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.
Electron-impact excitation of the hydrogen metastable 2s state to the 3s, 4s, 3d, and 4d states is studied in the presence of a resonant laser field using the rotating-wave approximation. The frequency of the circularly polarized laser field is chosen to match the 2s-3p transition frequency in the hydrogen atom.The role of the laser field in individual magnetic substate (mf =0, +1,+2) excitation is analyzed. It is found that for these optically forbidden transitions (s-s, s-d), a significant increase in the excitation cross sections is obtained through joint collisions with electrons and photons.PACS number(s): 34.80.Qb
In this work we investigate some optical properties of semiconductor ZnO spherical quantum dot embedded in an amorphous SiO2 dielectric matrix. Using the framework of effective mass approximation, we have studied intraband S-P, and P-D transitions in a singly charged spherical ZnO quantum dot. The optical properties are investigated in terms of the linear and nonlinear photoabsorption coefficient, the change in refractive index, and the third order nonlinear susceptibility and oscillator strengths. Using the parabolic confinement potential of electron in the dot these parameters are studied with the variation of the dot size, and the energy and intensity of incident radiation. The photoionization cross sections are also obtained for the different dot radii from the initial ground state of the dot. It is found that dot size, confinement potential, and incident radiation intensity affects intraband optical properties of the dot significantly
The second harmonic generation (SHG) and the sum frequency generation (SFG) processes are investigated in the conduction band states of the singly charged ZnO quantum dot (QD) embedded in the HfO 2 , and the AlN matrices. With two optical fields of frequency ω p and ω q incident on the dot, we study the variation with frequency of the second order nonlinear polarization resulting in SHG and SFG, through the electric dipole and the electric quadrupole interactions of the pump fields with the electron in the dot. We obtain enhanced value of the second order nonlinear susceptibility in the dot compared to the bulk. The effective mass approximation with the finite confining barrier is used for obtaining the energy and wavefunctions of the quantized confined states of the electron in the conduction band of the dot. Our results show that both the SHG and SFG processes depend on the dot size, the surrounding matrix and the polarization states of the pump beams. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.