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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: The temperature and bias dependences of the dark current indicate that the carrier transport mechanism involves percolation hopping, and the spectral response reveals a considerable blueshift in peak energies as the Ge dot size decreases, suggesting that the light absorption originates from the quantum confinement effect of Ge QDs.
Abstract: Metal–oxide–semiconductor (MOS) diodes with zero-, one- or three-layer Ge quantum dots (QDs) embedded in the gate oxide are fabricated for visible to near-ultraviolet photodetection. Ge dots are formed by thermally oxidizing one or three stacks of amorphous Si (a-Si)/polycrystalline-Si0.87Ge0.13/a-Si multi-layers that are sandwiched by SiO2 barriers. The current–voltage characteristics of Ge QD MOS diodes exhibit strong rectification in darkness and feature significant current enhancement in the inversion mode when illuminated. Increasing the number of Ge QD layers from zero through one to three in the gate oxide improves the responsivity from 4.64 through 482 to 812 mA W−1 and enhances the corresponding quantum efficiency from 1.42 through 148 to 245%, respectively. The spectral response reveals a considerable blueshift in peak energies as the Ge dot size decreases from 9.1 to 5.1 nm, suggesting that the light absorption originates from the quantum confinement effect of Ge QDs. The temperature and bias dependences of the dark current indicate that the carrier transport mechanism involves percolation hopping.
27 citations
TL;DR: In this paper, a single-electron transistor based on undoped Si nanocrystals having radii of approximately 3 nm was fabricated and the carrier transport properties observed experimentally have been well understood in terms of carrier tunneling and Coulomb blockade effects.
27 citations
TL;DR: In this article, size-controllable tin oxide quantum dots (SnO2) were prepared by using stannous chloride and thiourea as source materials and the hydrothermal treatment was employed for size control during the self-assembly of SnO2 QDs.
Abstract: Size-controllable tin oxide (SnO2) quantum dots (QDs) in aqueous solution were prepared by using stannous chloride and thiourea as source materials and the hydrothermal treatment was employed for size control during the self-assembly of SnO2 QDs. The size effects on structural and optical properties of QDs were discussed. The prepared QDs were confirmed to be of rutile structure with (2 0 2), (2 1 1) and (3 3 0) facets observed. The crystal lattice constants changed their dimensions during grain growth and secondary grain boundaries appeared if grain size was over 7 nm. The composition and valence states were found independent with grain size. A negative correlation was observed between size and band gap, which exhibited much greater values than the calculation results from the theory of effective mass approximation and illustrated a strong quantum confinement in the present SnO2 QDs. The size effect of photoluminescence property illustrated a fluorescence inhibition, which could be ascribed to the additional energy levels provided by the lattice distortions at secondary grain boundaries. The depletion region in QDs was extended by these defects, which strengthened the quantum confinement effect.
27 citations
TL;DR: In this paper, Al-doped ZnO (AZO) nanoparticles were synthesized by simple wet chemical route and the structure and morphology of the nanoparticles analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed hexagonal wurtzite structure with flower-like clusters consisting of multi-nanorods.
Abstract: The critical role that dopants play in semiconductor devices has stimulated research on the properties and the potential applications of semiconductor nanocrystals. Hence the investigation of the role of dopant concentration on the properties of semiconductor nanoparticles is very important from the viewpoints of basic physics as well as applications. In this context, in the present work Al-doped ZnO (AZO) nanoparticles were synthesized by simple wet chemical route. The structure and morphology of the nanoparticles analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed hexagonal wurtzite structure with flower-like clusters consisting of multi-nanorods. Energy Dispersive Spectrum (EDS) confirms the substitution of Al into ZnO lattice. Defect analysis and excitonic effect of the nanoparticles were investigated by photoluminescence (PL) and UV–Vis absorption measurements, respectively. Optical absorption showed band gap broadening due to quantum confinement effect. PL measurements exhibited both near band edge (NBE) and deep level (DL) emissions. The effect of doping concentration on the growth, crystallization and defect distribution of AZO nanoparticles was studied.
27 citations
TL;DR: In this paper, the structure and composition of the as-prepared nanocrystals were confirmed by scanning electron microscopy, X-ray diffraction, transmission electron microscope and energy dispersive x-ray spectroscopy.
26 citations