Topic
Potential well
About: Potential well is a research topic. Over the lifetime, 1430 publications have been published within this topic receiving 30812 citations.
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TL;DR: An efficient synthesis route for highly luminescent silicon nanocrystal (Si-nc) films is presented in this article, where Si-ncs in the films are synthesized in the gas phase by using an argon-silane radio-frequency dielectric-barrier discharge (RF-DBD) plasma.
Abstract: An efficient synthesis route for highly luminescent silicon nanocrystal (Si-nc) films is presented. Si-ncs in the films are synthesized in the gas phase by using an argon-silane radio-frequency dielectric-barrier discharge (RF-DBD) plasma. The size of Si-ncs is well tunable by changing the resident time. The resulting Si-nc films with different oxidation degree exhibit emission across the full visible spectrum. Structural and optical characterization indicates that the red-to-green luminescence from big particles show quantum confinement effect (QCE), while this effect disappears in blue luminescence from small ones. A model is presented to explain this result. In this model, the radiative process in big particles is Band-to-Band recombination, in which surface states have a negligible impact on the QCE, while the blue emission from small Si-ncs is due to the Band-to-Bound recombination, in which surface state plays an important role, resulting in the disappearance of QCE. Additionally, obvious double-exponential decay from midsize particles is observed, in which the two kinds of recombination may coexist.
8 citations
TL;DR: In this paper, the authors calculate one-electron energy levels in potentials derived from the solution of the atomic Thomas-Fermi-Dirac equation using a local exchange potential.
Abstract: We calculate one-electron energy levels in potentials derived from the solution of the atomic Thomas-Fermi-Dirac equation. A local exchange potential is used. Corrections are made to a previous theory, which joins a TFD density to a quantum mechanical electron density near the nucleus, where the Thomas-Fermi-Dirac density has an incorrect singularity. Use of a potential derived from this theory leads to improvement in inner-shell energies. Changes in the potential, suggested in the literature as being reasonable for valence electrons, do not always give the expected improvement. Nor does naively correcting for self-energy lead to improved one-electron energy levels in general.
8 citations
TL;DR: In this article, the Nernst equation is used to quantify changes ΔG° to predict the spontaneity of the reactions in ZnO films and the morphology is investigated by Scanning Electron Microscopy (SEM).
8 citations
TL;DR: In this paper, the authors studied 2D SnTe single crystals with a varied layer thickness as the characteristic length of materials, to eliminate the other coupled effects of interface engineering or universal defects in polycrystalline thin films.
Abstract: There has been emerging research of novel two-dimensional (2D) layered materials recently, due to their striking geometric, electronic and thermoelectric properties caused by the quantum confinement effect. However, the current reported thermoelectric performance of thin films is usually size-sensitive and hence may not be superior to that of their bulk counterparts. It is thus important to determine the size effect for low-dimensional thermoelectric materials, based on the theoretical tools of quantum mechanics. To achieve this goal, we studied 2D SnTe single crystals with a varied layer thickness as the characteristic length of materials, to eliminate the other coupled effects of interface engineering or universal defects in polycrystalline thin films. In this work, we demonstrate that the strategy of the quantum confinement effect is highly sensitive to the layer thickness of 2D SnTe materials, and a critical size of 3 layers exists, above which an abrupt degradation of the mobility and thermoelectric parameters occurs. The thermoelectric performance is optimal in monolayer SnTe and then gradually decays, until 6 layers, which gets close to the bulk feature. Correspondingly, the power factor (PF) and the ZT values exhibit evident layer-tunability as a combined effect of layer-dependent relaxation time, effective mass, electrical conductivity and Seebeck coefficient. Our study provides a profound physical understanding of the low-dimensionality strategy for high-performance thermoelectric materials. The intrinsic thermoelectric properties of ultra-thin 2D materials can be favourable as compared to those of the bulk single crystals.
8 citations
TL;DR: In this article, the average size of the crystallites of CdSe nanocrystals was calculated with the theoretical prediction of the effective mass approximation model (i.e., Brus model), which resulted in that the diameters of crystallites were much smaller than the Bohr exciton diameter (11.2 nm).
Abstract: CdSe/Se multilayer thin films were prepared using sequential thermal evaporation technique by varying the thickness of selenium sublayers. Identifying the prominent peaks observed in the XRD spectra of the top layer CdSe which corresponds to the (100) plane with wurtzite structure, the average size of the crystallites was calculated for the CdSe nanocrystals. Experimentally measured band gaps are larger than bulk band gap of CdSe. This confirms the presence of spin-orbit splitting of energy levels. Size of the crystallites was then calculated with the theoretical prediction of the effective mass approximation model (i.e., Brus model). It resulted in that the diameters of crystallites were much smaller than the Bohr exciton diameter (11.2 nm) of CdSe. Thus the structural and optical properties of CdSe/Se multilayer thin films reveal the effect of quantum confinement of CdSe crystallites in Se matrix for various sublayer thicknesses. Confinement effect is more pronounced while sublayer thickness of selenium increases.
8 citations