Potential well

About: Potential well is a research topic. Over the lifetime, 1430 publications have been published within this topic receiving 30812 citations.

Customizing electron confinement in plasma-assembled Si/AlN nanodots for solar cell applications

Abstract: Size-uniform Si nanodots (NDs) are synthesized on an AlN buffer layer at low Si(111) substrate temperatures using inductively coupled plasma-assisted magnetron sputtering deposition. High-resolution electron microscopy reveals that the sizes of the Si NDs range from 9 to 30 nm. Room-temperature photoluminescence (PL) spectra indicate that the energy peak shifts from 738 to 778 nm with increasing the ND size. In this system, the quantum confinement effect is fairly strong even for relatively large (up to 25 nm in diameter) NDs, which is promising for the development of the next-generation all-Si tandem solar cells capable of effectively capturing sunlight photons with the energies between 1.7 (infrared: large NDs) and 3.4 eV (ultraviolet: small NDs). The strength of the resulting electron confinement in the Si/AlN ND system is evaluated and justified by analyzing the measured PL spectra using the ionization energy theory approximation.

Layered Inorganic/Organic Hybrid (CdSe)n·Monoamine Nanobelts: Controllable Solvothermal Synthesis, Multiple Stage Amine De-Intercalation Transformation, and Two-Dimensional Exciton Quantum Confinement Effect

Abstract: CdSe nanocrystals, including quantum dots and quantum rods, are a research hotspot in nanomaterials. Recently, it has been found that two-dimensional CdSe semiconductor nanobelts show a unique quantum confinement effect owing to their homogeneous nanoscale thickness. In this study, a series of (CdSe)n·monoamine (n = 1, 2, and 4, monoamine = butylamine, hexylamine, and octylamine) layered inorganic/organic hybrid nanobelts was synthesized by the solvothermal method. These hybrids have a lamellar structure with a few inorganic [CdSe] layers and monoamine layers alternatively stacked along the c axis of their crystallites, which exhibit the typical preferred orientation for layered crystallites and isomorphous [CdSe] layers according to their X-ray diffraction patterns. The [CdSe] layer is a contracted (110) superlattice cell of wurtzite (WZ)-type CdSe with unit cell parameter relations of a ≈ √3aWZ and b ≈ cWZ, and a lamellar nanobelt morphology with the [010] growth direction. These ordered hybrids exhibit...

Energy spectrum of strongly correlated electrons and indirect excitons in quantum dots

Abstract: In the limit of strong correlations, we present a general description of finite electron and exciton systems in semiconductor quantum dots or quantum wells with external electrostatic confinement. We are able to analytically obtain the energy spectrum and wave functions which are constructed by exact diagonalization of the Hamiltonian in terms of the N -particle eigenmodes. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

An alternative approach to understand the photoluminescence and the photoluminescence peak shift with excitation in porous silicon

Abstract: There have been many different models proposed for the luminescence in porous silicon (PS), yet it is believed that the quantum confinement effect persists at the absorption. However, from our investigation on both constant and pulsed electrochemically etched silicon (PS), the absence of quantum confinement effect at the absorption has been identified from the close correspondence of photoluminescence excitation (PLE) spectra of PS to the simulated absorption spectrum of an ultrathin silicon film with the bulk optical constants. In the simulation of absorption spectrum, the spectral dependence of reflectivity of the solid, which had been omitted in the traditional analysis of PLE, is considered. Further, although nanocrystallites of silicon are present in the PS matrix, the absence of quantum confinement is explained on the basis of structural characteristics of PS. Following that, many common observations in the luminescence of PS are attributed to the surface states. The blueshift of the PL peak with th...

Strain, luminescence, and electrical properties of Zn1−xMnxS nanocrystalline films prepared on silicon wafers

Abstract: Nanocrystalline Zn1−xMnxS films (0≤x≤0.25) were deposited on silicon wafers at 473 K using a simple resistive thermal evaporation technique. Morphological and structural measurements revealed that all the films investigated were nanocrystalline with a cubic structure. The lattice parameter increased linearly with Mn concentration. The surface roughness of all the films was shown to be in the range 1.2–3.5 nm. A blueshift in the photoluminescence was observed in the films with increasing Mn concentration along with an intense ultraviolet emission and orange-yellow emission, which are ascribed to the quantum confinement effect. The composition had a significant influence on the orange-yellow emission intensity as well as peak positions. The excitation wavelength of all the samples was 330 nm and emission wavelengths were observed around 410–560 nm. The presence of many recombination sites, surface areas, and defect types leads to broad band photoluminescence emission lines instead of sharp bands. The electr...