Different quantum behavior of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="italic">E</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="italic">E</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>spectral structures in

Tognini, P.; Andreani, Lucio Claudio; Geddo, M.; Stella, A.; Cheyssac, P.; Kofman, R.; Migliori, A.

doi:10.1103/physrevb.53.6992

Cited by 69 publications

(39 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Comparison between the oneparticle theoretical optical spectra and experimental results from ref. [6] for the Ge dots can be evaluated expanding the one-particle wave functions in terms of the atomic orbitals of the tight-basis w a c a f a , where a is the index of the atomic orbitals.…”

Section: Calculation and Resultsmentioning

confidence: 99%

Optical Properties of Germanium Nanocrystals

Palummo

Onida

Sole

1999

phys. stat. sol. (a)

View full text Add to dashboard Cite

We study the electronic structure and the optical properties of germanium clusters up to about 103 atoms, by using a semi‐empirical tight‐binding approach. Germanium nanocrystals are related to quantum dots growing, by a self‐organization process, in sapphire matrices. The optical properties of such dots are experimentally found to be strongly influenced by quantum confinement effects. We investigate these effects from the theoretical point of view, calculating the optical spectra in the single‐particle approximation. Inclusion of the electron–hole interaction is found to yield visible effects.

show abstract

Section: Calculation and Resultsmentioning

confidence: 99%

Optical Properties of Germanium Nanocrystals

Palummo

Onida

Sole

1999

phys. stat. sol. (a)

View full text Add to dashboard Cite

show abstract

“…In the case of semiconductor nanostructures, one would expect the interband transitions to move to higher energies due to QC effects. The blue shift of these transition energies in Si and Ge NCs has been studied mostly by optical spectroscopies [87][88][89][90], but ambiguous results were obtained because the information they yield is difficult to interpret due to several factors contributing to the experimental results: size dispersion of NCs, different shapes, density and interface structures of NCs as well as electron, photon and phonon transfer between NCs. The local information obtained directly in individual NCs by STEM-EELS is somewhat simpler to understand and interpret.…”

Section: Kepaptsoglou Electron Microscopy Course 2011)mentioning

confidence: 99%

Direct observation of quantum confinement of Si nanocrystals in Si-rich nitrides

et al. 2012

View full text Add to dashboard Cite

In the past years, a large body of work has been dedicated to semiconductor quantum dots embedded in thin films of oxide and nitride, as the tailorable electronic and optical properties of these nanostructures make them desirable for various optoelectronic applications. The properties of these low-dimensional semiconductor systems are directly related to the atomic arrangement, distribution and size of the quantum dots, the structure of the surrounding matrices and the distance between the quantum dots. The quantum confinement of carriers in the quantum dots, their interaction, and local states in the matrices are the dominating factors determining the material properties.The present work focuses on studying the atomic structures of these materials, and how their optical and electronic properties vary as a function of size and structure. Two material systems were especially synthesized as part of this work; Si and Ge quantum dots embedded This PhD project was motivated by the potential of the third generation solar cells, which seek to increase the device efficiency above the Shockley-Queisser limit, and the recent advances in aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy that allow the investigation of the electronic structure and chemistry of materials with sub-angstrom spatial resolution. The work focused on studies of the structure and electronic properties of semiconductor quantum dots using mainly transmission electron microscopy and electron energy-loss spectroscopy. The synthesis and structural characterization of the semiconductor quantum dots were carried out at the Structure Physics group, University of Oslo. Due to the extremely small dimensions of the quantum dots and the need of high spatial and energy resolution instrument for very detail experiments, the investigation of the quantum dots' chemical bonding and electronic properties was carried out by advanced analytical scanning transmission electron microscopy at the SuperSTEM Laboratory. There is a direct continuation of, and an improvement on, the important and novel results reported in the first to the third paper, which provided one of the first direct experimental evidence for the presence of quantum confinement effects in individual Si and Ge quantum dots in a dielectric matrix. The contribution from this work very much provides an improved understanding of the condensed matter physics responsible for the quantum behaviors of the quantum dots, while from a practical point of view it would also arguably provides important result for the photovoltaic community concerned with device/materials performance.vii

show abstract

“…Blue shifts and splittings of the E 1 and E 2 transitions were measured in GaAs/AlAs superlattices 3,4 . More recently, a quantum confinement induced shift of E 1 and E 2 was measured in Ge nanoparticles embedded in a glassy matrix 5,6 . A main purpose of this work is to calculate the behavior of E 1 and E 2 transitions upon confinement in GaAs/AlAs superlattices and in free-standing GaAs layers, which are simulated by GaAs/vacuum superlattices.…”

Section: Introductionmentioning

confidence: 99%

Electronic states and optical properties of GaAs/AlAs and GaAs/vacuum superlattices by the linear combination of bulk bands method

Botti

Andreani²

2001

Phys. Rev. B

Self Cite

View full text Add to dashboard Cite

The linear combination of bulk bands method recently introduced by Wang, Franceschetti and Zunger [Phys. Rev. Lett. 78, 2819 (1997)] is applied to a calculation of energy bands and optical constants of (GaAs)n/(AlAs)n and (GaAs)n/(vacuum)n (001) superlattices with n ranging from 4 to 20. Empirical pseudopotentials are used for the calculation of the bulk energy bands. Quantumconfined induced shifts of critical point energies are calculated and are found to be larger for the GaAs/vacuum system. The E1 peak in the absorption spectra has a blue shift and splits into two peaks for decreasing superlattice period; the E2 transition instead is found to be split for large-period GaAs/AlAs superlattices. The band contribution to linear birefringence of GaAs/AlAs superlattices is calculated and compared with recent experimental results of Sirenko et al. [Phys. Rev. B 60, 8253 (1999)]. The frequency-dependent part reproduces the observed increase with decreasing superlattice period, while the calculated zero-frequency birefringence does not account for the experimental results and points to the importance of local-field effects.

show abstract

Different quantum behavior of theE1andE2spectral structures in

Cited by 69 publications

References 28 publications

Optical Properties of Germanium Nanocrystals

Optical Properties of Germanium Nanocrystals

Direct observation of quantum confinement of Si nanocrystals in Si-rich nitrides

Electronic states and optical properties of GaAs/AlAs and GaAs/vacuum superlattices by the linear combination of bulk bands method

Contact Info

Product

Resources

About