Using the effective mass approximation, we investigate the photoabsorption and photoelectric process in the conduction band of a single electron charged spherical Si semiconductor quantum dot nanostructure embedded in the amorphous SiO2 matrix. We consider the potential barrier at the interface as of (i) infinite and (ii) finite heights. The effect of self-energy associated with surface polarization due to the charging of the quantum dot is also considered. Our results of photoabsorption coefficient for (1s-1p) transition are found to be in good agreement with the available experimental data.
In this paper we study the linear and nonlinear intersubband optical properties of a nanocrystalline singly charged Si semiconductor quantum dot surrounded by an amorphous matrix of silicon dioxide, silicon nitride, and silicon carbide. A finite barrier height is considered at the interface of the dot and matrix. We also consider the effect of self-energy associated with the surface polarization due to the charging of the dot and the size dependent dielectric constant of the dot. The effect of the surrounding matrix is investigated on the linear and nonlinear absorption coefficient, refractive index changes, nonlinear susceptibility, and photoelectric cross section. Using the effective mass approximation (EMA) results are obtained for different dot radii, photon energies, and intensities. It is noted that an increase in barrier height due to the surrounding matrix leads to blueshift in peak positions of absorption coefficients and refractive index change.
Black phosphorus analogous tin(II) sulfide (SnS) has recently emerged as an attractive building block for photonic and optoelectronic devices due to its intrinsic anisotropic response. Two-dimensional SnS has shown to exhibit in-plane anisotropy in optical and electrical properties. However, the limitations in growing ultrasmall structures of SnS hinder the experimental exploration of anisotropic behavior in low dimension. Here, we present an elegant approach of synthesizing highly crystalline nanometer-sized SnS sheets. Ultrasmall SnS exhibits two distinct valleys along armchair and zig-zag directions due to in-plane structural anisotropy like bulk SnS. We find that in SnS nanosheets, the bandgaps corresponding to two valleys are increased due to the quantum confinement effect. Moreover, the photoluminescence (PL) from SnS quantum dots (QDs) is excitation energy dependent. Our spectroscopic studies infer that PL of SnS QDs originates from the two non-degenerate valleys.
In this work we study the photoabsorption process in a single electron spherical quantum dot of Si embedded in amorphous SiO 2 matrix. We use the effective mass approximation and the energy levels of electron are obtained assuming a spherically symmetric well with infinitely high walls. The results are presented for the energy levels and photoabsorption coefficient for the different sizes of the spherical quantum dot and for various incident photon energies.
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