1Ga1−x1As. The binding energy of the electron was found to be independent from the impurity position for the specific widths of the well wires. Also, the barrier properties appeared as very effective parameters in controlling the probability distribution of the electron.