Optical spectroscopy of quasimonolayer InAs at the onset of quantum-dot nucleation

Bhatti, Arshad Saleem; Alessi, M. Grassi; Capizzi, M.; Frigeri, P.; Franchi, Stefano

doi:10.1103/physrevb.60.2592

Cited by 43 publications

(17 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Differently from what we previously observed in monolayer-sized InAs/GaAs single quantum wells [8], in the present case only the heavy-hole free-exciton PR feature could be detected, due to the weakness of the signal. The comparison with recently reported PL results [9,10] concerning the relation between the critical thickness for QD nucleation and the optical response of WLs indicates an effective thickness of 1.6-1.8 ML, in agreement with the critical thickness for the 2D-3D transition of InAs grown on GaAs.…”

Section: Resultssupporting

confidence: 62%

“…As regards QD2, the second and less intense PR feature, due to its energy position (about 100 meV higher than QD1), it should be attributed either to excited state transitions or to the ground state transition of a second QD family [10,13,16], with a different size and/or morphology with respect to the main family. We lean towards the second attribution consistently with the observation of a different N dependence for the QD1 and QD2 transition energies (see below) and with the morphological characterization by AFM and TEM.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Photoreflectance characterization of InAs/GaAs self-assembled quantum dots grown by ALMBE

et al. 2000

Self Cite

View full text Add to dashboard Cite

Abstract. We report on a photoreflectance investigation in the 0.8-1.5 eV photon energy range and at temperatures from 80 to 300 K on stacked layers of InAs/GaAs self-assembled quantum dots (QDs) grown by Atomic-Layer Molecular Beam Epitaxy. We observed clear and well-resolved structures, which we attribute to the optical response of different QD families. The dependence of the ground state transition energy on the number of stacked QD layers is investigated and discussed considering vertical coupling between dots of the same column. It is shown that Coulomb interaction can account for the observed optical response of QD families with different morphology coexisting in the same sample.

show abstract

Section: Resultssupporting

confidence: 62%

Section: Resultsmentioning

confidence: 99%

Photoreflectance characterization of InAs/GaAs self-assembled quantum dots grown by ALMBE

et al. 2000

Self Cite

View full text Add to dashboard Cite

show abstract

“…As a consequence, properties that depend crucially on the strong directional bonding characteristic of semiconductors cannot be addressed by our model. Some examples are: the dependence of the shape of GeSi/Si dots on volume 4,5,6 as discussed above; the observation of lens-shaped 29,30 and pyramidal 31 dots and even of coexistence of both types 32 in InAs/GaAs, the other wellstudied system (for a recent review see Ref. 33) or the cases where the accommodation of the lattice misfit of a given material on different crystallographic faces of the same substrate takes place by other mechanisms (also found for InAs/GaAs), 34 where additional aspects as the presence of different surface reconstructions affect the thermodynamical balance of surface energies as well as the diffusion kinetics and, as a consequence, the nucleation behaviour and the growth mode.…”

Section: Modelmentioning

confidence: 99%

Quantum-dot nucleation in strained-layer epitaxy: Minimum-energy pathway in the stress-driven two-dimensional to three-dimensional transformation

Prieto

Markov

2005

Phys. Rev. B

View full text Add to dashboard Cite

The transformation of monolayer islands into bilayer islands as a first step of the overall twodimensional to three-dimensional (2D-3D) transformation in the coherent Stranski-Krastanov mode of growth is studied for the cases of expanded and compressed overlayers. Compressed overlayers display a nucleation-like behavior: the energy accompanying the transformation process displays a maximum at some critical number of atoms, which is small for large enough values of the misfit, and then decreases gradually down to the completion of the transformation, non-monotonically due to the atomistics of the process. On the contrary, the energy change in expanded overlayers increases up to close to the completion of the transformation and then abruptly collapses with the disappearance of the monoatomic steps to produce low-energy facets. This kind of transformation takes place only in materials with strong interatomic bonding. Softer materials under tensile stress are expected to grow predominantly with a planar morphology until misfit dislocations are introduced, or to transform into 3D islands by a different mechanism. It is concluded that the coherent StranskiKrastanov growth in expanded overlayers is much less probable than in compressed ones for kinetic reasons.

show abstract

“…The best agreement between the experiment and calculation has been obtained for the WL thickness of about 1.6 monolayer and the band offset in the conduction band ͑Q C ͒ of about 87% ͑Q C taken for the unstrained materials, i.e., the so-called chemical band offset which corresponds to about 65% of the band offset in the real strained structure͒, which are reasonable values when compared to those cited in the literature. [17][18][19][26][27][28] In the real case, one would expect some intermixing of the WL QW due to the possible In-Ga atom exchange during growth or some interdiffusion. In general, these processes should modify the confinement potential significantly and also shift the optical transition energies.…”

Section: Resultsmentioning

confidence: 99%

“…[9][10][11][12][13][14][15][16] They are very similar in many reports and are usually in satisfactory agreea͒ Author to whom correspondence should be addressed; electronic mail: grzegorz.sek@pwr.wroc.pl ment with the calculations assuming a rectangular well shape and its fractional thickness of about 1.5 monolayer. [17][18][19] In this paper we aim at presenting a more detailed discussion of the optical transitions related to the existence of the wetting layer in the InAs/ GaAs QD structures, for which we use as main experimental tools the transmission electron microscopy ͑TEM͒ to deduce the composition profiles and photoreflectance spectroscopy to study the absorptionlike spectra. In particular, we would like to address the following issues: ͑i͒ Why do the WL optical transition energies seem to be constant independent of the structure history?…”

Section: Introductionmentioning

confidence: 99%

Wetting layer states of InAs∕GaAs self-assembled quantum dot structures: Effect of intermixing and capping layer

Sęk

Ryczko

Motyka

et al. 2007

Journal of Applied Physics

View full text Add to dashboard Cite

Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publicationCitation for published version (APA): Sek, G., Ryczko, K., Motyka, M., Andrzejewski, J., Wysocka, K., Misiewicz, J., ... Patriarche, G. (2007). Wetting layer states of InAs/GaAs self-assembled quantum dot structures. Effect of intermixing and capping layer. Journal of Applied Physics, 101(6), 063539-1/7. [063539]. DOI: 10.1063/1.2711146 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. The authors present a modulated reflectivity study of the wetting layer ͑WL͒ states in molecular beam epitaxy grown InAs/ GaAs quantum dot ͑QD͒ structures designed to emit light in the 1.3-1.5 m range. A high sensitivity of the technique has allowed the observation of all optical transitions in the QD system, including low oscillator strength transitions related to QD ground and excited states, and the ones connected with the WL quantum well ͑QW͒. The support of WL content profiles, determined by transmission electron microscopy, has made it possible to analyze in detail the real WL QW confinement potential which was then used for calculating the optical transition energies. We could conclude that in spite of a very effective WL QW intermixing, mainly due to the Ga-In exchange process ͑causing the reduction of the maximum indium content in the WL layer to about 35% from nominally deposited InAs͒, the transition energies remain almost unaffected. The latter effect could be explained in effective mass envelope function calculations taking into account the intermixing of the QW interfaces described within the diffusion model. We have followed the WL-...

show abstract

Optical spectroscopy of quasimonolayer InAs at the onset of quantum-dot nucleation

Cited by 43 publications

References 22 publications

Photoreflectance characterization of InAs/GaAs self-assembled quantum dots grown by ALMBE

Photoreflectance characterization of InAs/GaAs self-assembled quantum dots grown by ALMBE

Quantum-dot nucleation in strained-layer epitaxy: Minimum-energy pathway in the stress-driven two-dimensional to three-dimensional transformation

Wetting layer states of InAs∕GaAs self-assembled quantum dot structures: Effect of intermixing and capping layer

Contact Info

Product

Resources

About