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: In this article, the authors studied the optical properties of free-standing porous silicon (PS) films during thermal oxidation at 200°C in air by measuring of the PL, IR, optical absorption and Raman scattering spectra.
Abstract: We have systematically studied the evolution of the optical properties of free-standing porous silicon (PS) films during thermal oxidation at 200 °C in air by measuring of the PL, IR, optical absorption and Raman scattering spectra. After thermal oxidation for 200 h, the PL peak energies of free-standing PS films focus on a small energy range centered around 1.61 eV. In this case, a conclusion that the sizes of nanometer silicon particles (NSPs) decrease with increasing time of thermal oxidation is obtained by theoretical fitting for Raman scattering spectra. The evolution of transmission curve is quite complicated (which redshifts first and then blueshifts during thermal oxidation), and can be explained by a model including the quantum confinement effect in the NSPs and the influence of the Si–O bonds on the surface of NSPs. Meanwhile, no focusing of the optical absorption edge of free-standing PS films is found. Experimental results clearly indicate that there is no simple correlation between the PL ene...
16 citations
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TL;DR: The growth mechanisms for the two samples were discussed; this proved that the high coordination ability of ethylenediamine to zinc played an important role in the final phase of the products as mentioned in this paper.
16 citations
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TL;DR: These remarkable results suggest that activators having wide emission bands might be subjected to weak crystal strength via nanostructure materials to modify their electronic transitions and might prove a powerful technique for producing new-advanced materials for use in the fields of solid state lasers and optoelectronic devises.
Abstract: Quantum confinement effect on the energy levels of Eu2+ doped K2Ca2(SO4)3 nanoparticles has been observed. The broad photoluminescence (PL) emission band of Eu2+ doped K2Ca2(SO4)3 microcrystalline sample observed at ∼436 nm is found to split into two narrow well resolved bands, located at 422 and 445 nm in the nanostructure form of this material. This has been attributed to the reduction in the crystal field strength of the nanomaterials, which results in widening the energy band gap and splitting the broad 4f65d energy level of Eu2+. Energy band gap values of the micro and nanocrystalline K2Ca2(SO4)3 samples were also determined by measuring the UV–visible absorption spectra. These values are 3.34 and 3.44 eV for the micro and nanocrystalline samples, respectively. These remarkable results suggest that activators having wide emission bands might be subjected to weak crystal strength via nanostructure materials to modify their electronic transitions. This might prove a powerful technique for producing new-advanced materials for use in the fields of solid state lasers and optoelectronic devises.
15 citations
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TL;DR: In this article, the band-edge exciton fine structure and in particular its exciton and biexciton dynamics in high quality crystals of (PEA)2PbI4 are investigated.
Abstract: Two-dimensional (2D) perovskite materials have recently re-attracted intense research interest for applications in photovoltaics and optoelectronics. As a consequence of the dielectric and quantum confinement effect, they show strongly bound and stable excitons at room temperature. In this report, the band-edge exciton fine structure and in particular its exciton and biexciton dynamics in high quality crystals of (PEA)2PbI4 are investigated. A comparison of bulk and surface exciton lifetimes yields a room temperature surface recombination velocity of 2x10^3cm/s and an intrinsic lifetime of 185ns. Biexciton emission is evidenced at room temperature, with binding energy of about 45meV and a lifetime of 80ps. At low temperature, exciton state splitting is observed, which is caused by the electron-hole exchange interaction. Transient photoluminescence resolves the low-lying dark exciton state, with a bright/dark splitting energy estimated to be 10meV. This work contributes to understand the complex scenario of the elementary photoexcitations in 2D perovskites.
15 citations
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Abstract: In this letter, sol–gel-processed SnO2 films were deposited, with thicknesses varying from 35 to 50 nm, by controlling the concentration of the precursor solutions Through electrical and spectroscopic investigations, it was found that the optical energy bandgap and the electron affinity were affected by the quantum confinement effect and Burstein–Moss effect Moreover, the increased barrier height between Au and SnO2 semiconductors was enhanced when thinner SnO2 layers were used, resulting in strong Schottky diode characteristics This letter allows one to examine the size scaling effects of ultrathin electrical devices with SnO2 channel layers In addition, a generalized energy band diagram derived from the bandgap broadening in ultrathin SnO2 semiconductors is presented, which will allow the elucidation of the carrier transport mechanism and optical properties of quantum confined SnO2 semiconductor-based optical and electrical devices
15 citations