The band structure and optical gain have been calculated for GaInNAs/GaAs quantum wells (QWs) with various nitrogen concentrations within the 10-band and 8-band kp models. Two approaches to calculate optical properties of GaInNAs/GaAs QWs have been compared and discussed in the context of available material parameters for dilute nitrides and the conduction band nonparabolicity due to the band anti-crossing (BAC) interaction between the N-related resonant level and the conduction band of a host material. It has been clearly shown that this nonparabolicity can be neglected in optical gain calculations since the dispersion of conduction band up to the Femi level is very close to parabolic for carrier concentrations typical for laser operation, i.e., 5 × 1018 cm−3. This means that the 8-band kp model when used to calculate the optical gain is very realistic and much easier to apply in QWs containing new dilute nitrides for which the BAC parameters are unknown. In such an approach, the energy gap and electron effective mass for N-containing materials are needed, instead of BAC parameters. These parameters are available experimentally much easier than BAC parameters.

No abstract

No abstract

We performed an extensive numerical study of the linewidth enhancement factor ͑␣-parameter͒ in single and multiple-quantum-well structures built from In 0.38 Ga 0.62 As 1−y N y / GaAs material systems. A ten-band kp Hamiltonian matrix was used in the calculations and solved self-consistently with Poisson's equation. The linewidth enhancement factor was evaluated as a function of wavelength, nitrogen composition, well width, and carrier density and shows significant dependence on those parameters. The simulated results are in good agreement with published experimental data for a single quantum well. We demonstrate that engineering the desired linewidth enhancement factor is possible by varying the aforementioned parameters.

Semiconductor quantum dots (QDs) are the subject of intensive research worldwide due to a number of novel properties, which make them of interest for both fundamental science and technological applications. QDs are of particular interest for solar cell applications due to their ability to increase efficiency via the generation of multiexcitons from a single photon. The efficiency of multiexciton generation (MEG) in colloidal QDs is determined by the competition between MEG and other hot electron-cooling processes. Core/shell QDs with type-II band alignment offers extra degrees of freedom in mediating both the optical dipoles and the Coulomb interaction between charges in such structures for the benefit of elevated MEG efficiency.

Abstract-Semiconductor quantum dots (QDs) are the subject of intensive research worldwide due to a number of novel properties, which make them of interest for both fundamental science and technological applications. QDs are of particular interest for solar cell applications due to their ability to increase efficiency via the generation of multiexcitons from a single photon. The efficiency of multiexciton generation (MEG) in colloidal QDs is determined by the competition between MEG and other hot electron-cooling processes. Core/shell QDs with type-II band alignment offers extra degrees of freedom in mediating both the optical dipoles and the Coulomb interaction between charges in such structures for the benefit of elevated MEG efficiency.Index Terms-Absorption, core/shell, multiexciton generation (MEG), quantum dot solar cells.

No abstract

Articles you may be interested inComparative analysis of quantum cascade laser modeling based on density matrices and non-equilibrium Green's functions Appl. Phys. Lett. 105, 103106 (2014); 10.1063/1.4895123 Non-equilibrium Green's function calculation for GaN-based terahertz-quantum cascade laser structures J. Appl. Phys. 111, 083105 (2012); 10.1063/1.4704389Multiquantum well gain modeling using a Green's function-based fractional dimensional approach