Partially confined excitons in semiconductor nanocrystals with a finite size dielectric interface

Abstract

The combined effect of finite potential barriers and dielectric mismatch between dot and matrix on excitonic properties of semiconductor quantum dots has been studied. To avoid the unphysical divergence in the self-polarization energy which arises for the simplest and profusely adopted steplike model of the dielectric interface, we proposed a realistic (finite size) smooth profile for the dielectric interface. We have found that the excitonic binding energy can be either higher than the corresponding one to complete confinement by infinite barriers or essentially zero for a wide range of dot sizes depending on the thickness of the dielectric interface. 73.20 Dx,77.55.+f

Three-layer dielectric models for generalized Coulomb potential calculation in ellipsoidal geometry

“…Finally, by using a recursive method in analogy to the analysis of transmission lines [1,4,11,13,[33][34][35][36], those constant expansion coefficients C (l) np and D (l) np can be determined from the following interface conditions for l = 1, 2, . .…”

“…is the Dirac delta function, respectively. Two representative areas of application of such an electrostatic problem include the simulation of semi-conductor quantum dots (QDs) with finite confinement barriers [2][3][4], and the calculation of electrostatic interactions in the so-called hybrid explicit/implicit solvation models for bio-molecular simulations [5].…”

“…As a consequence of using such a three-layer dielectric model, the induced charges are spread along the transition layer and the mathematical divergence in the selfpolarization energy disappears. Moreover, in the case of the spherical geometry, a novel three-layer dielectric model, called the quasi-harmonic model, has been proposed, the corresponding electrostatic problem still admitting explicit analytical series solutions [10,11], while for general three-layer dielectric models several procedures have been developed for solving the problem numerically [4,[11][12][13]. Later, the quasi-harmonic three-layer dielectric model and the robust numerical procedure particularly developed in [11] were extended to the spheroidal geometry [1,14].…”

A consistent extension of the local spin density approximation to account for quantum dot mass and dielectric mismatches

“…31 In order to bypass this drawback, the abrupt mismatch is replaced by a continuous variation of the dielectric constant within a thin layer at the interface with a thickness down to a lattice constant. [31][32][33] In this paper we assume this kind of smooth mismatch for all physical variables involved, namely, effective mass, dielectric constant, and confining potential ͑this last given by the band offset of the adjacent materials͒.…”

Dielectric confinement in quantum dots of arbitrary shape within the local spin density approximation: Diluted regimes in elongated quantum dots

“…The calculation of the selfpolarization potential is really involved, even in the case of electrons confined by finite barriers in spherically symmetric QDs. 11,12 Very recently, a new numerical method revealed good performance extending the calculations to dielectric spheroids. 13 The further extension to axially symmetric QDs, such as lens, cylindrical or ring shaped QDs, has also been published this year.…”