Confinement of excitons in spherical quantum dots

Marı́n, J. L.; Riera, R.; Cruz, S. A.

doi:10.1088/0953-8984/10/6/017

Cited by 77 publications

(57 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Since our quantum dot has smaller size and is confined in all three directions, the exciton binding energy can be expected to be much larger than the bulk exciton binding energy in ZnSe. 14, 15 We thus conclude that the observed activation energy is the exciton binding energy in ZnSe quantum dot.…”

mentioning

confidence: 64%

Growth and photoluminescence study of ZnSe quantum dots

Chang

Chieng

Tsai

et al. 2000

Journal of Elec Materi

View full text Add to dashboard Cite

Special Issue Paper 173Quantum dots (QDs) have received much attention because of their potential applications in optical and opto-electronics devices. 1,2 Various ways of producing QDs have been demonstrated. 3-5 Self-organized QDs attracted the most attention because of their nondestructive and non-growth-interrupted nature. InAs quantum dots on GaAs 6 and Ge quantum dots on Si 7 are well-known examples. These quantum dots were found to grow under the Stranski-Krastanov mode: a layer was first grown in two-dimension, and threedimensional islands were formed after some critical thickness was reached. These dots were formed to relax strain energy without creating dislocations between the dots and the underlying layer, and are epitaxially and coherently grown. The fact that the QDs are defect free is an important reason why QDs usually have very good optical properties.Recently, we showed that high quality QDs could be grown in a metal-organic chemical vapor deposition system by controlling the flow duration of the precursors. 8 The basic idea of the approach is to embed QDs directly in another material with wider bandgap but without introducing a two-dimensional layer. To do so, a rough surface was first prepared as a starting layer. QDs were then grown on this rough surface. Dot size was controlled by growth duration. By using this We report detailed photoluminescence (PL) studies of ZnSe quantum dots grown by controlling the flow duration of the precursors in a metal-organic chemical vapor deposition system. The growth time of the quantum dots determines the amount of blue shift observed in the PL measurements. Blue shift as large as 320 meV was observed, and the emission was found to persist up to room temperature. It is found that changing the flow rate and the total number of quantum dot layers also affect the peak PL energy. The temperature dependence of the peak PL energy follows the Varshni relation. From analyzing the temperaturedependent integrated intensity of the photoluminescence spectra, it is found that the activation energy for the quenching of photoluminescence increases with decreasing quantum dot size, and is identified as the binding energy of the exciton in ZnSe quantum dot.Key words: ZnSe, quantum dots, exciton, photoluminescence method, we were able to grow ZnSe QDs with good properties. In this paper, we report detailed photoluminescence (PL) studies of ZnSe quantum dots grown with different growth parameters. The growth time of the QDs determines the amount of blue shift of the PL from these QDs. Blue shifts ranging from 320 meV to 190 meV were observed for growth duration time between 1 s to 5 s and the emission persists up to room temperature. However, for growth time larger than 5 s, only very weak defect-related emission could be detected. The temperature dependence of the peak emission energy was found to decrease with increasing temperature. Effect of the flow rate of the precursor on the blue shift was studied. We found that, with the same growth duration, the smaller the DESe flow...

show abstract

mentioning

confidence: 64%

Growth and photoluminescence study of ZnSe quantum dots

Chang

Chieng

Tsai

et al. 2000

Journal of Elec Materi

View full text Add to dashboard Cite

show abstract

“…These effects cause a marked increase in the electron-hole attraction inside them; in consequence, the correlated electron-hole pairs (excitons) continue to exist even at room temperature. Quantum confinement produces important changes in the optical properties of QDs compared to those of bulk material; Wannier exciton transitions are responsible for many of these changes [2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…He used a single-band effective-mass approximation for the electrons, and the confinement potentials for the hole and electron were modeled as spherically symmetric potential wells with a finite barrier height, finding a high degree of correlation with experimental data. Marín et al [6] used the approximation of the effective mass for a variational method using 1s-hydrogen-like wavefunctions and finite-height potentials for the exciton's confinement and calculated the ground-state energy for the exciton.…”

Section: Introductionmentioning

confidence: 99%

Binding energy of heavy excitons in spherical quantum dots under hydrostatic pressure

Moscoso-Moreno

Franco

Silva–Valencia

2009

Physica Status Solidi (b)

View full text Add to dashboard Cite

The binding energy of heavy hole excitons in a spherical GaAs–Ga1–x Alx As quantum dot under isotropic hydrostatic pressure was calculated using the Hylleraas coordinate system and a variational approach within the approximation of the effective mass. The influences of hydrostatic pressure on the effective masses of the electron and the heavy hole, the dielectric constant and the conduction‐ and valence‐band offsets between the well and the barriers are taken into account in the calculation. The binding energy is computed as a function of hydrostatic pressure, the dot sizes and the Al(x) concentration. The results show that the binding energy derived from exciton increases with the pressure, especially for small quantum dots. Also, we have found that the binding energy increases with the pressure and the concentration for a fixed quantum dot radius, which can be useful for technological applications. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

show abstract

“…The experimental and theoretical work related to the optical and electrical study of the properties of quantum dots modelled as pyramids is intense [4][5][6][7][8]. They have also been modelled as quantum disks [9,10] and spherical quantum dots [11][12][13]. Nevertheless, under certain growing conditions, these quantum dots have proven to have lens shape geometry characterized by a spherical cap [14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Some electronic and optical properties of self‐assembled quantum dots: asymmetries in a lens domain

Aguilar

Meza-Montes

2006

Physica Status Solidi (b)

View full text Add to dashboard Cite

The self-assembled quantum dot with lens domain has rotational symmetry but it is intrinsically asymmetric when the electron moves perpendicularly to its circular base, i.e. along the rotational axis. To characterize this asymmetry, an external electric field is applied along either the positive or negative direction of the rotational axis. We report the different Stark shifts appearing in the spectra as a function of the field intensity for different lens domains. It is shown that for a flat lens domain the asymmetry effects decrease, but even for very flat lenses they can not be approximated by a cylindrical domain. Finally, some optical properties such as the dielectric constant and electroabsorption are studied. Signatures of the energy spectrum reveal in these quantities. The importance of considering the proper lens domain as long as the magnitude and direction field to tune a specific level transition is stressed.

show abstract

Confinement of excitons in spherical quantum dots

Cited by 77 publications

References 24 publications

Growth and photoluminescence study of ZnSe quantum dots

Growth and photoluminescence study of ZnSe quantum dots

Binding energy of heavy excitons in spherical quantum dots under hydrostatic pressure

Some electronic and optical properties of self‐assembled quantum dots: asymmetries in a lens domain

Contact Info

Product

Resources

About