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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 average particle size of Ni-doped CdS nanoparticles was found to lie in the range of 2.7-4nm and the band gap was observed to be 3.79-3.95-eV.
Abstract: Ni-doped CdS quantum dots have been prepared by chemical precipitation technique. The X-diffraction results indicated that the particle size of Ni-doped CdS nanoparticles is smaller than that of undoped CdS and no secondary phase was observed. The average grain size of the nanoparticles is found to lie in the range of 2.7–4 nm. The compositional analysis results show that Cd, Ni, and S are present in the samples. HRTEM studies reveal that the average particle size of undoped and Ni-doped CdS quantum dots is 2 and 3 nm, respectively. Raman spectra shows that 1LO, 2LO, and 3LO peaks of the Ni-doped CdS samples are slightly red shifted when compared to that of undoped CdS. The absorption edge of Ni-doped CdS nanoparticles is found to shift towards the higher-wavelength (red shift) side when compared to that of undoped CdS and the band gap is observed to lie in the range of 3.79–3.95 eV. This band gap is higher than that of the bulk CdS and is due to quantum confinement effect present in CdS nanoparticles.
42 citations
TL;DR: In this article, the synthesis and optical properties of GaAs nanowires with very small diameters were reported, where size-selective gold particles with nominal diameters of 5, 10, 20, 40, and 60 nm were used.
Abstract: We report the synthesis and optical properties of GaAs nanowires with very small diameters. We grew the GaAs nanowires by using size-selective gold particles with nominal diameters of 5, 10, 20, 40, and 60 nm. The diameter-controlled nanowires enable us to observe blueshifts of the free exitononic emission peak from individual nanowires with decreasing gold-particle size due to the two-dimensional radial quantum-confinement effect. We also analyze the absorption and emission polarization anisotropies of these bare GaAs quantum nanowires.
41 citations
TL;DR: In this article, the authors reported well-resolved band edge luminescence with no deep level emissions for Si0.8Ge0.2/Si single quantum well (SQW) structures grown at high substrate temperatures by solid source Si molecular beam epitaxy (MBE).
Abstract: Well‐resolved band edge luminescence with no deep level emissions is reported for Si0.8Ge0.2/Si single quantum well (SQW) structures grown at high substrate temperatures (Ts≊620 °C) by solid source Si molecular beam epitaxy (MBE). No‐phonon (NP) transitions due to symmetry‐breaking alloy disordering in SiGe layers and transverse optical (TO) phonon replicas were clearly identified. With decreasing well width, NP and TO emissions were found to show systematic blue shift due to quantum confinement effect. Excellent crystal quality was evidenced by total absence of defect‐related deep level emissions characteristic of photoluminescence spectra of samples grown at lower temperatures, Ts<600 °C. This result indicates that high growth temperature environment is essential to efficient radiative recombination in SiGe/Si QW structures.
41 citations
TL;DR: In this article, the excited state properties of allylamine-capped silicon quantum dots (SiQDs) from Si10 to Si59 are studied using a density-functional tight-binding method and compared with available experimental data.
Abstract: Excited-state properties of allylamine-capped silicon quantum dots (SiQDs) from Si10 to Si59 are studied using a density-functional tight-binding method and compared with available experimental data. Signatures in vibrational and optical absorption spectra are revealed, which show the detailed effect of modification of the SiQDs with allylamine. It is verified that the modification could be expected to not only reduce the surface oxidation rate but also maintain an efficient electronic transition feature that facilitates blue emission. The optical properties show significant size dependence due to the quantum confinement effect. The increase in the number of allylamine molecules could only result in a slight red shift of emission spectra.
41 citations
TL;DR: In this article, a simple combustion method was used to synthesize Cr-doped SnO2 quantum dots (QDs) with various doping concentration, and the X-ray diffraction patterns revealed that the prepared QDs have monophasic tetragonal rutile-type crystallite structure with an average crystallite size of ∼3nm.
Abstract: Chromium (Cr)-doped SnO2 quantum dots (QDs) with various doping concentration have been successfully synthesized using a simple combustion method. The QDs have been characterized by using various techniques. The X-ray diffraction patterns revealed that the prepared QDs have monophasic tetragonal rutile-type crystallite structure with an average crystallite size of ∼3 nm. The optical band gap energies of QDs increased with increasing the Cr ion concentration. The XPS spectra reveal the presence of Sn4+, Cr3+, and O respectively. Cr (0.03 mol%)-doped SnO2 QDs are exhibited the greater photocatalytic activity compared with other photocatalysts, which is attributed mainly due to quantum confinement effect and an increase in specific surface area. The existence of a Cr3+ as shown from XPS spectra, act as an electron acceptor and/or hole donor, which enhancing longer survived charge carrier separation in Cr-doped SnO2 QDs as confirmed by PL spectroscopy.
41 citations