Related papers: Direct bandgap optical transitions in Si nanocryst…
We propose a novel concept of achieving silicon quantum dots with radiative rates enhanced by more than two orders of magnitude up to the values characteristic for direct band gap semiconductors. Our tight-binding simulations show how the…
Band gap modification for small-diameter (1 nm) silicon nanowires resulting from the use of different species for surface termination is investigated by density functional theory calculations. Because of quantum confinement, small-diameter…
Elucidating the underlying principles behind band gap engineering is paramount for the successful implementation of semiconductors in photonic and optoelectronic devices. Recently it has been shown that the band gap of a wide and direct…
A high quality amorphous silicon (a-Si) nanostructures has grown experimentally to study the origin of light emission and the quantum confinement effect in a-Si. The quantum confinement effect increases the band gap of material as the size…
We present a theoretical study of Ge-core/Si-shell nanocrystals in a wide bandgap matrix and compare the results with experimental data obtained from the samples prepared by co-sputtering. The empirical tight-binding technique allows us to…
Silicon's inherently indirect bandgap severely limits its radiative efficiency, posing a fundamental challenge to the development of practical silicon-based light sources. While strategies such as nanoscale confinement of electrons and…
A new analytical expression for the size-dependent bandgap of colloidal semiconductor nanocrystals is proposed within the framework of the finite-depth square-well effective mass approximation in order to provide a quantitative description…
We have proposed and validated an ansatz as effective potential for confining electron/hole within spherical quantum dot in order to understand quantum confinement and its consequences associated with energy states and band gap of Spherical…
The effect of quantum confinement in the optical absorption spectra of atomically thin {\alpha}-In2Se3 crystals is studied, observing a huge thickness-dependent shift in the optical band gap of exfoliated {\alpha}-In2Se3 flakes. The band…
Silicon photoluminescence and lasing have been critical issues to breakthrough bottlenecks in the understanding of luminescence mechanisms. Unfortunately, long-standing disputes about the exciton recombination mechanism and fluorescence…
We present quantum-mechanical theory of impact ionization in semiconductors with the direct band gap in \$\Gamma\$-point. It is shown that energy dependence of the impact ionization rate \$\mathcal{W}(E)\$ near a threshold \$E_{th}\$ is…
The atomic and electronic structure of a set of pristine single wall SiC nanotubes as well as Si-substituted carbon nanotubes and a SiC sheet was studied by the LDA plane wave band structure calculations. Consecutive substitution of carbon…
Embedded Si and Ge nanocrystals (NCs) in wide band-gap matrices are studied theoretically using an atomistic pseudopotential approach. From small clusters to large NCs containing on the order of several thousand atoms are considered.…
The redshifts and asymmetric broadening observed in nanocrystal Raman Spectra are attributed to the quantum confinement effects by some authors. But others show that they may come from the local heating caused by the incident laser as well.…
The band gaps and spectral shifts of CdS, CdSe, CdTe, AlP, GaP, GaAs, and InP semiconductor clusters are calculated from band structure calculations using accurate local and non-local empirical pseudopotentials. The effect of spin-orbit…
A modified phonon confinement model considering the size distribution, an improved phonon dispersion curve and a confinement function is developed for the calculation of size dependent Raman spectra of the silicon (Si) nanocrystals. The…
In this work we develop a simple theory for the green photoluminescence of ZnO quantum dots (QDs) that allows us to understand and rationalize several experimental findings on fundamental grounds. We calculate the spectrum of light emitted…
Free standing InP quantum dots have previously been theoretically and experimentally shown to have a direct band gap across a large range of experimentally accessible sizes. We demonstrate that when these dots are embedded coherently within…
Two Dimensional (2D) Transition Metal Dichalcogenides (TMDs) possess a large direct band gap which has been experimentally observed to shrink with increasing charge carrier density (doping). The effect has been the subject of theoretical…
We present an experimental investigation of band-gap shrinkage in n-type GaN using photoluminescence spectroscopy, as a function of electron concentration and temperature. The observed systematic shift of the band-to-band transition energy…