5 research outputs found
Two-subband electron transport in nonideal quantum wells
Electron transport in nonideal quantum wells (QW) with large-scale variations
of energy levels is studied when two subbands are occupied. Although the mean
fluctuations of these two levels are screened by the in-plane redistribution of
electrons, the energies of both levels remain nonuniform over the plane. The
effect of random inhomogeneities on the classical transport is studied within
the framework of a local response approach for weak disorder. Both short-range
and small-angle scattering mechanisms are considered. Magnetotransport
characteristics and the modulation of the effective conductivity by transverse
voltage are evaluated for different kinds of confinement potentials (hard wall
QW, parabolic QW, and stepped QW).Comment: 10 pages, 6 figure
Optical absorption and refraction index change of a confined exciton in a spherical quantum dot nanostructure
Electronic energies of an exciton confined in a strained
Zn1−xCdxSe/ZnSe quantum dot have
been computed as a function of dot radius with various Cd content. Calculations have been
performed using Bessel function as an orthonormal basis for different confinement
potentials of barrier height considering the internal electric field induced by the
spontaneous and piezoelectric polarizations. The optical absorption coefficients and the
refractive index changes between the ground state (LÂ =Â 0) and the first
excited state (LÂ =Â 1) are investigated. It is found that the optical
properties in the strained ZnCdSe/ZnSe quantum dot are strongly affected by the
confinement potentials and the dot radii. The intensity of the total absorption spectra
increases for the transition between higher levels. The obtained optical nonlinearity
brings out the fact that it should be considered in calculating the optical properties in
low dimensional semiconductors especially in quantum dots
Nonlinear optical absorption in graded quantum wells modulated by electric field and intense laser field
The laser field dependence of the linear and nonlinear intersubband optical
absorption in a graded quantum well (GQW) under an applied electric field is
investigated in the effective mass approximation. In our calculations, the
position and the magnitude of the linear and total absorption coefficients
depend on the laser parameter and electric field strength. The resonant peak
of total absorption coefficient can be bleached at sufficiently high
incident optical intensities. Such a dependence of the exciting optical
intensity on the external field strengths in GQWs can be very useful for
several potential device applications