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 relationship between the energy gap and microstructure of anatase is determined and discussed, and the quantum confinement effect is observed that with the increasing grain size of TiO2 thin film, the band gap energy shifts from 3.4 eV to 3.21 eV.
Abstract: TiO2 coatings are prepared on fused silica with conventional electron beam evaporation deposition. After annealed at different temperatures for four hours, the spectra and XRD patterns of TiO2 thin film are obtained. XRD patterns reveal that only anatase phase can be observed in TiO2 coatings regardless of the different annealing temperatures, and with the increasing annealing temperature, the grain size gradually increases. The relationship between the energy gap and microstructure of anatase is determined and discussed. The quantum confinement effect is observed that with the increasing grain size of TiO2 thin film, the band gap energy shifts from 3.4 eV to 3.21 eV. Moreover, other possible influence of the TiO2 thin-film microstructure, such as surface roughness and thin film absorption, on band gap energy is also expected.
101 citations
TL;DR: The results of photoluminescence experiments performed at 2 and 300 K on porous silicon layers with different porosities were obtained by electrochemical dissolution of (100) silicon wafers in hydrofluoric solution.
Abstract: We present results of photoluminescence experiments performed at 2 and 300 K on porous silicon layers with different porosities. The samples are obtained by electrochemical dissolution of (100) silicon wafers in hydrofluoric solution. The energy of the photoluminescence and its variation with porosity are found in good agreement with a theoretical model of quantum confinement in Si quantum wires. Electrons have to be taken into account, but it is shown that this quantum effect is mainly due (≊60%) to the large confinement of holes.
98 citations
TL;DR: The role of surface and deep-level defects on the blue emission of tin oxide quantum dots (SnO₂ QDs) synthesized by the solution-combustion method at different combustion temperatures is reported.
Abstract: This paper reports on the role of surface and deep-level defects on the blue emission of tin oxide quantum dots (SnO2 QDs) synthesized by the solution-combustion method at different combustion temperatures. X-ray diffraction studies showed the formation of a single rutile SnO2 phase with a tetragonal lattice structure. High resolution transmission electron microscopy studies revealed an increase in the average dot size from 2.2 to 3.6 nm with an increase of the combustion temperature from 350 to 550 °C. A decrease in the band gap value from 3.37 to 2.76 eV was observed with the increase in dot size due to the quantum confinement effect. The photoluminescence emission was measured for excitation at 325 nm and it showed a broad blue emission band for all the combustion temperatures studied. This was due to the creation of various oxygen and tin vacancies/defects as confirmed by x-ray photoelectron spectroscopy data. The origin of the blue emission in the SnO2 QDs is discussed with the help of an energy band diagram.
97 citations
TL;DR: In this article, the ground state energy of an exciton confined to a quantum-well-wire system was calculated as a function of the well's width and depth, using a variational approach.
Abstract: A model calculation is performed of the ground-state energy of an exciton confined to a quantum-well-wire system as a function of the well's width and depth, using a variational approach. The variational wave functions used in the calculation are taken as the product of the appropriate confining Bessel functions and a hydrogenic (exponential) function. For an infinite confining potential well, the binding energy diverges as the well width decreases, while for a finite confining potential well, the binding energy reaches some peak value and then decreases to its value in the bulk material surrounding the wire. It is also shown that the optical absorption coefficient for a quantum-well wire diverges with decreasing wire size when using an infinite-confining-well model. However, for the finite-well model the coefficient reaches a peak value with decreasing wire size, and then drops to its bulk material value.
97 citations
TL;DR: In this paper, the x-ray-absorption spectra of a series of nanodiamond thin films with grain diameters ranging from 3.5 nm to $5\ensuremath{\mu}\mathrm{m}$ at the C $K$-edge using the sample drain current mode at room temperature were measured.
Abstract: This study measures the x-ray-absorption spectra of a series of nanodiamond thin films with grain diameters ranging from 3.5 nm to $5\ensuremath{\mu}\mathrm{m}$ at the C $K$-edge using the sample drain current mode at room temperature. Resonance peaks resembling the C $1s$ core exciton are observed. The exciton state and conduction band edge are found to shift to higher energies with the decrease of the grain size indicative of the presence of the quantum confinement effect.
95 citations