Simultaneous Effects of External Electric Field and Conduction Band Nonparabolicity on Optical Properties of a GaAs Quantum Dot Embedded at the Center of a GaAlAs Nano-Wire

Abstract

An investigation of the optical properties of a GaAs spherical quantum dot which is located at the center of a Ga1−xAlxAs cylindrical nano-wire has been performed in the presence of an external electric held. The band nonparabolicity effect is also considered using the energy dependent effective mass approximation. The energy eigenvalues and corresponding wave functions are calculated by finite difference approximation and the reliability of calculated wave functions is checked by computing orthogonality. Using computed energy eigenvalues and wave functions, the linear, third-order nonlinear and total optical absorption coefficients and refractive index changes are examined in detail. It is found that (i) Presence of electric field causes both blue and red shifts in absorption spectrum; (ii) The absorption coefficients shift toward lower energies by taking into account the conduction band nonparabolicity; (iii) For large values of electric field the effect of conduction band nonparabolicity is less dominant and parabolic band is estimated correctly; (iv) In the presence of electric field and conduction band nonparabolicity the nonlinear term of absorption coefficient rapidly increases by increasing incident optical intensity. In other words, the saturation in optical spectrum occurs at lower incident optical intensities.

The linear and nonlinear optical properties of an off-center hydrogenic donor impurity in nanowire superlattices: Comparison between arrays of spherical and cylindrical quantum dots

“…Furthermore, Fig. 7 hand, the nonlinear absorption coefficient rapidly increases with the growth of optical intensity for cases with larger dipole matrix elements [37,43] . Therefore, in study of the optical properties of the system the nonlinear term should be taken into account, especially when the incident optical intensity is comparatively strong.…”

Energy states, oscillator strengths and polarizabilities of many electron atoms confined by an impenetrable spherical cavity

“…Technologically, QDs have many potential applications in microelectronic and optoelectronic devices. In this respect, by employing different approaches and potential shapes, many researchers have studied the electronic structure [2–5], binding energies [6–8], optical properties [9–15], electric and magnetic field effects [16–25], and other physical properties [26–30] of single electron QDs. As well known, it is easy to obtain analytical solutions for single electron QDs.…”

Energy states, oscillator strengths and polarizabilities of many electron atoms confined by an impenetrable spherical cavity

“…Technologically, QDs have many potential uses in microelectronic and optoelectronic devices. In this respect, by employing different approaches and potential shapes, some researchers have studied the electronic structure, [2][3][4][5] binding energies, [6][7][8] optical properties, [9][10][11][12][13][14][15] electric and magnetic field effects, [16][17][18][19][20][21][22][23][24][25] and other physical properties [26][27][28][29][30] of single electron QDs. As well known, it is easy to obtain analytical solutions for QDs with one electron.…”