The Dependence of Confinement Energy on the Size of Quantum Dots

Ikeri, H. I.; Onyia, A. I.; ., .; Vwavware, O. J.

doi:10.26438/ijsrpas/v7i2.2730

Cited by 12 publications

(6 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Quantum dots can be described as semiconductor nanoparticles in which electrons are bound in all three directions. The process of trapping charge carriers in quantum dots leads to volume quantization, and this has important implications for the absorption and emission spectra that shift to short a wavelength as the size of the quantum dot decreases, this means that large quantum dots produce red a light while small quantum dots produce blue light thus the energy gap is tunable by changing the size of the quantum dots (QDs) based on the quantum confinement effect [9]. The equation for the quantum confinement energy for the ground state of quantum dots is given [10]:…”

Section: The Effect Of Particle Size On Quantum Confinement Energymentioning

confidence: 99%

Effects of Quantum Confinement Energy on the Transmittance of Cadmium Telluride (CdTe) Within the Near Infrared Region (700-2500nm)

Asal,

Al-Rashid

2023

East Eur. J. Phys.

View full text Add to dashboard Cite

This study investigates how the energy of quantum confinement affects the transmittance of cadmium telluride, because of the importance of this substance, as it crystallizes in the form of cubes as thin films that are used in solar cells and liquid crystal imaging devices, as well as in infrared optics [1]. The MATLAB computer program version (2012a) was used, which is based on the characteristic matrix theory and Brus model, in addition to the quantum confinement energy equation. We found that the transmittance value of the nano CdTe thin film at normal incidence reaches 96.4% at a quantum confinement energy Eco = 2.7eV and at a particle size PS =2.6nm, while the value reaches 73.6% at a quantum confinement energy Eco = 0.01eV and at a particle size of PS=50nm.

show abstract

Section: The Effect Of Particle Size On Quantum Confinement Energymentioning

confidence: 99%

Effects of Quantum Confinement Energy on the Transmittance of Cadmium Telluride (CdTe) Within the Near Infrared Region (700-2500nm)

Asal,

Al-Rashid

2023

East Eur. J. Phys.

View full text Add to dashboard Cite

show abstract

“…The natural spatial range over which the confinement emerges is described by the material natural exciton Bohr radius of the bulk matter or de Broglie wavelength of conduction band electron [26]. [27] We recall that the confinement energy of the particle confined in 1D well of width L is expressed as…”

Section: Theoretical Frameworkmentioning

confidence: 99%

Hot carrier exploitation strategies and model for efficient solar cell applications

Ikeri¹,

Onyia²,

Kalu³

2021

View full text Add to dashboard Cite

Hot carriers are electrons or holes that are created in semiconductors upon the absorption of photons with energies greater than the fundamental bandgap. The excess energy of the hot carrier cools to the lattice temperature via carrier–phonon scattering and wasted as heat in [the] picoseconds timescale. The hot-carrier cooling represents a severe loss in the solar cells that have significantly limits their power conversion efficiencies. Hot carrier solar cells aim to mitigate this optical limitation by effective utilization of carriers at elevated energies. However, exploitation of hot carrier energy is extremely challenging as hot carriers rapidly lose their excess energy in phonon emission and therefore requires a substantial delay of carrier cooling in absorber material. In this paper a simple model was formulated to study the kinetic energies and hence the energy levels of the photo excited carriers in the quantum dots (QDs) whereas Schaller model was used to investigate the threshold energies of considered QDs. Results strongly indicate low threshold photon energies within the energy conservation limit for PbSe, PbTe, PbS, InAs, and InAs QDs. These materials seem to be good candidates for efficient carrier multiplication. It is found also that PbSe, PbTe, PbS, InAs, ZnS and InAs QDs exhibit promising potential for possible hot carrier absorber due to their widely spaced energy levels predicted to offer a large phononic gap between the optical and acoustic branches in the phonon dispersion. This in principle enhances phonon bottleneck effect that dramatically slows down hot carrier cooling leading to retention of hot carriers long enough to enable their exploitation. Two novel strategies were employed for the conversion of hot carriers into usable energies. The first approach involves the extraction of the energetic hot carriers while they are ‘hot’ to create higher photo voltage while the second approach uses the hot carrier to produce more carriers through impact ionization to create higher photo current. These mechanisms theoretically give rise to high overall conversion efficiencies of hot carrier energy well above Shockley and Queisser limit of conventional solar cells.

show abstract

“…Here L is the length of the confinement region, m is the mass of the particle, h is the planck constant and n is the quantum number that labels the different confined energy levels of the particle in the well. In general, charge carriers (electrons and holes) in a semiconductor nanocrystal are confined in all spatial 3D [21]. So we considered these charge carriers trapped in an infinite 3-dimensional potential well.…”

Section: Fundamental Conceptmentioning

confidence: 99%

Surface and Quantum Effects in Nanosized Semiconductor

Onyia¹,

Ikeri²,

Chima³

2020

NANO

View full text Add to dashboard Cite

Novel properties of nano-scale semiconductors based on the surface and quantum effects have been studied and applications identified. Spherical potential well model is used to study quantum effect whereas basic geometrical models are used for the surface effect. We have shown such effects to be the fundamental factors responsible for the novel nanosized semiconductor characteristics different from the bulk of same material. It is found that the surface area to volume ratio follows inverse power law. Thus at nanoscale, the surface to volume ratio increases significantly to enhance chemical reactivity. In addition, the increased surface area makes most nananocrystals highly soluble in liquid and dramatically lowers their melting temperature. The result strongly suggests also that the shape of the nanoparticles influences the surface area which has huge impact on their properties and performance. Our results of quantum size effect reveal that spatial confinement of charge carriers within semiconductor nanocrystals significantly modulates their properties such as size dependent absorption and emission spectra with non-zero discrete electronic transition energies as well as their blue shift band gaps. Thus by changing the size of the particle, we can literally fine-tune a material property of interest such as optical, electrical, and surface area. Specifically we found that InAs and InSb nano semiconductor optical absorption spectrum, in contrast to their bulk, can be tuned in broad range of UV to IR regions which are favorable operating wavelengths for nano photonic technology such as IR photo detectors and full spectrum solar cells applications.

show abstract

The Dependence of Confinement Energy on the Size of Quantum Dots

Cited by 12 publications

References 6 publications

Effects of Quantum Confinement Energy on the Transmittance of Cadmium Telluride (CdTe) Within the Near Infrared Region (700-2500nm)

Effects of Quantum Confinement Energy on the Transmittance of Cadmium Telluride (CdTe) Within the Near Infrared Region (700-2500nm)

Hot carrier exploitation strategies and model for efficient solar cell applications

Surface and Quantum Effects in Nanosized Semiconductor

Contact Info

Product

Resources

About