Investigation of D^– centers confined by spherical quantum dots

Abstract

A negative donor center D– in a spherical Gaussian potential quantum dot is studied. The calculations have been performed by means of the exact diagonalization of the Hamiltonian matrix within the effective‐mass approximation. The dot‐radius and confinement‐height dependences of the binding energies of the D– center are obtained. We find that the stability of the D– center strongly depends on the dot radius and the depth of the confining potential. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Binding energy of an off-center shallow donor in a spherical quantum dot

“…This result is in qualitative agreement with previous works that treated on-center D − donors [10,14,17]. It should be mentioned, however, that they differ from a recent calculation by Xie [16]. At small distances from the potential center (d = 0.3a D ), the maximum is less pronounced and there is a minimum at R c .…”

“…The binding energy [10] and the energy levels of the ground and the excited states of spin-singlet and spin-triplet configurations have been calculated variationally by assuming a square finite-well confining potential [11]. Since the experimental demostration of the existence of built-in D − centers in doped multiple quantum wells structures [12], a number of works considered the binding energy of on-center negatively charged impurities, under different confining potentials [13,14,15,16,18]. Xiew proposed a procedure to calculate energy spectrum of D − centers in disk-like QDs with a parabolic lateral confining potential.…”

“…[15]. Recently Xie calculated the binding energy of an on-center D − donor in a Gaussian potential [16] and Sahin showed that the use of the exchange and correlation potential is necesary, within the the local density approximation of density functional theory, for obtaining correct results [17]. In Ref.…”

The second and third-harmonic generation of modified Gaussian quantum dots under influence of polaron effects

“…Examples of these models are parabolic potential [11], Tietz potential [12] and asymmetrical Gaussian potential and spherical potential [13]. In addition, Adamowski et al [14,15] and Xie [16,17] considered a new confinement potential in quantum dots which is called the spherical Gaussian potential. Also, Ciurla et al [18] proposed a new class of the confinement potentials, called the power-exponential potentials.…”

Negative-donor centers and absorption spectra of quantum dots

“…A negative-donor center is analogous to the H − ion, which offers an interesting example of a few-particle system where the electron-electron correlation plays a decisive role in trapping and keeping of a second electron [2]. Since the existence of D − centers in center-doped GaAs/Al x Ga 1−x As multiple quantum wells (QWs) was first reported by Huant et al [1] in 1990, many experimental [3][4][5] and theoretical [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] investigations for D − centers in QWs, and quantum dots (QDs) with and without magnetic fields have been carried out. Much of this work has concentrated on GaAs/GaAlAs structures; particularly on isolated nanostructures subjected to an external magnetic field directed perpendicular to the heteroplanes.…”