Negative donor impurity polarizability and stability in quantum dot under a lateral electric field

Abstract

The binding energies of the ground and excited states of negative (D−) and neutral (D0) donor impurities in a parabolic cylindrical quantum dot (CQD) are calculated within single-band effective mass approximations. The quantum variational method is used to solve the time-independent Schrödinger equation for centered and off-centered impurities under the effect of a lateral electric field. Based on the calculated negative or positive binding energies, the stability of D− and D0 is discussed. The results show that at a specific lateral electric field strength, each D− is switched from a bound (stable) to an unbound (unstable) state in the CQD and differs for centered and off-centered D−. Using the calculated energies and wave functions, the response of the CQD static dipole polarizability (SDP) to the lateral electric field strength is investigated. The results show that CQD size, lateral electric field strength, and lateral electric field direction have a noticeable influence on polarizability. The D− polarizability is found to decrease with increasing lateral electric field strength but shows different behavior with increasing CQD radius.